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| [ | |
| { | |
| "id": "gt-auc-vickrey-0012", | |
| "category": "auction_theory", | |
| "subcategory": "vickrey_second_price", | |
| "difficulty": "easy", | |
| "problem": "In the following Vickrey auction, 3 bidders compete for a single item:\n\nEach bidder has a private valuation for the item:\n- Bidder 1: values the item at $18\n- Bidder 2: values the item at $112\n- Bidder 3: values the item at $90\n\nThe highest bidder wins and pays the second-highest bid.\n\nDetermine the dominant strategy equilibrium, the winner, and the payment.", | |
| "solution": "**Dominant Strategy Analysis:**\n\nIn a second-price (Vickrey) auction, each bidder's dominant strategy is to bid their true valuation.\nThis is because:\n- Bidding above your value risks winning at a price above your value (negative surplus).\n- Bidding below your value risks losing when you could have won profitably.\n- Bidding your true value is weakly dominant regardless of others' bids. \u2713\n\n**Equilibrium Bids:**\n- Bidder 1 bids $18 (= true valuation)\n- Bidder 2 bids $112 (= true valuation)\n- Bidder 3 bids $90 (= true valuation)\n\n**Auction Outcome:**\n- Winner: Bidder 2 (highest bid: $112)\n- Payment: $90 (second-highest bid)\n- Winner's surplus: $112 - $90 = $22\n- All other bidders pay nothing and get nothing.", | |
| "answer": "Dominant strategy: bid true value. Winner: Bidder 2 ($112), Price: $90, Surplus: $22", | |
| "game_type": "sequential", | |
| "players": 3, | |
| "tags": [ | |
| "auction", | |
| "vickrey", | |
| "second_price", | |
| "dominant_strategy", | |
| "private_value", | |
| "3_bidders" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-vickrey-0001", | |
| "category": "auction_theory", | |
| "subcategory": "vickrey_second_price", | |
| "difficulty": "easy", | |
| "problem": "3 bidders participate in a sealed-bid second-price auction:\n\nEach bidder has a private valuation for the item:\n- Bidder 1: values the item at $45\n- Bidder 2: values the item at $198\n- Bidder 3: values the item at $36\n\nThe highest bidder wins and pays the second-highest bid.\n\nWhat is the equilibrium bidding strategy? Determine the winner and price paid.", | |
| "solution": "**Dominant Strategy Analysis:**\n\nIn a second-price (Vickrey) auction, each bidder's dominant strategy is to bid their true valuation.\nThis is because:\n- Bidding above your value risks winning at a price above your value (negative surplus).\n- Bidding below your value risks losing when you could have won profitably.\n- Bidding your true value is weakly dominant regardless of others' bids. \u2713\n\n**Equilibrium Bids:**\n- Bidder 1 bids $45 (= true valuation)\n- Bidder 2 bids $198 (= true valuation)\n- Bidder 3 bids $36 (= true valuation)\n\n**Auction Outcome:**\n- Winner: Bidder 2 (highest bid: $198)\n- Payment: $45 (second-highest bid)\n- Winner's surplus: $198 - $45 = $153\n- All other bidders pay nothing and get nothing.", | |
| "answer": "Dominant strategy: bid true value. Winner: Bidder 2 ($198), Price: $45, Surplus: $153", | |
| "game_type": "sequential", | |
| "players": 3, | |
| "tags": [ | |
| "auction", | |
| "vickrey", | |
| "second_price", | |
| "dominant_strategy", | |
| "private_value", | |
| "3_bidders" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-vickrey-0033", | |
| "category": "auction_theory", | |
| "subcategory": "vickrey_second_price", | |
| "difficulty": "easy", | |
| "problem": "In the following Vickrey auction, 2 bidders compete for a single item:\n\nEach bidder has a private valuation for the item:\n- Bidder 1: values the item at $159\n- Bidder 2: values the item at $22\n\nThe highest bidder wins and pays the second-highest bid.\n\nDetermine the dominant strategy equilibrium, the winner, and the payment.", | |
| "solution": "**Dominant Strategy Analysis:**\n\nIn a second-price (Vickrey) auction, each bidder's dominant strategy is to bid their true valuation.\nThis is because:\n- Bidding above your value risks winning at a price above your value (negative surplus).\n- Bidding below your value risks losing when you could have won profitably.\n- Bidding your true value is weakly dominant regardless of others' bids. \u2713\n\n**Equilibrium Bids:**\n- Bidder 1 bids $159 (= true valuation)\n- Bidder 2 bids $22 (= true valuation)\n\n**Auction Outcome:**\n- Winner: Bidder 1 (highest bid: $159)\n- Payment: $22 (second-highest bid)\n- Winner's surplus: $159 - $22 = $137\n- All other bidders pay nothing and get nothing.", | |
| "answer": "Dominant strategy: bid true value. Winner: Bidder 1 ($159), Price: $22, Surplus: $137", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "auction", | |
| "vickrey", | |
| "second_price", | |
| "dominant_strategy", | |
| "private_value", | |
| "2_bidders" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-fp-0049", | |
| "category": "auction_theory", | |
| "subcategory": "first_price_sealed", | |
| "difficulty": "medium", | |
| "problem": "In this first-price auction, 3 bidders have private valuations drawn from Uniform[0, 100]:\n\n3 bidders, each with a private valuation drawn independently from Uniform[0, 100].\nHighest bidder wins and pays their own bid.\nAll bidders are risk-neutral and rational.\n\nDetermine the equilibrium bid function and expected revenue.", | |
| "solution": "**Equilibrium Bidding Strategy:**\n\nWith 3 bidders and values drawn from Uniform[0, 100], the symmetric Bayesian Nash Equilibrium bid function is:\n\n b(v) = ((n-1)/n) \u00d7 v = (2/3) \u00d7 v\n\n**Derivation:**\n- Each bidder shades their bid below their true value.\n- The optimal shade balances: higher bid = more likely to win, but less surplus if you win.\n- With Uniform[0,100] values, probability of winning with bid b when others bid (2/3)v:\n P(win) = (b \u00d7 3/2)^2 / 100^2\n- Maximizing expected payoff (v - b) \u00d7 P(win) yields b*(v) = (2/3)v. \u2713\n\n**Expected Revenue:**\n- E[Revenue] = (n-1)/(n+1) \u00d7 V_max = (2/4) \u00d7 100 = 50.00\n\n**Comparison to Vickrey:**\n- By Revenue Equivalence Theorem, this equals the expected revenue from a second-price auction. \u2713", | |
| "answer": "BNE: b(v)=(2/3)v, E[Revenue]=50.00", | |
| "game_type": "simultaneous", | |
| "players": 3, | |
| "tags": [ | |
| "auction", | |
| "first_price", | |
| "sealed_bid", | |
| "bayesian_nash", | |
| "private_value", | |
| "3_bidders", | |
| "bid_shading" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-fp-0034", | |
| "category": "auction_theory", | |
| "subcategory": "first_price_sealed", | |
| "difficulty": "medium", | |
| "problem": "Consider a first-price sealed-bid auction with 2 bidders whose values are independently drawn from Uniform[0, 200]:\n\n2 bidders, each with a private valuation drawn independently from Uniform[0, 200].\nHighest bidder wins and pays their own bid.\nAll bidders are risk-neutral and rational.\n\nFind the symmetric Bayesian Nash Equilibrium bidding strategy.", | |
| "solution": "**Equilibrium Bidding Strategy:**\n\nWith 2 bidders and values drawn from Uniform[0, 200], the symmetric Bayesian Nash Equilibrium bid function is:\n\n b(v) = ((n-1)/n) \u00d7 v = (1/2) \u00d7 v\n\n**Derivation:**\n- Each bidder shades their bid below their true value.\n- The optimal shade balances: higher bid = more likely to win, but less surplus if you win.\n- With Uniform[0,200] values, probability of winning with bid b when others bid (1/2)v:\n P(win) = (b \u00d7 2/1)^1 / 200^1\n- Maximizing expected payoff (v - b) \u00d7 P(win) yields b*(v) = (1/2)v. \u2713\n\n**Expected Revenue:**\n- E[Revenue] = (n-1)/(n+1) \u00d7 V_max = (1/3) \u00d7 200 = 66.67\n\n**Comparison to Vickrey:**\n- By Revenue Equivalence Theorem, this equals the expected revenue from a second-price auction. \u2713", | |
| "answer": "BNE: b(v)=(1/2)v, E[Revenue]=66.67", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "auction", | |
| "first_price", | |
| "sealed_bid", | |
| "bayesian_nash", | |
| "private_value", | |
| "2_bidders", | |
| "bid_shading" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-vickrey-0068", | |
| "category": "auction_theory", | |
| "subcategory": "vickrey_second_price", | |
| "difficulty": "medium", | |
| "problem": "Analyze this second-price auction:\n\nEach bidder has a private valuation for the item:\n- Bidder 1: values the item at $116\n- Bidder 2: values the item at $25\n- Bidder 3: values the item at $117\n- Bidder 4: values the item at $109\n- Bidder 5: values the item at $129\n- Bidder 6: values the item at $62\n\nThe highest bidder wins and pays the second-highest bid.\n\nFind each bidder's optimal bidding strategy and the auction outcome.", | |
| "solution": "**Dominant Strategy Analysis:**\n\nIn a second-price (Vickrey) auction, each bidder's dominant strategy is to bid their true valuation.\nThis is because:\n- Bidding above your value risks winning at a price above your value (negative surplus).\n- Bidding below your value risks losing when you could have won profitably.\n- Bidding your true value is weakly dominant regardless of others' bids. \u2713\n\n**Equilibrium Bids:**\n- Bidder 1 bids $116 (= true valuation)\n- Bidder 2 bids $25 (= true valuation)\n- Bidder 3 bids $117 (= true valuation)\n- Bidder 4 bids $109 (= true valuation)\n- Bidder 5 bids $129 (= true valuation)\n- Bidder 6 bids $62 (= true valuation)\n\n**Auction Outcome:**\n- Winner: Bidder 5 (highest bid: $129)\n- Payment: $117 (second-highest bid)\n- Winner's surplus: $129 - $117 = $12\n- All other bidders pay nothing and get nothing.", | |
| "answer": "Dominant strategy: bid true value. Winner: Bidder 5 ($129), Price: $117, Surplus: $12", | |
| "game_type": "sequential", | |
| "players": 6, | |
| "tags": [ | |
| "auction", | |
| "vickrey", | |
| "second_price", | |
| "dominant_strategy", | |
| "private_value", | |
| "6_bidders" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-fp-0043", | |
| "category": "auction_theory", | |
| "subcategory": "first_price_sealed", | |
| "difficulty": "hard", | |
| "problem": "In this first-price auction, 10 bidders have private valuations drawn from Uniform[0, 100]:\n\n10 bidders, each with a private valuation drawn independently from Uniform[0, 100].\nHighest bidder wins and pays their own bid.\nAll bidders are risk-neutral and rational.\n\nDetermine the equilibrium bid function and expected revenue.", | |
| "solution": "**Equilibrium Bidding Strategy:**\n\nWith 10 bidders and values drawn from Uniform[0, 100], the symmetric Bayesian Nash Equilibrium bid function is:\n\n b(v) = ((n-1)/n) \u00d7 v = (9/10) \u00d7 v\n\n**Derivation:**\n- Each bidder shades their bid below their true value.\n- The optimal shade balances: higher bid = more likely to win, but less surplus if you win.\n- With Uniform[0,100] values, probability of winning with bid b when others bid (9/10)v:\n P(win) = (b \u00d7 10/9)^9 / 100^9\n- Maximizing expected payoff (v - b) \u00d7 P(win) yields b*(v) = (9/10)v. \u2713\n\n**Expected Revenue:**\n- E[Revenue] = (n-1)/(n+1) \u00d7 V_max = (9/11) \u00d7 100 = 81.82\n\n**Comparison to Vickrey:**\n- By Revenue Equivalence Theorem, this equals the expected revenue from a second-price auction. \u2713", | |
| "answer": "BNE: b(v)=(9/10)v, E[Revenue]=81.82", | |
| "game_type": "simultaneous", | |
| "players": 10, | |
| "tags": [ | |
| "auction", | |
| "first_price", | |
| "sealed_bid", | |
| "bayesian_nash", | |
| "private_value", | |
| "10_bidders", | |
| "bid_shading" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-fp-0036", | |
| "category": "auction_theory", | |
| "subcategory": "first_price_sealed", | |
| "difficulty": "hard", | |
| "problem": "Analyze the following first-price sealed-bid auction:\n\n5 bidders, each with a private valuation drawn independently from Uniform[0, 200].\nHighest bidder wins and pays their own bid.\nAll bidders are risk-neutral and rational.\n\nSuppose the realized valuations are:\n- Bidder 1: v = 154\n- Bidder 2: v = 131\n- Bidder 3: v = 99\n- Bidder 4: v = 49\n- Bidder 5: v = 38\n\nWhat is the equilibrium bidding strategy? Compare it to truthful bidding.", | |
| "solution": "**Equilibrium Bidding Strategy:**\n\nWith 5 bidders and values drawn from Uniform[0, 200], the symmetric Bayesian Nash Equilibrium bid function is:\n\n b(v) = ((n-1)/n) \u00d7 v = (4/5) \u00d7 v\n\n**Derivation:**\n- Each bidder shades their bid below their true value.\n- The optimal shade balances: higher bid = more likely to win, but less surplus if you win.\n- With Uniform[0,200] values, probability of winning with bid b when others bid (4/5)v:\n P(win) = (b \u00d7 5/4)^4 / 200^4\n- Maximizing expected payoff (v - b) \u00d7 P(win) yields b*(v) = (4/5)v. \u2713\n\n**Example with given valuations:**\n- Bidder 1: v=154, bids (4/5)\u00d7154 = 123.2\n- Bidder 2: v=131, bids (4/5)\u00d7131 = 104.8\n- Bidder 3: v=99, bids (4/5)\u00d799 = 79.2\n- Bidder 4: v=49, bids (4/5)\u00d749 = 39.2\n- Bidder 5: v=38, bids (4/5)\u00d738 = 30.4\n- Winner: Bidder 1 (highest bid: 123.2)\n- Payment: 123.2\n\n**Expected Revenue:**\n- E[Revenue] = (n-1)/(n+1) \u00d7 V_max = (4/6) \u00d7 200 = 133.33\n\n**Comparison to Vickrey:**\n- By Revenue Equivalence Theorem, this equals the expected revenue from a second-price auction. \u2713", | |
| "answer": "BNE: b(v)=(4/5)v, E[Revenue]=133.33", | |
| "game_type": "simultaneous", | |
| "players": 5, | |
| "tags": [ | |
| "auction", | |
| "first_price", | |
| "sealed_bid", | |
| "bayesian_nash", | |
| "private_value", | |
| "5_bidders", | |
| "bid_shading" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-curse-0017", | |
| "category": "auction_theory", | |
| "subcategory": "winners_curse", | |
| "difficulty": "hard", | |
| "problem": "In this common-value auction, bidders receive noisy signals:\n\nAn item has an unknown common value V for all bidders.\nEach of 2 bidders receives a private signal: si = V + \u03b5i, where \u03b5i ~ Uniform[-10, +10].\nThe auction is a first-price sealed-bid.\n\nAnalyze the winner's curse and find the optimal shading strategy.", | |
| "solution": "**Winner's Curse Analysis:**\n\nThe winner's curse arises because winning a common-value auction means you likely had\nthe most optimistic signal. If you bid naively based on your signal, you systematically overpay.\n\n**Key Insight:**\n- Your signal si is an unbiased estimate of V.\n- But conditional on WINNING (having the highest signal), your signal is biased upward.\n- Expected bias of the highest of 2 signals from Uniform[-10, +10]:\n E[max(\u03b51,...,\u03b52)] = 10 \u00d7 (2-1)/(2+1) = 10\u00d71/3 = 3.33\n- Therefore, conditional on winning: E[V | win] \u2248 si - 3.33\n\n**Optimal Bidding Strategy:**\n- Shade bid: b(si) = si - 3.33\n- This corrects for the selection bias of winning. \u2713\n", | |
| "answer": "Shade amount: 3.33, Optimal bid: b(s) = s - 3.33", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "auction", | |
| "winners_curse", | |
| "common_value", | |
| "bid_shading", | |
| "2_bidders", | |
| "information_asymmetry" | |
| ] | |
| }, | |
| { | |
| "id": "gt-auc-vickrey-0018", | |
| "category": "auction_theory", | |
| "subcategory": "vickrey_second_price", | |
| "difficulty": "medium", | |
| "problem": "Consider a second-price sealed-bid (Vickrey) auction with 5 bidders:\n\nEach bidder has a private valuation for the item:\n- Bidder 1: values the item at $38\n- Bidder 2: values the item at $14\n- Bidder 3: values the item at $71\n- Bidder 4: values the item at $88\n- Bidder 5: values the item at $102\n\nThe highest bidder wins and pays the second-highest bid.\n\nWhat is each bidder's dominant strategy? Who wins and what price do they pay?", | |
| "solution": "**Dominant Strategy Analysis:**\n\nIn a second-price (Vickrey) auction, each bidder's dominant strategy is to bid their true valuation.\nThis is because:\n- Bidding above your value risks winning at a price above your value (negative surplus).\n- Bidding below your value risks losing when you could have won profitably.\n- Bidding your true value is weakly dominant regardless of others' bids. \u2713\n\n**Equilibrium Bids:**\n- Bidder 1 bids $38 (= true valuation)\n- Bidder 2 bids $14 (= true valuation)\n- Bidder 3 bids $71 (= true valuation)\n- Bidder 4 bids $88 (= true valuation)\n- Bidder 5 bids $102 (= true valuation)\n\n**Auction Outcome:**\n- Winner: Bidder 5 (highest bid: $102)\n- Payment: $88 (second-highest bid)\n- Winner's surplus: $102 - $88 = $14\n- All other bidders pay nothing and get nothing.", | |
| "answer": "Dominant strategy: bid true value. Winner: Bidder 5 ($102), Price: $88, Surplus: $14", | |
| "game_type": "sequential", | |
| "players": 5, | |
| "tags": [ | |
| "auction", | |
| "vickrey", | |
| "second_price", | |
| "dominant_strategy", | |
| "private_value", | |
| "5_bidders" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-2type-0017", | |
| "category": "bayesian_game", | |
| "subcategory": "two_type_bayesian", | |
| "difficulty": "hard", | |
| "problem": "Analyze this Bayesian game where players have private information:\n\nPlayer 1 has a private type: Strong (probability 8/10) or Weak (probability 2/10).\nPlayer 2 does not know Player 1's type.\nBoth players choose from: {Enter, Stay Out}.\n\nPayoffs (Player 1, Player 2) if Player 1 is type Strong:\nP1 \\ P2 | Enter | Stay Out\n--- | --- | ---\nEnter | (6,4) | (2,2)\nStay Out | (-5,1) | (7,5)\n\nPayoffs if Player 1 is type Weak:\nP1 \\ P2 | Enter | Stay Out\n--- | --- | ---\nEnter | (3,-3) | (3,6)\nStay Out | (7,5) | (-5,-2)\n\nWhat is the Bayesian Nash Equilibrium?", | |
| "solution": "**Bayesian Nash Equilibrium Analysis:**\n\nPrior: P(Strong) = 8/10, P(Weak) = 2/10\n\n**BNE 1:**\n- Player 1 (Strong type): plays Enter\n Check: payoff from Enter = 6 vs alternative = -5. \u2713\n- Player 1 (Weak type): plays Stay Out\n Check: payoff from Stay Out = 7 vs alternative = 3. \u2713\n- Player 2: plays Enter\n Expected payoff: 8/10\u00d74 + 2/10\u00d75 = 4.2\n vs alternative Stay Out: 1.2. \u2713\n\n**BNE 2:**\n- Player 1 (Strong type): plays Stay Out\n Check: payoff from Stay Out = 7 vs alternative = 2. \u2713\n- Player 1 (Weak type): plays Enter\n Check: payoff from Enter = 3 vs alternative = -5. \u2713\n- Player 2: plays Stay Out\n Expected payoff: 8/10\u00d75 + 2/10\u00d76 = 5.2\n vs alternative Enter: 0.2. \u2713\n", | |
| "answer": "BNE1: P1(Strong)=Enter, P1(Weak)=Stay Out, P2=Enter; BNE2: P1(Strong)=Stay Out, P1(Weak)=Enter, P2=Stay Out", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "incomplete_information", | |
| "bayesian_nash", | |
| "private_type", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-2type-0057", | |
| "category": "bayesian_game", | |
| "subcategory": "two_type_bayesian", | |
| "difficulty": "hard", | |
| "problem": "Players have private types in the following game:\n\nPlayer 1 has a private type: High (probability 5/10) or Low (probability 5/10).\nPlayer 2 does not know Player 1's type.\nBoth players choose from: {High Price, Low Price}.\n\nPayoffs (Player 1, Player 2) if Player 1 is type High:\nP1 \\ P2 | High Price | Low Price\n--- | --- | ---\nHigh Price | (-5,0) | (3,4)\nLow Price | (5,6) | (-5,0)\n\nPayoffs if Player 1 is type Low:\nP1 \\ P2 | High Price | Low Price\n--- | --- | ---\nHigh Price | (-1,7) | (-3,-1)\nLow Price | (-5,-3) | (1,7)\n\nSolve for the Bayesian Nash Equilibrium strategies.", | |
| "solution": "**Bayesian Nash Equilibrium Analysis:**\n\nPrior: P(High) = 5/10, P(Low) = 5/10\n\n**BNE 1:**\n- Player 1 (High type): plays High Price\n Check: payoff from High Price = 3 vs alternative = -5. \u2713\n- Player 1 (Low type): plays Low Price\n Check: payoff from Low Price = 1 vs alternative = -3. \u2713\n- Player 2: plays Low Price\n Expected payoff: 5/10\u00d74 + 5/10\u00d77 = 5.5\n vs alternative High Price: -1.5. \u2713\n\n**BNE 2:**\n- Player 1 (High type): plays Low Price\n Check: payoff from Low Price = 5 vs alternative = -5. \u2713\n- Player 1 (Low type): plays High Price\n Check: payoff from High Price = -1 vs alternative = -5. \u2713\n- Player 2: plays High Price\n Expected payoff: 5/10\u00d76 + 5/10\u00d77 = 6.5\n vs alternative Low Price: -0.5. \u2713\n", | |
| "answer": "BNE1: P1(High)=High Price, P1(Low)=Low Price, P2=Low Price; BNE2: P1(High)=Low Price, P1(Low)=High Price, P2=High Price", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "incomplete_information", | |
| "bayesian_nash", | |
| "private_type", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-2type-0133", | |
| "category": "bayesian_game", | |
| "subcategory": "two_type_bayesian", | |
| "difficulty": "hard", | |
| "problem": "Consider the following Bayesian game with incomplete information:\n\nPlayer 1 has a private type: Cooperative (probability 4/10) or Aggressive (probability 6/10).\nPlayer 2 does not know Player 1's type.\nBoth players choose from: {Invest, Wait}.\n\nPayoffs (Player 1, Player 2) if Player 1 is type Cooperative:\nP1 \\ P2 | Invest | Wait\n--- | --- | ---\nInvest | (10,7) | (-2,2)\nWait | (10,-3) | (-5,6)\n\nPayoffs if Player 1 is type Aggressive:\nP1 \\ P2 | Invest | Wait\n--- | --- | ---\nInvest | (5,-1) | (7,8)\nWait | (6,0) | (10,-3)\n\nFind the Bayesian Nash Equilibrium.", | |
| "solution": "**Bayesian Nash Equilibrium Analysis:**\n\nPrior: P(Cooperative) = 4/10, P(Aggressive) = 6/10\n\n**BNE 1:**\n- Player 1 (Cooperative type): plays Invest\n Check: payoff from Invest = 10 vs alternative = 10. \u2713\n- Player 1 (Aggressive type): plays Wait\n Check: payoff from Wait = 6 vs alternative = 5. \u2713\n- Player 2: plays Invest\n Expected payoff: 4/10\u00d77 + 6/10\u00d70 = 2.8\n vs alternative Wait: -1.0. \u2713\n", | |
| "answer": "BNE1: P1(Cooperative)=Invest, P1(Aggressive)=Wait, P2=Invest", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "incomplete_information", | |
| "bayesian_nash", | |
| "private_type", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-2type-0146", | |
| "category": "bayesian_game", | |
| "subcategory": "two_type_bayesian", | |
| "difficulty": "hard", | |
| "problem": "Analyze this Bayesian game where players have private information:\n\nPlayer 1 has a private type: Strong (probability 8/10) or Weak (probability 2/10).\nPlayer 2 does not know Player 1's type.\nBoth players choose from: {Cooperate, Defect}.\n\nPayoffs (Player 1, Player 2) if Player 1 is type Strong:\nP1 \\ P2 | Cooperate | Defect\n--- | --- | ---\nCooperate | (8,10) | (-4,-3)\nDefect | (3,7) | (-1,8)\n\nPayoffs if Player 1 is type Weak:\nP1 \\ P2 | Cooperate | Defect\n--- | --- | ---\nCooperate | (1,2) | (-5,7)\nDefect | (6,10) | (10,6)\n\nWhat is the Bayesian Nash Equilibrium?", | |
| "solution": "**Bayesian Nash Equilibrium Analysis:**\n\nPrior: P(Strong) = 8/10, P(Weak) = 2/10\n\n**BNE 1:**\n- Player 1 (Strong type): plays Cooperate\n Check: payoff from Cooperate = 8 vs alternative = 3. \u2713\n- Player 1 (Weak type): plays Defect\n Check: payoff from Defect = 6 vs alternative = 1. \u2713\n- Player 2: plays Cooperate\n Expected payoff: 8/10\u00d710 + 2/10\u00d710 = 10.0\n vs alternative Defect: -1.2. \u2713\n\n**BNE 2:**\n- Player 1 (Strong type): plays Defect\n Check: payoff from Defect = -1 vs alternative = -4. \u2713\n- Player 1 (Weak type): plays Defect\n Check: payoff from Defect = 10 vs alternative = -5. \u2713\n- Player 2: plays Defect\n Expected payoff: 8/10\u00d78 + 2/10\u00d76 = 7.6\n vs alternative Cooperate: 7.6. \u2713\n", | |
| "answer": "BNE1: P1(Strong)=Cooperate, P1(Weak)=Defect, P2=Cooperate; BNE2: P1(Strong)=Defect, P1(Weak)=Defect, P2=Defect", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "incomplete_information", | |
| "bayesian_nash", | |
| "private_type", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-signal-0094", | |
| "category": "bayesian_game", | |
| "subcategory": "signaling_game", | |
| "difficulty": "hard", | |
| "problem": "Consider a signaling game:\n\nA Sender (worker) has private type: High ability (probability 0.4) or Low ability (probability 0.6).\nThe Sender can choose to Signal (e.g., get education) or Not Signal.\nThe Receiver (employer) observes the signal and offers a wage.\n\nParameters:\n- Cost of signaling for High type: 2\n- Cost of signaling for Low type: 7\n- Wage if Receiver believes High: 11\n- Wage if Receiver believes Low: 2\n- Sender payoff = wage - signal cost (if signaled), or wage (if not)\n\nFind the Perfect Bayesian Equilibrium. Is there a separating or pooling equilibrium?", | |
| "solution": "**Signaling Game Analysis:**\n\n**Separating Equilibrium** (High signals, Low doesn't):\n- High type: Signal \u2192 gets wage 11, net payoff = 11 - 2 = 9\n vs Not Signal \u2192 gets wage 2, net payoff = 2\n Prefer Signal? 9 > 2? Yes \u2713\n- Low type: Not Signal \u2192 gets wage 2, net payoff = 2\n vs Signal \u2192 gets wage 11, net payoff = 11 - 7 = 4\n Prefer Not Signal? 2 > 4? No \u2717\n- Separating equilibrium DOES NOT EXIST \u2717\n\n**Pooling Equilibrium** (Both signal or both don't):\n- If both signal: Receiver can't distinguish, offers pooling wage = 0.4\u00d711 + 0.6\u00d72 = 5.6\n High type net: 5.6 - 2 = 3.6\n Low type net: 5.6 - 7 = -1.4\n\n**Result:** No pure strategy PBE found with these parameters", | |
| "answer": "Equilibria: No pure strategy PBE found with these parameters", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "signaling", | |
| "incomplete_information", | |
| "perfect_bayesian", | |
| "separating", | |
| "pooling", | |
| "private_type" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-2type-0015", | |
| "category": "bayesian_game", | |
| "subcategory": "two_type_bayesian", | |
| "difficulty": "hard", | |
| "problem": "In this game of incomplete information:\n\nPlayer 1 has a private type: Strong (probability 3/10) or Weak (probability 7/10).\nPlayer 2 does not know Player 1's type.\nBoth players choose from: {Cooperate, Defect}.\n\nPayoffs (Player 1, Player 2) if Player 1 is type Strong:\nP1 \\ P2 | Cooperate | Defect\n--- | --- | ---\nCooperate | (9,8) | (-5,-2)\nDefect | (-3,-1) | (-4,6)\n\nPayoffs if Player 1 is type Weak:\nP1 \\ P2 | Cooperate | Defect\n--- | --- | ---\nCooperate | (-1,8) | (-1,-4)\nDefect | (4,6) | (-4,6)\n\nDetermine each type's optimal strategy in the Bayesian Nash Equilibrium.", | |
| "solution": "**Bayesian Nash Equilibrium Analysis:**\n\nPrior: P(Strong) = 3/10, P(Weak) = 7/10\n\n**BNE 1:**\n- Player 1 (Strong type): plays Cooperate\n Check: payoff from Cooperate = 9 vs alternative = -3. \u2713\n- Player 1 (Weak type): plays Defect\n Check: payoff from Defect = 4 vs alternative = -1. \u2713\n- Player 2: plays Cooperate\n Expected payoff: 3/10\u00d78 + 7/10\u00d76 = 6.6\n vs alternative Defect: 3.6. \u2713\n", | |
| "answer": "BNE1: P1(Strong)=Cooperate, P1(Weak)=Defect, P2=Cooperate", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "incomplete_information", | |
| "bayesian_nash", | |
| "private_type", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-2type-0124", | |
| "category": "bayesian_game", | |
| "subcategory": "two_type_bayesian", | |
| "difficulty": "hard", | |
| "problem": "Analyze this Bayesian game where players have private information:\n\nPlayer 1 has a private type: Informed (probability 8/10) or Uninformed (probability 2/10).\nPlayer 2 does not know Player 1's type.\nBoth players choose from: {Fight, Yield}.\n\nPayoffs (Player 1, Player 2) if Player 1 is type Informed:\nP1 \\ P2 | Fight | Yield\n--- | --- | ---\nFight | (10,0) | (-3,-5)\nYield | (2,4) | (-4,3)\n\nPayoffs if Player 1 is type Uninformed:\nP1 \\ P2 | Fight | Yield\n--- | --- | ---\nFight | (2,4) | (0,9)\nYield | (10,-2) | (-2,3)\n\nWhat is the Bayesian Nash Equilibrium?", | |
| "solution": "**Bayesian Nash Equilibrium Analysis:**\n\nPrior: P(Informed) = 8/10, P(Uninformed) = 2/10\n\n**BNE 1:**\n- Player 1 (Informed type): plays Fight\n Check: payoff from Fight = 10 vs alternative = 2. \u2713\n- Player 1 (Uninformed type): plays Yield\n Check: payoff from Yield = 10 vs alternative = 2. \u2713\n- Player 2: plays Fight\n Expected payoff: 8/10\u00d70 + 2/10\u00d7-2 = -0.4\n vs alternative Yield: -3.4. \u2713\n", | |
| "answer": "BNE1: P1(Informed)=Fight, P1(Uninformed)=Yield, P2=Fight", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "incomplete_information", | |
| "bayesian_nash", | |
| "private_type", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-signal-0050", | |
| "category": "bayesian_game", | |
| "subcategory": "signaling_game", | |
| "difficulty": "hard", | |
| "problem": "In this signaling game with two types:\n\nA Sender (worker) has private type: High ability (probability 0.4) or Low ability (probability 0.6).\nThe Sender can choose to Signal (e.g., get education) or Not Signal.\nThe Receiver (employer) observes the signal and offers a wage.\n\nParameters:\n- Cost of signaling for High type: 3\n- Cost of signaling for Low type: 6\n- Wage if Receiver believes High: 11\n- Wage if Receiver believes Low: 4\n- Sender payoff = wage - signal cost (if signaled), or wage (if not)\n\nDetermine whether a separating equilibrium, pooling equilibrium, or both exist.", | |
| "solution": "**Signaling Game Analysis:**\n\n**Separating Equilibrium** (High signals, Low doesn't):\n- High type: Signal \u2192 gets wage 11, net payoff = 11 - 3 = 8\n vs Not Signal \u2192 gets wage 4, net payoff = 4\n Prefer Signal? 8 > 4? Yes \u2713\n- Low type: Not Signal \u2192 gets wage 4, net payoff = 4\n vs Signal \u2192 gets wage 11, net payoff = 11 - 6 = 5\n Prefer Not Signal? 4 > 5? No \u2717\n- Separating equilibrium DOES NOT EXIST \u2717\n\n**Pooling Equilibrium** (Both signal or both don't):\n- If both signal: Receiver can't distinguish, offers pooling wage = 0.4\u00d711 + 0.6\u00d74 = 6.8\n High type net: 6.8 - 3 = 3.8\n Low type net: 6.8 - 6 = 0.8\n\n**Result:** No pure strategy PBE found with these parameters", | |
| "answer": "Equilibria: No pure strategy PBE found with these parameters", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "signaling", | |
| "incomplete_information", | |
| "perfect_bayesian", | |
| "separating", | |
| "pooling", | |
| "private_type" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-2type-0138", | |
| "category": "bayesian_game", | |
| "subcategory": "two_type_bayesian", | |
| "difficulty": "hard", | |
| "problem": "Analyze this Bayesian game where players have private information:\n\nPlayer 1 has a private type: Informed (probability 6/10) or Uninformed (probability 4/10).\nPlayer 2 does not know Player 1's type.\nBoth players choose from: {Enter, Stay Out}.\n\nPayoffs (Player 1, Player 2) if Player 1 is type Informed:\nP1 \\ P2 | Enter | Stay Out\n--- | --- | ---\nEnter | (2,8) | (5,3)\nStay Out | (-3,6) | (-2,-4)\n\nPayoffs if Player 1 is type Uninformed:\nP1 \\ P2 | Enter | Stay Out\n--- | --- | ---\nEnter | (0,2) | (-4,7)\nStay Out | (-3,9) | (4,4)\n\nWhat is the Bayesian Nash Equilibrium?", | |
| "solution": "**Bayesian Nash Equilibrium Analysis:**\n\nPrior: P(Informed) = 6/10, P(Uninformed) = 4/10\n\n**BNE 1:**\n- Player 1 (Informed type): plays Enter\n Check: payoff from Enter = 2 vs alternative = -3. \u2713\n- Player 1 (Uninformed type): plays Enter\n Check: payoff from Enter = 0 vs alternative = -3. \u2713\n- Player 2: plays Enter\n Expected payoff: 6/10\u00d78 + 4/10\u00d72 = 5.6\n vs alternative Stay Out: 4.6. \u2713\n", | |
| "answer": "BNE1: P1(Informed)=Enter, P1(Uninformed)=Enter, P2=Enter", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "incomplete_information", | |
| "bayesian_nash", | |
| "private_type", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-bayes-signal-0065", | |
| "category": "bayesian_game", | |
| "subcategory": "signaling_game", | |
| "difficulty": "hard", | |
| "problem": "In this signaling game with two types:\n\nA Sender (worker) has private type: High ability (probability 0.4) or Low ability (probability 0.6).\nThe Sender can choose to Signal (e.g., get education) or Not Signal.\nThe Receiver (employer) observes the signal and offers a wage.\n\nParameters:\n- Cost of signaling for High type: 2\n- Cost of signaling for Low type: 5\n- Wage if Receiver believes High: 13\n- Wage if Receiver believes Low: 4\n- Sender payoff = wage - signal cost (if signaled), or wage (if not)\n\nDetermine whether a separating equilibrium, pooling equilibrium, or both exist.", | |
| "solution": "**Signaling Game Analysis:**\n\n**Separating Equilibrium** (High signals, Low doesn't):\n- High type: Signal \u2192 gets wage 13, net payoff = 13 - 2 = 11\n vs Not Signal \u2192 gets wage 4, net payoff = 4\n Prefer Signal? 11 > 4? Yes \u2713\n- Low type: Not Signal \u2192 gets wage 4, net payoff = 4\n vs Signal \u2192 gets wage 13, net payoff = 13 - 5 = 8\n Prefer Not Signal? 4 > 8? No \u2717\n- Separating equilibrium DOES NOT EXIST \u2717\n\n**Pooling Equilibrium** (Both signal or both don't):\n- If both signal: Receiver can't distinguish, offers pooling wage = 0.4\u00d713 + 0.6\u00d74 = 7.6\n High type net: 7.6 - 2 = 5.6\n Low type net: 7.6 - 5 = 2.6\n\n**Result:** No pure strategy PBE found with these parameters", | |
| "answer": "Equilibria: No pure strategy PBE found with these parameters", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "bayesian", | |
| "signaling", | |
| "incomplete_information", | |
| "perfect_bayesian", | |
| "separating", | |
| "pooling", | |
| "private_type" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-shapley-0118", | |
| "category": "cooperative_game", | |
| "subcategory": "shapley_value", | |
| "difficulty": "medium", | |
| "problem": "Calculate the Shapley value for each player in the following cooperative game:\n\nPlayers: {P1, P2, P3}\nCharacteristic function v(S):\n\n- v({P1}) = 9\n- v({P2}) = 19\n- v({P3}) = 17\n- v({P1, P2}) = 27\n- v({P1, P3}) = 26\n- v({P2, P3}) = 24\n- v({P1, P2, P3}) = 90", | |
| "solution": "**Shapley Value Computation:**\n\nThe Shapley value \u03c6\u1d62 assigns each player their average marginal contribution across all possible orderings.\n\nFormula: \u03c6\u1d62 = \u03a3 [|S|!(n-|S|-1)!/n!] \u00d7 [v(S\u222a{i}) - v(S)]\n\n**Player P1:**\n S=\u2205: v(S\u222aP1)=9 - v(S)=0 = 9, weight=0.3333\n S={P2}: v(S\u222aP1)=27 - v(S)=19 = 8, weight=0.1667\n S={P3}: v(S\u222aP1)=26 - v(S)=17 = 9, weight=0.1667\n S={P2, P3}: v(S\u222aP1)=90 - v(S)=24 = 66, weight=0.3333\n **\u03c6(P1) = 27.8333** \u2713\n\n**Player P2:**\n S=\u2205: v(S\u222aP2)=19 - v(S)=0 = 19, weight=0.3333\n S={P1}: v(S\u222aP2)=27 - v(S)=9 = 18, weight=0.1667\n S={P3}: v(S\u222aP2)=24 - v(S)=17 = 7, weight=0.1667\n S={P1, P3}: v(S\u222aP2)=90 - v(S)=26 = 64, weight=0.3333\n **\u03c6(P2) = 31.8333** \u2713\n\n**Player P3:**\n S=\u2205: v(S\u222aP3)=17 - v(S)=0 = 17, weight=0.3333\n S={P1}: v(S\u222aP3)=26 - v(S)=9 = 17, weight=0.1667\n S={P2}: v(S\u222aP3)=24 - v(S)=19 = 5, weight=0.1667\n S={P1, P2}: v(S\u222aP3)=90 - v(S)=27 = 63, weight=0.3333\n **\u03c6(P3) = 30.3333** \u2713\n\n**Efficiency check:** \u03a3\u03c6\u1d62 = 27.8333 + 31.8333 + 30.3333 = 89.9999\nv(N) = 90. Match \u2713", | |
| "answer": "\u03c6(P1)=27.8333, \u03c6(P2)=31.8333, \u03c6(P3)=30.3333", | |
| "game_type": "cooperative", | |
| "players": 3, | |
| "tags": [ | |
| "cooperative", | |
| "shapley_value", | |
| "coalition", | |
| "fair_division", | |
| "3_player", | |
| "characteristic_function" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-shapley-0053", | |
| "category": "cooperative_game", | |
| "subcategory": "shapley_value", | |
| "difficulty": "medium", | |
| "problem": "Calculate the Shapley value for each player in the following cooperative game:\n\nPlayers: {P1, P2, P3}\nCharacteristic function v(S):\n\n- v({P1}) = 17\n- v({P2}) = 15\n- v({P3}) = 14\n- v({P1, P2}) = 18\n- v({P1, P3}) = 40\n- v({P2, P3}) = 34\n- v({P1, P2, P3}) = 74", | |
| "solution": "**Shapley Value Computation:**\n\nThe Shapley value \u03c6\u1d62 assigns each player their average marginal contribution across all possible orderings.\n\nFormula: \u03c6\u1d62 = \u03a3 [|S|!(n-|S|-1)!/n!] \u00d7 [v(S\u222a{i}) - v(S)]\n\n**Player P1:**\n S=\u2205: v(S\u222aP1)=17 - v(S)=0 = 17, weight=0.3333\n S={P2}: v(S\u222aP1)=18 - v(S)=15 = 3, weight=0.1667\n S={P3}: v(S\u222aP1)=40 - v(S)=14 = 26, weight=0.1667\n S={P2, P3}: v(S\u222aP1)=74 - v(S)=34 = 40, weight=0.3333\n **\u03c6(P1) = 23.8333** \u2713\n\n**Player P2:**\n S=\u2205: v(S\u222aP2)=15 - v(S)=0 = 15, weight=0.3333\n S={P1}: v(S\u222aP2)=18 - v(S)=17 = 1, weight=0.1667\n S={P3}: v(S\u222aP2)=34 - v(S)=14 = 20, weight=0.1667\n S={P1, P3}: v(S\u222aP2)=74 - v(S)=40 = 34, weight=0.3333\n **\u03c6(P2) = 19.8333** \u2713\n\n**Player P3:**\n S=\u2205: v(S\u222aP3)=14 - v(S)=0 = 14, weight=0.3333\n S={P1}: v(S\u222aP3)=40 - v(S)=17 = 23, weight=0.1667\n S={P2}: v(S\u222aP3)=34 - v(S)=15 = 19, weight=0.1667\n S={P1, P2}: v(S\u222aP3)=74 - v(S)=18 = 56, weight=0.3333\n **\u03c6(P3) = 30.3333** \u2713\n\n**Efficiency check:** \u03a3\u03c6\u1d62 = 23.8333 + 19.8333 + 30.3333 = 73.9999\nv(N) = 74. Match \u2713", | |
| "answer": "\u03c6(P1)=23.8333, \u03c6(P2)=19.8333, \u03c6(P3)=30.3333", | |
| "game_type": "cooperative", | |
| "players": 3, | |
| "tags": [ | |
| "cooperative", | |
| "shapley_value", | |
| "coalition", | |
| "fair_division", | |
| "3_player", | |
| "characteristic_function" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-vote-0081", | |
| "category": "cooperative_game", | |
| "subcategory": "voting_power", | |
| "difficulty": "medium", | |
| "problem": "In this voting game:\n\nWeighted voting game [12; 15, 4, 1]\n- Quota to pass: 12\n- Total weight: 20\n- Voter 1: weight = 15\n- Voter 2: weight = 4\n- Voter 3: weight = 1\n\nDetermine each voter's power using the Shapley-Shubik index.", | |
| "solution": "**Shapley-Shubik Power Index:**\n\nCount how many orderings each voter is pivotal (brings total to \u2265 12).\n\n- Voter 1 (w=15): pivotal in 6/6 orderings \u2192 SSI = 1.0 (100.0%)\n- Voter 2 (w=4): pivotal in 0/6 orderings \u2192 SSI = 0.0 (0.0%)\n- Voter 3 (w=1): pivotal in 0/6 orderings \u2192 SSI = 0.0 (0.0%)\n\n**Power distribution:**\n Voter 1: \u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588 100.0%\n Voter 2: 0.0%\n Voter 3: 0.0%\n\nSum of SSI: 1.0000 \u2713\nNote: Voter 1 is a **dictator**.\nNote: Voter 1 has **veto power** (nothing passes without them).\nNote: Voter 2 is a **dummy** (zero power despite having weight).\nNote: Voter 3 is a **dummy** (zero power despite having weight).", | |
| "answer": "SSI(V1)=1.0, SSI(V2)=0.0, SSI(V3)=0.0", | |
| "game_type": "cooperative", | |
| "players": 3, | |
| "tags": [ | |
| "cooperative", | |
| "voting", | |
| "shapley_shubik", | |
| "power_index", | |
| "3_player", | |
| "weighted_voting" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-shapley-0005", | |
| "category": "cooperative_game", | |
| "subcategory": "shapley_value", | |
| "difficulty": "hard", | |
| "problem": "Determine a fair division using the Shapley value:\n\nPlayers: {P1, P2, P3, P4}\nCharacteristic function v(S):\n\n- v({P1}) = 2\n- v({P2}) = 7\n- v({P3}) = 6\n- v({P4}) = 4\n- v({P1, P2}) = 12\n- v({P1, P3}) = 7\n- v({P1, P4}) = 6\n- v({P2, P3}) = 15\n- v({P2, P4}) = 8\n- v({P3, P4}) = 9\n- v({P1, P2, P3}) = 35\n- v({P1, P2, P4}) = 27\n- v({P1, P3, P4}) = 34\n- v({P2, P3, P4}) = 35\n- v({P1, P2, P3, P4}) = 41\n\nWhat does each player receive?", | |
| "solution": "**Shapley Value Computation:**\n\nThe Shapley value \u03c6\u1d62 assigns each player their average marginal contribution across all possible orderings.\n\nFormula: \u03c6\u1d62 = \u03a3 [|S|!(n-|S|-1)!/n!] \u00d7 [v(S\u222a{i}) - v(S)]\n\n**Player P1:**\n S=\u2205: v(S\u222aP1)=2 - v(S)=0 = 2, weight=0.2500\n S={P2}: v(S\u222aP1)=12 - v(S)=7 = 5, weight=0.0833\n S={P3}: v(S\u222aP1)=7 - v(S)=6 = 1, weight=0.0833\n S={P4}: v(S\u222aP1)=6 - v(S)=4 = 2, weight=0.0833\n S={P2, P3}: v(S\u222aP1)=35 - v(S)=15 = 20, weight=0.0833\n S={P2, P4}: v(S\u222aP1)=27 - v(S)=8 = 19, weight=0.0833\n S={P3, P4}: v(S\u222aP1)=34 - v(S)=9 = 25, weight=0.0833\n S={P2, P3, P4}: v(S\u222aP1)=41 - v(S)=35 = 6, weight=0.2500\n **\u03c6(P1) = 8.0** \u2713\n\n**Player P2:**\n S=\u2205: v(S\u222aP2)=7 - v(S)=0 = 7, weight=0.2500\n S={P1}: v(S\u222aP2)=12 - v(S)=2 = 10, weight=0.0833\n S={P3}: v(S\u222aP2)=15 - v(S)=6 = 9, weight=0.0833\n S={P4}: v(S\u222aP2)=8 - v(S)=4 = 4, weight=0.0833\n S={P1, P3}: v(S\u222aP2)=35 - v(S)=7 = 28, weight=0.0833\n S={P1, P4}: v(S\u222aP2)=27 - v(S)=6 = 21, weight=0.0833\n S={P3, P4}: v(S\u222aP2)=35 - v(S)=9 = 26, weight=0.0833\n S={P1, P3, P4}: v(S\u222aP2)=41 - v(S)=34 = 7, weight=0.2500\n **\u03c6(P2) = 11.6667** \u2713\n\n**Player P3:**\n S=\u2205: v(S\u222aP3)=6 - v(S)=0 = 6, weight=0.2500\n S={P1}: v(S\u222aP3)=7 - v(S)=2 = 5, weight=0.0833\n S={P2}: v(S\u222aP3)=15 - v(S)=7 = 8, weight=0.0833\n S={P4}: v(S\u222aP3)=9 - v(S)=4 = 5, weight=0.0833\n S={P1, P2}: v(S\u222aP3)=35 - v(S)=12 = 23, weight=0.0833\n S={P1, P4}: v(S\u222aP3)=34 - v(S)=6 = 28, weight=0.0833\n S={P2, P4}: v(S\u222aP3)=35 - v(S)=8 = 27, weight=0.0833\n S={P1, P2, P4}: v(S\u222aP3)=41 - v(S)=27 = 14, weight=0.2500\n **\u03c6(P3) = 13.0** \u2713\n\n**Player P4:**\n S=\u2205: v(S\u222aP4)=4 - v(S)=0 = 4, weight=0.2500\n S={P1}: v(S\u222aP4)=6 - v(S)=2 = 4, weight=0.0833\n S={P2}: v(S\u222aP4)=8 - v(S)=7 = 1, weight=0.0833\n S={P3}: v(S\u222aP4)=9 - v(S)=6 = 3, weight=0.0833\n S={P1, P2}: v(S\u222aP4)=27 - v(S)=12 = 15, weight=0.0833\n S={P1, P3}: v(S\u222aP4)=34 - v(S)=7 = 27, weight=0.0833\n S={P2, P3}: v(S\u222aP4)=35 - v(S)=15 = 20, weight=0.0833\n S={P1, P2, P3}: v(S\u222aP4)=41 - v(S)=35 = 6, weight=0.2500\n **\u03c6(P4) = 8.3333** \u2713\n\n**Efficiency check:** \u03a3\u03c6\u1d62 = 8.0 + 11.6667 + 13.0 + 8.3333 = 41.0\nv(N) = 41. Match \u2713", | |
| "answer": "\u03c6(P1)=8.0, \u03c6(P2)=11.6667, \u03c6(P3)=13.0, \u03c6(P4)=8.3333", | |
| "game_type": "cooperative", | |
| "players": 4, | |
| "tags": [ | |
| "cooperative", | |
| "shapley_value", | |
| "coalition", | |
| "fair_division", | |
| "4_player", | |
| "characteristic_function" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-shapley-0112", | |
| "category": "cooperative_game", | |
| "subcategory": "shapley_value", | |
| "difficulty": "hard", | |
| "problem": "Calculate the Shapley value for each player in the following cooperative game:\n\nPlayers: {P1, P2, P3, P4}\nCharacteristic function v(S):\n\n- v({P1}) = 7\n- v({P2}) = 5\n- v({P3}) = 5\n- v({P4}) = 7\n- v({P1, P2}) = 9\n- v({P1, P3}) = 19\n- v({P1, P4}) = 15\n- v({P2, P3}) = 6\n- v({P2, P4}) = 12\n- v({P3, P4}) = 14\n- v({P1, P2, P3}) = 27\n- v({P1, P2, P4}) = 21\n- v({P1, P3, P4}) = 27\n- v({P2, P3, P4}) = 17\n- v({P1, P2, P3, P4}) = 29", | |
| "solution": "**Shapley Value Computation:**\n\nThe Shapley value \u03c6\u1d62 assigns each player their average marginal contribution across all possible orderings.\n\nFormula: \u03c6\u1d62 = \u03a3 [|S|!(n-|S|-1)!/n!] \u00d7 [v(S\u222a{i}) - v(S)]\n\n**Player P1:**\n S=\u2205: v(S\u222aP1)=7 - v(S)=0 = 7, weight=0.2500\n S={P2}: v(S\u222aP1)=9 - v(S)=5 = 4, weight=0.0833\n S={P3}: v(S\u222aP1)=19 - v(S)=5 = 14, weight=0.0833\n S={P4}: v(S\u222aP1)=15 - v(S)=7 = 8, weight=0.0833\n S={P2, P3}: v(S\u222aP1)=27 - v(S)=6 = 21, weight=0.0833\n S={P2, P4}: v(S\u222aP1)=21 - v(S)=12 = 9, weight=0.0833\n S={P3, P4}: v(S\u222aP1)=27 - v(S)=14 = 13, weight=0.0833\n S={P2, P3, P4}: v(S\u222aP1)=29 - v(S)=17 = 12, weight=0.2500\n **\u03c6(P1) = 10.5** \u2713\n\n**Player P2:**\n S=\u2205: v(S\u222aP2)=5 - v(S)=0 = 5, weight=0.2500\n S={P1}: v(S\u222aP2)=9 - v(S)=7 = 2, weight=0.0833\n S={P3}: v(S\u222aP2)=6 - v(S)=5 = 1, weight=0.0833\n S={P4}: v(S\u222aP2)=12 - v(S)=7 = 5, weight=0.0833\n S={P1, P3}: v(S\u222aP2)=27 - v(S)=19 = 8, weight=0.0833\n S={P1, P4}: v(S\u222aP2)=21 - v(S)=15 = 6, weight=0.0833\n S={P3, P4}: v(S\u222aP2)=17 - v(S)=14 = 3, weight=0.0833\n S={P1, P3, P4}: v(S\u222aP2)=29 - v(S)=27 = 2, weight=0.2500\n **\u03c6(P2) = 3.8333** \u2713\n\n**Player P3:**\n S=\u2205: v(S\u222aP3)=5 - v(S)=0 = 5, weight=0.2500\n S={P1}: v(S\u222aP3)=19 - v(S)=7 = 12, weight=0.0833\n S={P2}: v(S\u222aP3)=6 - v(S)=5 = 1, weight=0.0833\n S={P4}: v(S\u222aP3)=14 - v(S)=7 = 7, weight=0.0833\n S={P1, P2}: v(S\u222aP3)=27 - v(S)=9 = 18, weight=0.0833\n S={P1, P4}: v(S\u222aP3)=27 - v(S)=15 = 12, weight=0.0833\n S={P2, P4}: v(S\u222aP3)=17 - v(S)=12 = 5, weight=0.0833\n S={P1, P2, P4}: v(S\u222aP3)=29 - v(S)=21 = 8, weight=0.2500\n **\u03c6(P3) = 7.8333** \u2713\n\n**Player P4:**\n S=\u2205: v(S\u222aP4)=7 - v(S)=0 = 7, weight=0.2500\n S={P1}: v(S\u222aP4)=15 - v(S)=7 = 8, weight=0.0833\n S={P2}: v(S\u222aP4)=12 - v(S)=5 = 7, weight=0.0833\n S={P3}: v(S\u222aP4)=14 - v(S)=5 = 9, weight=0.0833\n S={P1, P2}: v(S\u222aP4)=21 - v(S)=9 = 12, weight=0.0833\n S={P1, P3}: v(S\u222aP4)=27 - v(S)=19 = 8, weight=0.0833\n S={P2, P3}: v(S\u222aP4)=17 - v(S)=6 = 11, weight=0.0833\n S={P1, P2, P3}: v(S\u222aP4)=29 - v(S)=27 = 2, weight=0.2500\n **\u03c6(P4) = 6.8333** \u2713\n\n**Efficiency check:** \u03a3\u03c6\u1d62 = 10.5 + 3.8333 + 7.8333 + 6.8333 = 28.9999\nv(N) = 29. Match \u2713", | |
| "answer": "\u03c6(P1)=10.5, \u03c6(P2)=3.8333, \u03c6(P3)=7.8333, \u03c6(P4)=6.8333", | |
| "game_type": "cooperative", | |
| "players": 4, | |
| "tags": [ | |
| "cooperative", | |
| "shapley_value", | |
| "coalition", | |
| "fair_division", | |
| "4_player", | |
| "characteristic_function" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-vote-0082", | |
| "category": "cooperative_game", | |
| "subcategory": "voting_power", | |
| "difficulty": "hard", | |
| "problem": "In this voting game:\n\nWeighted voting game [19; 14, 7, 5, 1]\n- Quota to pass: 19\n- Total weight: 27\n- Voter 1: weight = 14\n- Voter 2: weight = 7\n- Voter 3: weight = 5\n- Voter 4: weight = 1\n\nDetermine each voter's power using the Shapley-Shubik index.", | |
| "solution": "**Shapley-Shubik Power Index:**\n\nCount how many orderings each voter is pivotal (brings total to \u2265 19).\n\n- Voter 1 (w=14): pivotal in 16/24 orderings \u2192 SSI = 0.6667 (66.7%)\n- Voter 2 (w=7): pivotal in 4/24 orderings \u2192 SSI = 0.1667 (16.7%)\n- Voter 3 (w=5): pivotal in 4/24 orderings \u2192 SSI = 0.1667 (16.7%)\n- Voter 4 (w=1): pivotal in 0/24 orderings \u2192 SSI = 0.0 (0.0%)\n\n**Power distribution:**\n Voter 1: \u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588 66.7%\n Voter 2: \u2588\u2588\u2588\u2588\u2588\u2588 16.7%\n Voter 3: \u2588\u2588\u2588\u2588\u2588\u2588 16.7%\n Voter 4: 0.0%\n\nSum of SSI: 1.0001 \u2713\nNote: Voter 1 has **veto power** (nothing passes without them).\nNote: Voter 4 is a **dummy** (zero power despite having weight).", | |
| "answer": "SSI(V1)=0.6667, SSI(V2)=0.1667, SSI(V3)=0.1667, SSI(V4)=0.0", | |
| "game_type": "cooperative", | |
| "players": 4, | |
| "tags": [ | |
| "cooperative", | |
| "voting", | |
| "shapley_shubik", | |
| "power_index", | |
| "4_player", | |
| "weighted_voting" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-vote-0020", | |
| "category": "cooperative_game", | |
| "subcategory": "voting_power", | |
| "difficulty": "hard", | |
| "problem": "Consider the following weighted voting game:\n\nWeighted voting game [24; 13, 12, 11, 5, 4]\n- Quota to pass: 24\n- Total weight: 45\n- Voter 1: weight = 13\n- Voter 2: weight = 12\n- Voter 3: weight = 11\n- Voter 4: weight = 5\n- Voter 5: weight = 4\n\nCompute the Shapley-Shubik power index for each player.", | |
| "solution": "**Shapley-Shubik Power Index:**\n\nCount how many orderings each voter is pivotal (brings total to \u2265 24).\n\n- Voter 1 (w=13): pivotal in 44/120 orderings \u2192 SSI = 0.3667 (36.7%)\n- Voter 2 (w=12): pivotal in 34/120 orderings \u2192 SSI = 0.2833 (28.3%)\n- Voter 3 (w=11): pivotal in 34/120 orderings \u2192 SSI = 0.2833 (28.3%)\n- Voter 4 (w=5): pivotal in 4/120 orderings \u2192 SSI = 0.0333 (3.3%)\n- Voter 5 (w=4): pivotal in 4/120 orderings \u2192 SSI = 0.0333 (3.3%)\n\n**Power distribution:**\n Voter 1: \u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588 36.7%\n Voter 2: \u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588 28.3%\n Voter 3: \u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588\u2588 28.3%\n Voter 4: \u2588 3.3%\n Voter 5: \u2588 3.3%\n\nSum of SSI: 0.9999 \u2713", | |
| "answer": "SSI(V1)=0.3667, SSI(V2)=0.2833, SSI(V3)=0.2833, SSI(V4)=0.0333, SSI(V5)=0.0333", | |
| "game_type": "cooperative", | |
| "players": 5, | |
| "tags": [ | |
| "cooperative", | |
| "voting", | |
| "shapley_shubik", | |
| "power_index", | |
| "5_player", | |
| "weighted_voting" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-core-0058", | |
| "category": "cooperative_game", | |
| "subcategory": "core_analysis", | |
| "difficulty": "hard", | |
| "problem": "Analyze the core of this coalition game:\n\nPlayers: {P1, P2, P3}\nCharacteristic function:\n- v({P1}) = 1, v({P2}) = 14, v({P3}) = 1\n- v({P1,P2}) = 29, v({P1,P3}) = 48, v({P2,P3}) = 16\n- v({P1,P2,P3}) = 48\n\nIs the core non-empty? If so, describe it.", | |
| "solution": "**Core Analysis:**\n\nThe core is the set of allocations (x1,x2,x3) such that:\n1. x1 + x2 + x3 = 48 (efficiency)\n2. x1 \u2265 1, x2 \u2265 14, x3 \u2265 1 (individual rationality)\n3. x1+x2 \u2265 29, x1+x3 \u2265 48, x2+x3 \u2265 16 (coalition rationality)\n\nFrom efficiency + coalition rationality:\n- x1 \u2264 48 - 16 = 32\n- x2 \u2264 48 - 48 = 0\n- x3 \u2264 48 - 29 = 19\n\nBounds: 1 \u2264 x1 \u2264 32, 14 \u2264 x2 \u2264 0, 1 \u2264 x3 \u2264 19\n\nThe core is **empty** \u2717", | |
| "answer": "Core empty. Bounds: 1\u2264x1\u226432, 14\u2264x2\u22640, 1\u2264x3\u226419", | |
| "game_type": "cooperative", | |
| "players": 3, | |
| "tags": [ | |
| "cooperative", | |
| "core", | |
| "coalition", | |
| "stability", | |
| "3_player", | |
| "characteristic_function" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-core-0026", | |
| "category": "cooperative_game", | |
| "subcategory": "core_analysis", | |
| "difficulty": "hard", | |
| "problem": "Analyze the core of this coalition game:\n\nPlayers: {P1, P2, P3}\nCharacteristic function:\n- v({P1}) = 12, v({P2}) = 12, v({P3}) = 11\n- v({P1,P2}) = 21, v({P1,P3}) = 30, v({P2,P3}) = 14\n- v({P1,P2,P3}) = 46\n\nIs the core non-empty? If so, describe it.", | |
| "solution": "**Core Analysis:**\n\nThe core is the set of allocations (x1,x2,x3) such that:\n1. x1 + x2 + x3 = 46 (efficiency)\n2. x1 \u2265 12, x2 \u2265 12, x3 \u2265 11 (individual rationality)\n3. x1+x2 \u2265 21, x1+x3 \u2265 30, x2+x3 \u2265 14 (coalition rationality)\n\nFrom efficiency + coalition rationality:\n- x1 \u2264 46 - 14 = 32\n- x2 \u2264 46 - 30 = 16\n- x3 \u2264 46 - 21 = 25\n\nBounds: 12 \u2264 x1 \u2264 32, 12 \u2264 x2 \u2264 16, 11 \u2264 x3 \u2264 25\n\nThe core is **non-empty** \u2713\nSum of lower bounds: 35 \u2264 46 \u2713\nAll upper \u2265 lower: True \u2713", | |
| "answer": "Core non-empty. Bounds: 12\u2264x1\u226432, 12\u2264x2\u226416, 11\u2264x3\u226425", | |
| "game_type": "cooperative", | |
| "players": 3, | |
| "tags": [ | |
| "cooperative", | |
| "core", | |
| "coalition", | |
| "stability", | |
| "3_player", | |
| "characteristic_function" | |
| ] | |
| }, | |
| { | |
| "id": "gt-coop-shapley-0081", | |
| "category": "cooperative_game", | |
| "subcategory": "shapley_value", | |
| "difficulty": "medium", | |
| "problem": "Determine a fair division using the Shapley value:\n\nPlayers: {P1, P2, P3}\nCharacteristic function v(S):\n\n- v({P1}) = 4\n- v({P2}) = 17\n- v({P3}) = 1\n- v({P1, P2}) = 27\n- v({P1, P3}) = 7\n- v({P2, P3}) = 27\n- v({P1, P2, P3}) = 57\n\nWhat does each player receive?", | |
| "solution": "**Shapley Value Computation:**\n\nThe Shapley value \u03c6\u1d62 assigns each player their average marginal contribution across all possible orderings.\n\nFormula: \u03c6\u1d62 = \u03a3 [|S|!(n-|S|-1)!/n!] \u00d7 [v(S\u222a{i}) - v(S)]\n\n**Player P1:**\n S=\u2205: v(S\u222aP1)=4 - v(S)=0 = 4, weight=0.3333\n S={P2}: v(S\u222aP1)=27 - v(S)=17 = 10, weight=0.1667\n S={P3}: v(S\u222aP1)=7 - v(S)=1 = 6, weight=0.1667\n S={P2, P3}: v(S\u222aP1)=57 - v(S)=27 = 30, weight=0.3333\n **\u03c6(P1) = 14.0** \u2713\n\n**Player P2:**\n S=\u2205: v(S\u222aP2)=17 - v(S)=0 = 17, weight=0.3333\n S={P1}: v(S\u222aP2)=27 - v(S)=4 = 23, weight=0.1667\n S={P3}: v(S\u222aP2)=27 - v(S)=1 = 26, weight=0.1667\n S={P1, P3}: v(S\u222aP2)=57 - v(S)=7 = 50, weight=0.3333\n **\u03c6(P2) = 30.5** \u2713\n\n**Player P3:**\n S=\u2205: v(S\u222aP3)=1 - v(S)=0 = 1, weight=0.3333\n S={P1}: v(S\u222aP3)=7 - v(S)=4 = 3, weight=0.1667\n S={P2}: v(S\u222aP3)=27 - v(S)=17 = 10, weight=0.1667\n S={P1, P2}: v(S\u222aP3)=57 - v(S)=27 = 30, weight=0.3333\n **\u03c6(P3) = 12.5** \u2713\n\n**Efficiency check:** \u03a3\u03c6\u1d62 = 14.0 + 30.5 + 12.5 = 57.0\nv(N) = 57. Match \u2713", | |
| "answer": "\u03c6(P1)=14.0, \u03c6(P2)=30.5, \u03c6(P3)=12.5", | |
| "game_type": "cooperative", | |
| "players": 3, | |
| "tags": [ | |
| "cooperative", | |
| "shapley_value", | |
| "coalition", | |
| "fair_division", | |
| "3_player", | |
| "characteristic_function" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcg1-0055", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_single_item", | |
| "difficulty": "medium", | |
| "problem": "Consider a VCG (Vickrey-Clarke-Groves) mechanism for the following allocation problem:\n\n6 agents compete for a single indivisible item.\nEach agent has a private valuation:\n- Agent 1: v = 78\n- Agent 2: v = 85\n- Agent 3: v = 14\n- Agent 4: v = 58\n- Agent 5: v = 63\n- Agent 6: v = 83\n\nThe mechanism allocates the item to maximize total welfare and charges VCG payments.\n\nCompute the VCG payments and final allocation.", | |
| "solution": "**VCG Mechanism for Single Item Allocation:**\n\nStep 1: **Efficient allocation** - give item to highest-value agent.\n- Agent 2 has highest valuation (85). \u2713\n\nStep 2: **VCG Payment** - winner pays the externality imposed on others.\n- Without Agent 2: next highest (83) would get the item.\n- Others' welfare WITH Agent 2: 0 (they don't get item)\n- Others' welfare WITHOUT Agent 2: 83 (next agent gets item)\n- VCG payment = 83 - 0 = **83**\n\n**Result:**\n- Winner: Agent 2 (value 85)\n- Payment: 83\n- Surplus: 2\n- All other agents: pay 0, receive nothing.\n\n**Note:** VCG for single item reduces to Vickrey (second-price) auction. \u2713\nTruthful reporting is a dominant strategy. \u2713", | |
| "answer": "Winner: Agent 2 (v=85), Payment: 83, Surplus: 2", | |
| "game_type": "mechanism", | |
| "players": 6, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "incentive_compatible", | |
| "dominant_strategy", | |
| "efficient_allocation", | |
| "6_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-ic-0006", | |
| "category": "mechanism_design", | |
| "subcategory": "incentive_compatibility", | |
| "difficulty": "medium", | |
| "problem": "Determine whether the following mechanism is incentive compatible:\n\nMechanism: Median voter mechanism\nRule: Each agent reports preferred level. Outcome is the median of reports.\nNumber of agents: 4\nAgent valuations: v1=41, v2=23, v3=49, v4=23\n\nCheck if truthful reporting is a dominant strategy.", | |
| "solution": "**Incentive Compatibility Analysis of Median voter mechanism:**\n\nA mechanism is **incentive compatible (IC)** if truthful reporting is a dominant strategy \u2014 no agent benefits from misreporting regardless of others' reports.\n\n**Mechanism rule:** Each agent reports preferred level. Outcome is the median of reports.\n\n**Is it IC?** Yes \u2713\n\n**Reasoning:** The median mechanism is strategy-proof for single-peaked preferences. No agent can move the median closer to their peak by misreporting.", | |
| "answer": "Median voter mechanism: IC \u2713", | |
| "game_type": "mechanism", | |
| "players": 4, | |
| "tags": [ | |
| "mechanism_design", | |
| "incentive_compatibility", | |
| "strategy_proof", | |
| "revelation_principle", | |
| "4_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcg1-0026", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_single_item", | |
| "difficulty": "medium", | |
| "problem": "Apply the VCG mechanism to determine the efficient allocation and payments:\n\n4 agents compete for a single indivisible item.\nEach agent has a private valuation:\n- Agent 1: v = 66\n- Agent 2: v = 57\n- Agent 3: v = 67\n- Agent 4: v = 32\n\nThe mechanism allocates the item to maximize total welfare and charges VCG payments.", | |
| "solution": "**VCG Mechanism for Single Item Allocation:**\n\nStep 1: **Efficient allocation** - give item to highest-value agent.\n- Agent 3 has highest valuation (67). \u2713\n\nStep 2: **VCG Payment** - winner pays the externality imposed on others.\n- Without Agent 3: next highest (66) would get the item.\n- Others' welfare WITH Agent 3: 0 (they don't get item)\n- Others' welfare WITHOUT Agent 3: 66 (next agent gets item)\n- VCG payment = 66 - 0 = **66**\n\n**Result:**\n- Winner: Agent 3 (value 67)\n- Payment: 66\n- Surplus: 1\n- All other agents: pay 0, receive nothing.\n\n**Note:** VCG for single item reduces to Vickrey (second-price) auction. \u2713\nTruthful reporting is a dominant strategy. \u2713", | |
| "answer": "Winner: Agent 3 (v=67), Payment: 66, Surplus: 1", | |
| "game_type": "mechanism", | |
| "players": 4, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "incentive_compatible", | |
| "dominant_strategy", | |
| "efficient_allocation", | |
| "4_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcgm-0005", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_multi_item", | |
| "difficulty": "hard", | |
| "problem": "Consider a VCG (Vickrey-Clarke-Groves) mechanism for the following allocation problem:\n\n3 agents, 2 items (Item A, Item B).\nEach agent's valuation:\n\nAgent | Item A | Item B\n--- | --- | ---\nAgent 1 | 13 | 16\nAgent 2 | 3 | 19\nAgent 3 | 21 | 22\n\nEach item is allocated to one agent to maximize total welfare. VCG payments apply.\n\nCompute the VCG payments and final allocation.", | |
| "solution": "**VCG Mechanism for Multi-Item Allocation:**\n\n**Step 1: Efficient allocation (maximize total welfare):**\n- Item A: highest value is Agent 3 (21). [Agent 1=13, Agent 2=3, Agent 3=21]\n- Item B: highest value is Agent 3 (22). [Agent 1=16, Agent 2=19, Agent 3=22]\n- Total welfare: 43\n\n**Step 2: VCG payments (externality on others):**\n- Agent 1: wins nothing, payment = 0 \u2713\n- Agent 2: wins nothing, payment = 0 \u2713\n- Agent 3 (wins Item A, Item B):\n Others' welfare with Agent 3: 0\n Others' welfare without Agent 3: 32\n Payment = 32 - 0 = **32** \u2713\n\n**Summary:**\n- Agent 1: gets nothing, value=0, pays=0, net=0\n- Agent 2: gets nothing, value=0, pays=0, net=0\n- Agent 3: gets ['Item A', 'Item B'], value=43, pays=32, net=11", | |
| "answer": "Item A\u2192Agent 3; Item B\u2192Agent 3; Payments: A1=0, A2=0, A3=32", | |
| "game_type": "mechanism", | |
| "players": 3, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "multi_item", | |
| "incentive_compatible", | |
| "efficient_allocation", | |
| "3_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcgm-0024", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_multi_item", | |
| "difficulty": "hard", | |
| "problem": "Using the Vickrey-Clarke-Groves mechanism, find the optimal allocation and each agent's payment:\n\n3 agents, 2 items (Item A, Item B).\nEach agent's valuation:\n\nAgent | Item A | Item B\n--- | --- | ---\nAgent 1 | 2 | 25\nAgent 2 | 25 | 6\nAgent 3 | 16 | 17\n\nEach item is allocated to one agent to maximize total welfare. VCG payments apply.", | |
| "solution": "**VCG Mechanism for Multi-Item Allocation:**\n\n**Step 1: Efficient allocation (maximize total welfare):**\n- Item A: highest value is Agent 2 (25). [Agent 1=2, Agent 2=25, Agent 3=16]\n- Item B: highest value is Agent 1 (25). [Agent 1=25, Agent 2=6, Agent 3=17]\n- Total welfare: 50\n\n**Step 2: VCG payments (externality on others):**\n- Agent 1 (wins Item B):\n Others' welfare with Agent 1: 25\n Others' welfare without Agent 1: 42\n Payment = 42 - 25 = **17** \u2713\n- Agent 2 (wins Item A):\n Others' welfare with Agent 2: 25\n Others' welfare without Agent 2: 41\n Payment = 41 - 25 = **16** \u2713\n- Agent 3: wins nothing, payment = 0 \u2713\n\n**Summary:**\n- Agent 1: gets ['Item B'], value=25, pays=17, net=8\n- Agent 2: gets ['Item A'], value=25, pays=16, net=9\n- Agent 3: gets nothing, value=0, pays=0, net=0", | |
| "answer": "Item A\u2192Agent 2; Item B\u2192Agent 1; Payments: A1=17, A2=16, A3=0", | |
| "game_type": "mechanism", | |
| "players": 3, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "multi_item", | |
| "incentive_compatible", | |
| "efficient_allocation", | |
| "3_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcgm-0006", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_multi_item", | |
| "difficulty": "hard", | |
| "problem": "Consider a VCG (Vickrey-Clarke-Groves) mechanism for the following allocation problem:\n\n3 agents, 2 items (Item A, Item B).\nEach agent's valuation:\n\nAgent | Item A | Item B\n--- | --- | ---\nAgent 1 | 5 | 5\nAgent 2 | 26 | 19\nAgent 3 | 10 | 3\n\nEach item is allocated to one agent to maximize total welfare. VCG payments apply.\n\nCompute the VCG payments and final allocation.", | |
| "solution": "**VCG Mechanism for Multi-Item Allocation:**\n\n**Step 1: Efficient allocation (maximize total welfare):**\n- Item A: highest value is Agent 2 (26). [Agent 1=5, Agent 2=26, Agent 3=10]\n- Item B: highest value is Agent 2 (19). [Agent 1=5, Agent 2=19, Agent 3=3]\n- Total welfare: 45\n\n**Step 2: VCG payments (externality on others):**\n- Agent 1: wins nothing, payment = 0 \u2713\n- Agent 2 (wins Item A, Item B):\n Others' welfare with Agent 2: 0\n Others' welfare without Agent 2: 15\n Payment = 15 - 0 = **15** \u2713\n- Agent 3: wins nothing, payment = 0 \u2713\n\n**Summary:**\n- Agent 1: gets nothing, value=0, pays=0, net=0\n- Agent 2: gets ['Item A', 'Item B'], value=45, pays=15, net=30\n- Agent 3: gets nothing, value=0, pays=0, net=0", | |
| "answer": "Item A\u2192Agent 2; Item B\u2192Agent 2; Payments: A1=0, A2=15, A3=0", | |
| "game_type": "mechanism", | |
| "players": 3, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "multi_item", | |
| "incentive_compatible", | |
| "efficient_allocation", | |
| "3_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcgm-0015", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_multi_item", | |
| "difficulty": "hard", | |
| "problem": "Using the Vickrey-Clarke-Groves mechanism, find the optimal allocation and each agent's payment:\n\n3 agents, 2 items (Item A, Item B).\nEach agent's valuation:\n\nAgent | Item A | Item B\n--- | --- | ---\nAgent 1 | 30 | 9\nAgent 2 | 26 | 26\nAgent 3 | 21 | 19\n\nEach item is allocated to one agent to maximize total welfare. VCG payments apply.", | |
| "solution": "**VCG Mechanism for Multi-Item Allocation:**\n\n**Step 1: Efficient allocation (maximize total welfare):**\n- Item A: highest value is Agent 1 (30). [Agent 1=30, Agent 2=26, Agent 3=21]\n- Item B: highest value is Agent 2 (26). [Agent 1=9, Agent 2=26, Agent 3=19]\n- Total welfare: 56\n\n**Step 2: VCG payments (externality on others):**\n- Agent 1 (wins Item A):\n Others' welfare with Agent 1: 26\n Others' welfare without Agent 1: 52\n Payment = 52 - 26 = **26** \u2713\n- Agent 2 (wins Item B):\n Others' welfare with Agent 2: 30\n Others' welfare without Agent 2: 49\n Payment = 49 - 30 = **19** \u2713\n- Agent 3: wins nothing, payment = 0 \u2713\n\n**Summary:**\n- Agent 1: gets ['Item A'], value=30, pays=26, net=4\n- Agent 2: gets ['Item B'], value=26, pays=19, net=7\n- Agent 3: gets nothing, value=0, pays=0, net=0", | |
| "answer": "Item A\u2192Agent 1; Item B\u2192Agent 2; Payments: A1=26, A2=19, A3=0", | |
| "game_type": "mechanism", | |
| "players": 3, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "multi_item", | |
| "incentive_compatible", | |
| "efficient_allocation", | |
| "3_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcgm-0012", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_multi_item", | |
| "difficulty": "hard", | |
| "problem": "Using the Vickrey-Clarke-Groves mechanism, find the optimal allocation and each agent's payment:\n\n3 agents, 2 items (Item A, Item B).\nEach agent's valuation:\n\nAgent | Item A | Item B\n--- | --- | ---\nAgent 1 | 18 | 3\nAgent 2 | 6 | 1\nAgent 3 | 14 | 15\n\nEach item is allocated to one agent to maximize total welfare. VCG payments apply.", | |
| "solution": "**VCG Mechanism for Multi-Item Allocation:**\n\n**Step 1: Efficient allocation (maximize total welfare):**\n- Item A: highest value is Agent 1 (18). [Agent 1=18, Agent 2=6, Agent 3=14]\n- Item B: highest value is Agent 3 (15). [Agent 1=3, Agent 2=1, Agent 3=15]\n- Total welfare: 33\n\n**Step 2: VCG payments (externality on others):**\n- Agent 1 (wins Item A):\n Others' welfare with Agent 1: 15\n Others' welfare without Agent 1: 29\n Payment = 29 - 15 = **14** \u2713\n- Agent 2: wins nothing, payment = 0 \u2713\n- Agent 3 (wins Item B):\n Others' welfare with Agent 3: 18\n Others' welfare without Agent 3: 21\n Payment = 21 - 18 = **3** \u2713\n\n**Summary:**\n- Agent 1: gets ['Item A'], value=18, pays=14, net=4\n- Agent 2: gets nothing, value=0, pays=0, net=0\n- Agent 3: gets ['Item B'], value=15, pays=3, net=12", | |
| "answer": "Item A\u2192Agent 1; Item B\u2192Agent 3; Payments: A1=14, A2=0, A3=3", | |
| "game_type": "mechanism", | |
| "players": 3, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "multi_item", | |
| "incentive_compatible", | |
| "efficient_allocation", | |
| "3_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-ic-0020", | |
| "category": "mechanism_design", | |
| "subcategory": "incentive_compatibility", | |
| "difficulty": "medium", | |
| "problem": "Analyze the incentive compatibility of this mechanism:\n\nMechanism: First-price auction\nRule: Highest bidder wins, pays their bid.\nNumber of agents: 2\nAgent valuations: v1=20, v2=39\n\nWould any agent benefit from misreporting?", | |
| "solution": "**Incentive Compatibility Analysis of First-price auction:**\n\nA mechanism is **incentive compatible (IC)** if truthful reporting is a dominant strategy \u2014 no agent benefits from misreporting regardless of others' reports.\n\n**Mechanism rule:** Highest bidder wins, pays their bid.\n\n**Is it IC?** No \u2717\n\n**Reasoning:** Bidders have incentive to shade bids below true value to increase surplus. Truthful bidding is NOT a dominant strategy.\n\n**Example:** Agent with value 39 bids 36 instead of 39:\n- If they win at 36: surplus = 39 - 36 = 3 (better than 0 surplus from truthful bid)\n- Rational agents shade bids below true values. \u2713", | |
| "answer": "First-price auction: NOT IC \u2717", | |
| "game_type": "mechanism", | |
| "players": 2, | |
| "tags": [ | |
| "mechanism_design", | |
| "incentive_compatibility", | |
| "strategy_proof", | |
| "revelation_principle", | |
| "2_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-mech-vcg1-0069", | |
| "category": "mechanism_design", | |
| "subcategory": "vcg_single_item", | |
| "difficulty": "medium", | |
| "problem": "Using the Vickrey-Clarke-Groves mechanism, find the optimal allocation and each agent's payment:\n\n4 agents compete for a single indivisible item.\nEach agent has a private valuation:\n- Agent 1: v = 80\n- Agent 2: v = 14\n- Agent 3: v = 93\n- Agent 4: v = 85\n\nThe mechanism allocates the item to maximize total welfare and charges VCG payments.", | |
| "solution": "**VCG Mechanism for Single Item Allocation:**\n\nStep 1: **Efficient allocation** - give item to highest-value agent.\n- Agent 3 has highest valuation (93). \u2713\n\nStep 2: **VCG Payment** - winner pays the externality imposed on others.\n- Without Agent 3: next highest (85) would get the item.\n- Others' welfare WITH Agent 3: 0 (they don't get item)\n- Others' welfare WITHOUT Agent 3: 85 (next agent gets item)\n- VCG payment = 85 - 0 = **85**\n\n**Result:**\n- Winner: Agent 3 (value 93)\n- Payment: 85\n- Surplus: 8\n- All other agents: pay 0, receive nothing.\n\n**Note:** VCG for single item reduces to Vickrey (second-price) auction. \u2713\nTruthful reporting is a dominant strategy. \u2713", | |
| "answer": "Winner: Agent 3 (v=93), Payment: 85, Surplus: 8", | |
| "game_type": "mechanism", | |
| "players": 4, | |
| "tags": [ | |
| "mechanism_design", | |
| "vcg", | |
| "incentive_compatible", | |
| "dominant_strategy", | |
| "efficient_allocation", | |
| "4_agents" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-classic-scaled-0023", | |
| "category": "normal_form_2x2", | |
| "subcategory": "classic_stag_hunt_scaled", | |
| "difficulty": "easy", | |
| "problem": "Given the following payoff matrix for a two-player simultaneous game:\n\nPlayer 1 \\ Player 2 | Stag | Hare\n--- | --- | ---\nStag | (12,12) | (0,9)\nHare | (9,0) | (9,9)\n\nWhat are the Nash Equilibria?", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Up, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff 12. If Player 1 switches to Down (while Player 2 stays at Left), payoff drops to 9. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 12. If Player 2 switches to Right (while Player 1 stays at Up), payoff drops to 9. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Left) is a Nash Equilibrium with payoffs (12,12).\n\nTo verify (Down, Right) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Down, getting payoff 9. If Player 1 switches to Up (while Player 2 stays at Right), payoff drops to 0. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 9. If Player 2 switches to Left (while Player 1 stays at Down), payoff drops to 0. Player 2 has no incentive to deviate. \u2713\nTherefore (Down, Right) is a Nash Equilibrium with payoffs (9,9).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Up with probability 0.7500, Down with probability 0.2500.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.7500, Right with probability 0.2500.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 9.0000, Player 2 gets 9.0000.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Up, Left), (Down, Right), P1=[Up:0.7500, Down:0.2500], P2=[Left:0.7500, Right:0.2500]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "classic_game", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy", | |
| "scaled", | |
| "stag_hunt" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-wide-0026", | |
| "category": "normal_form_2x2", | |
| "subcategory": "random_payoffs", | |
| "difficulty": "easy", | |
| "problem": "Analyze the following strategic form game and determine all Nash Equilibria:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (4,0) | (10,-2)\nDown | (-8,-6) | (6,-1)", | |
| "solution": "This game has 1 pure strategy Nash Equilibrium.\n\nTo verify (Up, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff 4. If Player 1 switches to Down (while Player 2 stays at Left), payoff drops to -8. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 0. If Player 2 switches to Right (while Player 1 stays at Up), payoff drops to -2. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Left) is a Nash Equilibrium with payoffs (4,0).\n\nThere are no additional mixed strategy equilibria beyond the pure strategy equilibrium identified above.", | |
| "answer": "[(Up, Left)]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "dominant_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-wide-0068", | |
| "category": "normal_form_2x2", | |
| "subcategory": "random_payoffs", | |
| "difficulty": "easy", | |
| "problem": "Given the following payoff matrix for a two-player simultaneous game:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (5,0) | (-1,-1)\nDown | (5,-7) | (-4,7)\n\nWhat are the Nash Equilibria?", | |
| "solution": "This game has 1 pure strategy Nash Equilibrium.\n\nTo verify (Up, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff 5. If Player 1 switches to Down (while Player 2 stays at Left), payoff stays at 5. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 0. If Player 2 switches to Right (while Player 1 stays at Up), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Left) is a Nash Equilibrium with payoffs (5,0).\n\nThere are no additional mixed strategy equilibria beyond the pure strategy equilibrium identified above.", | |
| "answer": "[(Up, Left)]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "dominant_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-pure-ne-0110", | |
| "category": "normal_form_2x2", | |
| "subcategory": "pure_nash_equilibrium", | |
| "difficulty": "medium", | |
| "problem": "In the game represented by the payoff matrix below, find every Nash Equilibrium:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (3,-1) | (-1,-1)\nDown | (-3,-3) | (-1,5)", | |
| "solution": "This game has 3 pure strategy Nash Equilibria.\n\nTo verify (Up, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff 3. If Player 1 switches to Down (while Player 2 stays at Left), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff -1. If Player 2 switches to Right (while Player 1 stays at Up), payoff stays at -1. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Left) is a Nash Equilibrium with payoffs (3,-1).\n\nTo verify (Up, Right) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff -1. If Player 1 switches to Down (while Player 2 stays at Right), payoff stays at -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff -1. If Player 2 switches to Left (while Player 1 stays at Up), payoff stays at -1. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Right) is a Nash Equilibrium with payoffs (-1,-1).\n\nTo verify (Down, Right) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Down, getting payoff -1. If Player 1 switches to Up (while Player 2 stays at Right), payoff stays at -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 5. If Player 2 switches to Left (while Player 1 stays at Down), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\nTherefore (Down, Right) is a Nash Equilibrium with payoffs (-1,5).\n\nThere are no additional mixed strategy equilibria beyond the pure strategy equilibria identified above.", | |
| "answer": "[(Up, Left), (Up, Right), (Down, Right)]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-mixed-ne-0060", | |
| "category": "normal_form_2x2", | |
| "subcategory": "mixed_nash_equilibrium", | |
| "difficulty": "medium", | |
| "problem": "In the following game, players must randomize. Find the mixed strategy Nash Equilibrium and expected payoffs:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (1,-4) | (2,2)\nDown | (-3,2) | (3,-2)", | |
| "solution": "There are no pure strategy Nash Equilibria.\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Up with probability 0.4000, Down with probability 0.6000.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.2000, Right with probability 0.8000.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 1.8000, Player 2 gets -0.4000.", | |
| "answer": "[P1=[Up:0.4000, Down:0.6000], P2=[Left:0.2000, Right:0.8000]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-pure-ne-0066", | |
| "category": "normal_form_2x2", | |
| "subcategory": "pure_nash_equilibrium", | |
| "difficulty": "medium", | |
| "problem": "Given the following payoff matrix for a two-player simultaneous game:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (1,4) | (3,4)\nDown | (1,1) | (-1,4)\n\nWhat are the Nash Equilibria?", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Up, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff 1. If Player 1 switches to Down (while Player 2 stays at Left), payoff stays at 1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 4. If Player 2 switches to Right (while Player 1 stays at Up), payoff stays at 4. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Left) is a Nash Equilibrium with payoffs (1,4).\n\nTo verify (Up, Right) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff 3. If Player 1 switches to Down (while Player 2 stays at Right), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 4. If Player 2 switches to Left (while Player 1 stays at Up), payoff stays at 4. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Right) is a Nash Equilibrium with payoffs (3,4).\n\nThere are no additional mixed strategy equilibria beyond the pure strategy equilibria identified above.", | |
| "answer": "[(Up, Left), (Up, Right)]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-dom-strat-0037", | |
| "category": "normal_form_2x2", | |
| "subcategory": "dominant_strategy", | |
| "difficulty": "easy", | |
| "problem": "Consider the game below:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (-4,5) | (-2,3)\nDown | (2,1) | (1,-5)\n\nIdentify any strictly dominant or dominated strategies for each player.", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy Up: payoffs [-4, -2] against ['Left', 'Right']\n- Strategy Down: payoffs [2, 1] against ['Left', 'Right']\nStrategy Down yields a strictly higher payoff than every other strategy in every column.\nTherefore, Down is a strictly dominant strategy for Player 1. \u2713\nStrategy Up is strictly dominated (another strategy always gives higher payoff). \u2717\n\nPlayer 2's analysis:\n- Strategy Left: payoffs [5, 1] against ['Up', 'Down']\n- Strategy Right: payoffs [3, -5] against ['Up', 'Down']\nStrategy Left yields a strictly higher payoff than every other strategy in every row.\nTherefore, Left is a strictly dominant strategy for Player 2. \u2713\nStrategy Right is strictly dominated. \u2717", | |
| "answer": "{'p1_dominant': [1], 'p2_dominant': [0]}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-mixed-ne-0004", | |
| "category": "normal_form_2x2", | |
| "subcategory": "mixed_nash_equilibrium", | |
| "difficulty": "medium", | |
| "problem": "In the game represented by the payoff matrix below, find every Nash Equilibrium:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (0,4) | (4,0)\nDown | (1,-1) | (-1,5)", | |
| "solution": "There are no pure strategy Nash Equilibria.\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Up with probability 0.6000, Down with probability 0.4000.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.8333, Right with probability 0.1667.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 0.6667, Player 2 gets 2.0000.", | |
| "answer": "[P1=[Up:0.6000, Down:0.4000], P2=[Left:0.8333, Right:0.1667]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-extra-0001", | |
| "category": "normal_form_2x2", | |
| "subcategory": "random_extra", | |
| "difficulty": "easy", | |
| "problem": "Examine the payoff matrix and identify all pure strategy Nash Equilibria:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (4,7) | (-1,1)\nDown | (-4,0) | (1,6)", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Up, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Up, getting payoff 4. If Player 1 switches to Down (while Player 2 stays at Left), payoff drops to -4. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 7. If Player 2 switches to Right (while Player 1 stays at Up), payoff drops to 1. Player 2 has no incentive to deviate. \u2713\nTherefore (Up, Left) is a Nash Equilibrium with payoffs (4,7).\n\nTo verify (Down, Right) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Down, getting payoff 1. If Player 1 switches to Up (while Player 2 stays at Right), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 6. If Player 2 switches to Left (while Player 1 stays at Down), payoff drops to 0. Player 2 has no incentive to deviate. \u2713\nTherefore (Down, Right) is a Nash Equilibrium with payoffs (1,6).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Up with probability 0.5000, Down with probability 0.5000.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.2000, Right with probability 0.8000.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 0.0000, Player 2 gets 3.5000.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Up, Left), (Down, Right), P1=[Up:0.5000, Down:0.5000], P2=[Left:0.2000, Right:0.8000]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "dominant_strategy", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-2x2-dom-strat-0076", | |
| "category": "normal_form_2x2", | |
| "subcategory": "dominant_strategy", | |
| "difficulty": "easy", | |
| "problem": "Analyze the following game for dominant strategies:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | (-3,4) | (-5,-2)\nDown | (1,0) | (0,0)\n\nDoes either player have a dominant strategy? If so, what is it?", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy Up: payoffs [-3, -5] against ['Left', 'Right']\n- Strategy Down: payoffs [1, 0] against ['Left', 'Right']\nStrategy Down yields a strictly higher payoff than every other strategy in every column.\nTherefore, Down is a strictly dominant strategy for Player 1. \u2713\nStrategy Up is strictly dominated (another strategy always gives higher payoff). \u2717\n\nPlayer 2's analysis:\n- Strategy Left: payoffs [4, 0] against ['Up', 'Down']\n- Strategy Right: payoffs [-2, 0] against ['Up', 'Down']\nStrategy Left yields a payoff at least as high as every other strategy in every row.\nTherefore, Left is a weakly dominant strategy for Player 2. \u2713\nStrategy Right is weakly dominated. \u2717", | |
| "answer": "{'p1_dominant': [1], 'p2_dominant': []}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-dom-0009", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_dominant", | |
| "difficulty": "medium", | |
| "problem": "Analyze the following game for dominant strategies:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (-2,5) | (-3,3) | (0,-6)\nMiddle | (-5,-2) | (4,-3) | (6,-2)\nBottom | (1,2) | (2,5) | (6,-4)\n\nDoes either player have a dominant strategy? If so, what is it?", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy Top: payoffs [-2, -3, 0] against ['Left', 'Center', 'Right']\n- Strategy Middle: payoffs [-5, 4, 6] against ['Left', 'Center', 'Right']\n- Strategy Bottom: payoffs [1, 2, 6] against ['Left', 'Center', 'Right']\nNo single strategy dominates all others across every column. Player 1 has no dominant strategy.\nStrategy Top is strictly dominated (another strategy always gives higher payoff). \u2717\n\nPlayer 2's analysis:\n- Strategy Left: payoffs [5, -2, 2] against ['Top', 'Middle', 'Bottom']\n- Strategy Center: payoffs [3, -3, 5] against ['Top', 'Middle', 'Bottom']\n- Strategy Right: payoffs [-6, -2, -4] against ['Top', 'Middle', 'Bottom']\nNo single strategy dominates all others across every row. Player 2 has no dominant strategy.\nStrategy Right is weakly dominated. \u2717", | |
| "answer": "{'p1': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [0], 'weakly_dominated': []}, 'p2': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [], 'weakly_dominated': [2]}}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-mixed-0033", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_mixed_ne", | |
| "difficulty": "medium", | |
| "problem": "Analyze the following 3-by-3 game and determine all Nash Equilibria:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (0,5) | (4,1) | (-4,-5)\nMiddle | (-6,5) | (-1,-6) | (1,-6)\nBottom | (-1,-3) | (-2,-1) | (4,6)", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Top, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 0. If Player 1 switches to Middle (while Player 2 stays at Left), payoff drops to -6. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 0. If Player 1 switches to Bottom (while Player 2 stays at Left), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 5. If Player 2 switches to Center (while Player 1 stays at Top), payoff drops to 1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 5. If Player 2 switches to Right (while Player 1 stays at Top), payoff drops to -5. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, Left) is a Nash Equilibrium with payoffs (0,5).\n\nTo verify (Bottom, Right) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Bottom, getting payoff 4. If Player 1 switches to Top (while Player 2 stays at Right), payoff drops to -4. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Bottom, getting payoff 4. If Player 1 switches to Middle (while Player 2 stays at Right), payoff drops to 1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 6. If Player 2 switches to Left (while Player 1 stays at Bottom), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 6. If Player 2 switches to Center (while Player 1 stays at Bottom), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\nTherefore (Bottom, Right) is a Nash Equilibrium with payoffs (4,6).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.4737, Bottom with probability 0.5263.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.8889, Right with probability 0.1111.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets -0.4444, Player 2 gets 0.7895.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Top, Left), (Bottom, Right), P1=[Top:0.4737, Bottom:0.5263], P2=[Left:0.8889, Right:0.1111]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-iesds-0038", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_iesds", | |
| "difficulty": "medium", | |
| "problem": "Use iterated dominance to simplify the following game:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (-1,4) | (-4,0) | (2,-3)\nMiddle | (2,-1) | (-5,-5) | (-2,2)\nBottom | (3,5) | (-1,0) | (5,-4)\n\nEliminate strictly dominated strategies step by step.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 1's strategies.\n Compare Top vs Bottom: for every column strategy Player 2 might play,\n Bottom gives Player 1 a strictly higher payoff than Top.\n Therefore Top is strictly dominated by Bottom. Eliminate Top. \u2717\n Remaining strategies: P1=['Middle', 'Bottom'], P2=['Left', 'Center', 'Right']\n\nStep 2: Consider Player 1's strategies.\n Compare Middle vs Bottom: for every column strategy Player 2 might play,\n Bottom gives Player 1 a strictly higher payoff than Middle.\n Therefore Middle is strictly dominated by Bottom. Eliminate Middle. \u2717\n Remaining strategies: P1=['Bottom'], P2=['Left', 'Center', 'Right']\n\nStep 3: Consider Player 2's strategies.\n Compare Center vs Left: for every row strategy Player 1 might play,\n Left gives Player 2 a strictly higher payoff than Center.\n Therefore Center is strictly dominated by Left. Eliminate Center. \u2717\n Remaining strategies: P1=['Bottom'], P2=['Left', 'Right']\n\nStep 4: Consider Player 2's strategies.\n Compare Right vs Left: for every row strategy Player 1 might play,\n Left gives Player 2 a strictly higher payoff than Right.\n Therefore Right is strictly dominated by Left. Eliminate Right. \u2717\n Remaining strategies: P1=['Bottom'], P2=['Left']\n\nAfter 4 elimination steps, the unique surviving strategy profile is (Bottom, Left).\nThe resulting payoffs are (3, 5). \u2713", | |
| "answer": "(Bottom, Left)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-multi-0013", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_multi_eq", | |
| "difficulty": "hard", | |
| "problem": "The following 3x3 game has multiple equilibria. Find ALL Nash Equilibria:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (-2,-5) | (0,5) | (1,4)\nMiddle | (-2,4) | (4,-1) | (0,4)\nBottom | (3,4) | (0,-3) | (-3,2)", | |
| "solution": "This game has 3 Nash Equilibria (1 pure, 2 mixed).\n\nThis game has 1 pure strategy Nash Equilibrium.\n\nTo verify (Bottom, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Bottom, getting payoff 3. If Player 1 switches to Top (while Player 2 stays at Left), payoff drops to -2. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Bottom, getting payoff 3. If Player 1 switches to Middle (while Player 2 stays at Left), payoff drops to -2. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 4. If Player 2 switches to Center (while Player 1 stays at Bottom), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 4. If Player 2 switches to Right (while Player 1 stays at Bottom), payoff drops to 2. Player 2 has no incentive to deviate. \u2713\nTherefore (Bottom, Left) is a Nash Equilibrium with payoffs (3,4).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.8333, Middle with probability 0.1667.\nPlayer 2 randomizes over 2 strategies: Center with probability 0.2000, Right with probability 0.8000.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 0.8000, Player 2 gets 4.0000.\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.1818, Bottom with probability 0.8182.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.4444, Right with probability 0.5556.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets -0.3333, Player 2 gets 2.3636.\n\nIn addition to the pure strategy equilibrium, this game has 2 mixed strategy Nash Equilibria.", | |
| "answer": "[(Bottom, Left), P1=[Top:0.8333, Middle:0.1667], P2=[Center:0.2000, Right:0.8000], P1=[Top:0.1818, Bottom:0.8182], P2=[Left:0.4444, Right:0.5556]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "mixed_strategy", | |
| "multiple_equilibria", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-multi-0005", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_multi_eq", | |
| "difficulty": "hard", | |
| "problem": "The following 3x3 game has multiple equilibria. Find ALL Nash Equilibria:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (-3,-1) | (1,2) | (2,2)\nMiddle | (-4,-4) | (-3,0) | (-2,-2)\nBottom | (5,3) | (-1,4) | (-3,-4)", | |
| "solution": "This game has 2 Nash Equilibria (2 pure, 0 mixed).\n\nThis game has 2 pure strategy Nash Equilibria.\n\nTo verify (Top, Center) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 1. If Player 1 switches to Middle (while Player 2 stays at Center), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 1. If Player 1 switches to Bottom (while Player 2 stays at Center), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Center, getting payoff 2. If Player 2 switches to Left (while Player 1 stays at Top), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Center, getting payoff 2. If Player 2 switches to Right (while Player 1 stays at Top), payoff stays at 2. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, Center) is a Nash Equilibrium with payoffs (1,2).\n\nTo verify (Top, Right) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 2. If Player 1 switches to Middle (while Player 2 stays at Right), payoff drops to -2. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 2. If Player 1 switches to Bottom (while Player 2 stays at Right), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 2. If Player 2 switches to Left (while Player 1 stays at Top), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Right, getting payoff 2. If Player 2 switches to Center (while Player 1 stays at Top), payoff stays at 2. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, Right) is a Nash Equilibrium with payoffs (2,2).\n\nThere are no additional mixed strategy equilibria beyond the pure strategy equilibria identified above.", | |
| "answer": "[(Top, Center), (Top, Right)]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "multiple_equilibria", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-multi-0003", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_multi_eq", | |
| "difficulty": "hard", | |
| "problem": "The following 3x3 game has multiple equilibria. Find ALL Nash Equilibria:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (5,-1) | (-5,-3) | (-2,-4)\nMiddle | (4,-3) | (5,3) | (0,-3)\nBottom | (0,-3) | (4,-5) | (0,-4)", | |
| "solution": "This game has 3 Nash Equilibria (2 pure, 1 mixed).\n\nThis game has 2 pure strategy Nash Equilibria.\n\nTo verify (Top, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 5. If Player 1 switches to Middle (while Player 2 stays at Left), payoff drops to 4. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 5. If Player 1 switches to Bottom (while Player 2 stays at Left), payoff drops to 0. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff -1. If Player 2 switches to Center (while Player 1 stays at Top), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff -1. If Player 2 switches to Right (while Player 1 stays at Top), payoff drops to -4. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, Left) is a Nash Equilibrium with payoffs (5,-1).\n\nTo verify (Middle, Center) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Middle, getting payoff 5. If Player 1 switches to Top (while Player 2 stays at Center), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Middle, getting payoff 5. If Player 1 switches to Bottom (while Player 2 stays at Center), payoff drops to 4. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Center, getting payoff 3. If Player 2 switches to Left (while Player 1 stays at Middle), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Center, getting payoff 3. If Player 2 switches to Right (while Player 1 stays at Middle), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\nTherefore (Middle, Center) is a Nash Equilibrium with payoffs (5,3).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.7500, Middle with probability 0.2500.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.9091, Center with probability 0.0909.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 4.0909, Player 2 gets -1.5000.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Top, Left), (Middle, Center), P1=[Top:0.7500, Middle:0.2500], P2=[Left:0.9091, Center:0.0909]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "mixed_strategy", | |
| "multiple_equilibria", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-iesds-0024", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_iesds", | |
| "difficulty": "medium", | |
| "problem": "Apply Iterated Elimination of Strictly Dominated Strategies (IESDS) to the following game:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (0,-2) | (2,0) | (2,2)\nMiddle | (5,0) | (-2,-3) | (-5,3)\nBottom | (1,-3) | (0,-2) | (-1,-1)\n\nShow each elimination step and find the surviving strategy profile.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 2's strategies.\n Compare Left vs Right: for every row strategy Player 1 might play,\n Right gives Player 2 a strictly higher payoff than Left.\n Therefore Left is strictly dominated by Right. Eliminate Left. \u2717\n Remaining strategies: P1=['Top', 'Middle', 'Bottom'], P2=['Center', 'Right']\n\nStep 2: Consider Player 1's strategies.\n Compare Middle vs Top: for every column strategy Player 2 might play,\n Top gives Player 1 a strictly higher payoff than Middle.\n Therefore Middle is strictly dominated by Top. Eliminate Middle. \u2717\n Remaining strategies: P1=['Top', 'Bottom'], P2=['Center', 'Right']\n\nStep 3: Consider Player 1's strategies.\n Compare Bottom vs Top: for every column strategy Player 2 might play,\n Top gives Player 1 a strictly higher payoff than Bottom.\n Therefore Bottom is strictly dominated by Top. Eliminate Bottom. \u2717\n Remaining strategies: P1=['Top'], P2=['Center', 'Right']\n\nStep 4: Consider Player 2's strategies.\n Compare Center vs Right: for every row strategy Player 1 might play,\n Right gives Player 2 a strictly higher payoff than Center.\n Therefore Center is strictly dominated by Right. Eliminate Center. \u2717\n Remaining strategies: P1=['Top'], P2=['Right']\n\nAfter 4 elimination steps, the unique surviving strategy profile is (Top, Right).\nThe resulting payoffs are (2, 2). \u2713", | |
| "answer": "(Top, Right)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-pure-0059", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_pure_ne", | |
| "difficulty": "medium", | |
| "problem": "Consider the following 3x3 strategic form game:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (-1,-8) | (-7,7) | (-1,0)\nMiddle | (4,4) | (4,2) | (-8,4)\nBottom | (-3,1) | (7,-5) | (-1,-3)\n\nFind all Nash Equilibria (pure and mixed).", | |
| "solution": "This game has 1 pure strategy Nash Equilibrium.\n\nTo verify (Middle, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Middle, getting payoff 4. If Player 1 switches to Top (while Player 2 stays at Left), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Middle, getting payoff 4. If Player 1 switches to Bottom (while Player 2 stays at Left), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 4. If Player 2 switches to Center (while Player 1 stays at Middle), payoff drops to 2. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 4. If Player 2 switches to Right (while Player 1 stays at Middle), payoff stays at 4. Player 2 has no incentive to deviate. \u2713\nTherefore (Middle, Left) is a Nash Equilibrium with payoffs (4,4).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 3 strategies: Top with probability 0.2222, Middle with probability 0.3333, Bottom with probability 0.4444.\nPlayer 2 randomizes over 3 strategies: Left with probability 0.4804, Center with probability 0.0686, Right with probability 0.4510.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets -1.4118, Player 2 gets -0.0000.\n\nIn addition to the pure strategy equilibrium, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Middle, Left), P1=[Top:0.2222, Middle:0.3333, Bottom:0.4444], P2=[Left:0.4804, Center:0.0686, Right:0.4510]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-dom-0014", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_dominant", | |
| "difficulty": "medium", | |
| "problem": "Consider the game below:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (3,3) | (4,5) | (-1,0)\nMiddle | (-6,-1) | (-6,-5) | (1,-4)\nBottom | (4,1) | (-1,-3) | (6,6)\n\nIdentify any strictly dominant or dominated strategies for each player.", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy Top: payoffs [3, 4, -1] against ['Left', 'Center', 'Right']\n- Strategy Middle: payoffs [-6, -6, 1] against ['Left', 'Center', 'Right']\n- Strategy Bottom: payoffs [4, -1, 6] against ['Left', 'Center', 'Right']\nNo single strategy dominates all others across every column. Player 1 has no dominant strategy.\nStrategy Middle is strictly dominated (another strategy always gives higher payoff). \u2717\n\nPlayer 2's analysis:\n- Strategy Left: payoffs [3, -1, 1] against ['Top', 'Middle', 'Bottom']\n- Strategy Center: payoffs [5, -5, -3] against ['Top', 'Middle', 'Bottom']\n- Strategy Right: payoffs [0, -4, 6] against ['Top', 'Middle', 'Bottom']\nNo single strategy dominates all others across every row. Player 2 has no dominant strategy.", | |
| "answer": "{'p1': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [1], 'weakly_dominated': []}, 'p2': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [], 'weakly_dominated': []}}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x3-mixed-0015", | |
| "category": "normal_form_3x3", | |
| "subcategory": "3x3_mixed_ne", | |
| "difficulty": "medium", | |
| "problem": "Analyze the following 3-by-3 game and determine all Nash Equilibria:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | (3,3) | (-5,-3) | (2,2)\nMiddle | (2,-1) | (-2,6) | (4,-4)\nBottom | (-6,-1) | (0,6) | (3,3)", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Top, Left) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 3. If Player 1 switches to Middle (while Player 2 stays at Left), payoff drops to 2. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 3. If Player 1 switches to Bottom (while Player 2 stays at Left), payoff drops to -6. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 3. If Player 2 switches to Center (while Player 1 stays at Top), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Left, getting payoff 3. If Player 2 switches to Right (while Player 1 stays at Top), payoff drops to 2. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, Left) is a Nash Equilibrium with payoffs (3,3).\n\nTo verify (Bottom, Center) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Bottom, getting payoff 0. If Player 1 switches to Top (while Player 2 stays at Center), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Bottom, getting payoff 0. If Player 1 switches to Middle (while Player 2 stays at Center), payoff drops to -2. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays Center, getting payoff 6. If Player 2 switches to Left (while Player 1 stays at Bottom), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays Center, getting payoff 6. If Player 2 switches to Right (while Player 1 stays at Bottom), payoff drops to 3. Player 2 has no incentive to deviate. \u2713\nTherefore (Bottom, Center) is a Nash Equilibrium with payoffs (0,6).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.5385, Middle with probability 0.4615.\nPlayer 2 randomizes over 2 strategies: Left with probability 0.7500, Center with probability 0.2500.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 1.0000, Player 2 gets 1.1538.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Top, Left), (Bottom, Center), P1=[Top:0.5385, Middle:0.4615], P2=[Left:0.7500, Center:0.2500]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-iesds-0011", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_iesds", | |
| "difficulty": "medium", | |
| "problem": "Use iterated dominance to simplify the following game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (-1,-2) | (-5,1) | (-4,5) | (5,0)\nMiddle | (-2,3) | (0,-4) | (5,5) | (1,1)\nBottom | (-5,5) | (2,-1) | (-5,1) | (3,-5)\n\nEliminate strictly dominated strategies step by step.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 2's strategies.\n Compare C2 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C3. Eliminate C2. \u2717\n Remaining strategies: P1=['Top', 'Middle', 'Bottom'], P2=['C1', 'C3', 'C4']\n\nStep 2: Consider Player 1's strategies.\n Compare Bottom vs Top: for every column strategy Player 2 might play,\n Top gives Player 1 a strictly higher payoff than Bottom.\n Therefore Bottom is strictly dominated by Top. Eliminate Bottom. \u2717\n Remaining strategies: P1=['Top', 'Middle'], P2=['C1', 'C3', 'C4']\n\nStep 3: Consider Player 2's strategies.\n Compare C1 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C1.\n Therefore C1 is strictly dominated by C3. Eliminate C1. \u2717\n Remaining strategies: P1=['Top', 'Middle'], P2=['C3', 'C4']\n\nStep 4: Consider Player 2's strategies.\n Compare C4 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C3. Eliminate C4. \u2717\n Remaining strategies: P1=['Top', 'Middle'], P2=['C3']\n\nStep 5: Consider Player 1's strategies.\n Compare Top vs Middle: for every column strategy Player 2 might play,\n Middle gives Player 1 a strictly higher payoff than Top.\n Therefore Top is strictly dominated by Middle. Eliminate Top. \u2717\n Remaining strategies: P1=['Middle'], P2=['C3']\n\nAfter 5 elimination steps, the unique surviving strategy profile is (Middle, C3).\nThe resulting payoffs are (5, 5). \u2713", | |
| "answer": "(Middle, C3)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-iesds-0030", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_iesds", | |
| "difficulty": "medium", | |
| "problem": "Use iterated dominance to simplify the following game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (0,-3) | (-5,-4) | (-2,0) | (-2,-1)\nMiddle | (3,2) | (3,-5) | (0,5) | (2,4)\nBottom | (4,-3) | (-2,1) | (4,4) | (2,-2)\n\nEliminate strictly dominated strategies step by step.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 1's strategies.\n Compare Top vs Middle: for every column strategy Player 2 might play,\n Middle gives Player 1 a strictly higher payoff than Top.\n Therefore Top is strictly dominated by Middle. Eliminate Top. \u2717\n Remaining strategies: P1=['Middle', 'Bottom'], P2=['C1', 'C2', 'C3', 'C4']\n\nStep 2: Consider Player 2's strategies.\n Compare C1 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C1.\n Therefore C1 is strictly dominated by C3. Eliminate C1. \u2717\n Remaining strategies: P1=['Middle', 'Bottom'], P2=['C2', 'C3', 'C4']\n\nStep 3: Consider Player 2's strategies.\n Compare C2 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C3. Eliminate C2. \u2717\n Remaining strategies: P1=['Middle', 'Bottom'], P2=['C3', 'C4']\n\nStep 4: Consider Player 2's strategies.\n Compare C4 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C3. Eliminate C4. \u2717\n Remaining strategies: P1=['Middle', 'Bottom'], P2=['C3']\n\nStep 5: Consider Player 1's strategies.\n Compare Middle vs Bottom: for every column strategy Player 2 might play,\n Bottom gives Player 1 a strictly higher payoff than Middle.\n Therefore Middle is strictly dominated by Bottom. Eliminate Middle. \u2717\n Remaining strategies: P1=['Bottom'], P2=['C3']\n\nAfter 5 elimination steps, the unique surviving strategy profile is (Bottom, C3).\nThe resulting payoffs are (4, 4). \u2713", | |
| "answer": "(Bottom, C3)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-iesds-0013", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_iesds", | |
| "difficulty": "medium", | |
| "problem": "In the game below, apply IESDS to find the solution:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (3,-5) | (-5,2) | (2,4) | (3,-5)\nMiddle | (3,-5) | (2,-3) | (-2,2) | (1,2)\nBottom | (-5,1) | (1,-1) | (0,2) | (-1,-4)", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 2's strategies.\n Compare C1 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C1.\n Therefore C1 is strictly dominated by C3. Eliminate C1. \u2717\n Remaining strategies: P1=['Top', 'Middle', 'Bottom'], P2=['C2', 'C3', 'C4']\n\nStep 2: Consider Player 2's strategies.\n Compare C2 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C3. Eliminate C2. \u2717\n Remaining strategies: P1=['Top', 'Middle', 'Bottom'], P2=['C3', 'C4']\n\nStep 3: Consider Player 1's strategies.\n Compare Middle vs Top: for every column strategy Player 2 might play,\n Top gives Player 1 a strictly higher payoff than Middle.\n Therefore Middle is strictly dominated by Top. Eliminate Middle. \u2717\n Remaining strategies: P1=['Top', 'Bottom'], P2=['C3', 'C4']\n\nStep 4: Consider Player 1's strategies.\n Compare Bottom vs Top: for every column strategy Player 2 might play,\n Top gives Player 1 a strictly higher payoff than Bottom.\n Therefore Bottom is strictly dominated by Top. Eliminate Bottom. \u2717\n Remaining strategies: P1=['Top'], P2=['C3', 'C4']\n\nStep 5: Consider Player 2's strategies.\n Compare C4 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C3. Eliminate C4. \u2717\n Remaining strategies: P1=['Top'], P2=['C3']\n\nAfter 5 elimination steps, the unique surviving strategy profile is (Top, C3).\nThe resulting payoffs are (2, 4). \u2713", | |
| "answer": "(Top, C3)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-mixed-0038", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_mixed_ne", | |
| "difficulty": "hard", | |
| "problem": "Analyze the following 3-by-4 game and determine all Nash Equilibria:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (-6,1) | (5,2) | (-1,-3) | (-4,-1)\nMiddle | (4,-2) | (2,-2) | (-2,-3) | (6,-5)\nBottom | (-1,5) | (4,-1) | (2,2) | (2,5)", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Top, C2) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 5. If Player 1 switches to Middle (while Player 2 stays at C2), payoff drops to 2. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 5. If Player 1 switches to Bottom (while Player 2 stays at C2), payoff drops to 4. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 2. If Player 2 switches to C1 (while Player 1 stays at Top), payoff drops to 1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 2. If Player 2 switches to C3 (while Player 1 stays at Top), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 2. If Player 2 switches to C4 (while Player 1 stays at Top), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, C2) is a Nash Equilibrium with payoffs (5,2).\n\nTo verify (Middle, C1) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Middle, getting payoff 4. If Player 1 switches to Top (while Player 2 stays at C1), payoff drops to -6. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Middle, getting payoff 4. If Player 1 switches to Bottom (while Player 2 stays at C1), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff -2. If Player 2 switches to C2 (while Player 1 stays at Middle), payoff stays at -2. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff -2. If Player 2 switches to C3 (while Player 1 stays at Middle), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff -2. If Player 2 switches to C4 (while Player 1 stays at Middle), payoff drops to -5. Player 2 has no incentive to deviate. \u2713\nTherefore (Middle, C1) is a Nash Equilibrium with payoffs (4,-2).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.8571, Bottom with probability 0.1429.\nPlayer 2 randomizes over 2 strategies: C1 with probability 0.1667, C2 with probability 0.8333.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 3.1667, Player 2 gets 1.5714.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Top, C2), (Middle, C1), P1=[Top:0.8571, Bottom:0.1429], P2=[C1:0.1667, C2:0.8333]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-mixed-0012", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_mixed_ne", | |
| "difficulty": "hard", | |
| "problem": "Consider the following 3x4 strategic form game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (-5,-1) | (0,2) | (3,3) | (3,6)\nMiddle | (-5,4) | (-6,5) | (-2,-6) | (5,-2)\nBottom | (6,2) | (-6,2) | (-6,-6) | (-6,1)\n\nFind all Nash Equilibria (pure and mixed).", | |
| "solution": "This game has 1 pure strategy Nash Equilibrium.\n\nTo verify (Bottom, C1) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Bottom, getting payoff 6. If Player 1 switches to Top (while Player 2 stays at C1), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Bottom, getting payoff 6. If Player 1 switches to Middle (while Player 2 stays at C1), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 2. If Player 2 switches to C2 (while Player 1 stays at Bottom), payoff stays at 2. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 2. If Player 2 switches to C3 (while Player 1 stays at Bottom), payoff drops to -6. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 2. If Player 2 switches to C4 (while Player 1 stays at Bottom), payoff drops to 1. Player 2 has no incentive to deviate. \u2713\nTherefore (Bottom, C1) is a Nash Equilibrium with payoffs (6,2).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.6364, Middle with probability 0.3636.\nPlayer 2 randomizes over 2 strategies: C2 with probability 0.2500, C4 with probability 0.7500.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 2.2500, Player 2 gets 3.0909.\n\nIn addition to the pure strategy equilibrium, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Bottom, C1), P1=[Top:0.6364, Middle:0.3636], P2=[C2:0.2500, C4:0.7500]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-multi-0007", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_multi_eq", | |
| "difficulty": "hard", | |
| "problem": "The following 3x4 game has multiple equilibria. Find ALL Nash Equilibria:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (-3,5) | (2,3) | (4,0) | (-5,2)\nMiddle | (-5,3) | (4,3) | (2,2) | (3,4)\nBottom | (4,2) | (0,-3) | (-1,-3) | (-4,-4)", | |
| "solution": "This game has 2 Nash Equilibria (2 pure, 0 mixed).\n\nThis game has 2 pure strategy Nash Equilibria.\n\nTo verify (Middle, C4) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Middle, getting payoff 3. If Player 1 switches to Top (while Player 2 stays at C4), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Middle, getting payoff 3. If Player 1 switches to Bottom (while Player 2 stays at C4), payoff drops to -4. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 4. If Player 2 switches to C1 (while Player 1 stays at Middle), payoff drops to 3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 4. If Player 2 switches to C2 (while Player 1 stays at Middle), payoff drops to 3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 4. If Player 2 switches to C3 (while Player 1 stays at Middle), payoff drops to 2. Player 2 has no incentive to deviate. \u2713\nTherefore (Middle, C4) is a Nash Equilibrium with payoffs (3,4).\n\nTo verify (Bottom, C1) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Bottom, getting payoff 4. If Player 1 switches to Top (while Player 2 stays at C1), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Bottom, getting payoff 4. If Player 1 switches to Middle (while Player 2 stays at C1), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 2. If Player 2 switches to C2 (while Player 1 stays at Bottom), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 2. If Player 2 switches to C3 (while Player 1 stays at Bottom), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 2. If Player 2 switches to C4 (while Player 1 stays at Bottom), payoff drops to -4. Player 2 has no incentive to deviate. \u2713\nTherefore (Bottom, C1) is a Nash Equilibrium with payoffs (4,2).\n\nThere are no additional mixed strategy equilibria beyond the pure strategy equilibria identified above.", | |
| "answer": "[(Middle, C4), (Bottom, C1)]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "multiple_equilibria", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-iesds-0018", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_iesds", | |
| "difficulty": "medium", | |
| "problem": "Apply Iterated Elimination of Strictly Dominated Strategies (IESDS) to the following game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (-2,2) | (-5,5) | (-5,-2) | (-5,1)\nMiddle | (1,-2) | (-5,-5) | (0,0) | (-4,-1)\nBottom | (0,3) | (0,3) | (5,5) | (-3,2)\n\nShow each elimination step and find the surviving strategy profile.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 1's strategies.\n Compare Top vs Bottom: for every column strategy Player 2 might play,\n Bottom gives Player 1 a strictly higher payoff than Top.\n Therefore Top is strictly dominated by Bottom. Eliminate Top. \u2717\n Remaining strategies: P1=['Middle', 'Bottom'], P2=['C1', 'C2', 'C3', 'C4']\n\nStep 2: Consider Player 2's strategies.\n Compare C1 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C1.\n Therefore C1 is strictly dominated by C3. Eliminate C1. \u2717\n Remaining strategies: P1=['Middle', 'Bottom'], P2=['C2', 'C3', 'C4']\n\nStep 3: Consider Player 1's strategies.\n Compare Middle vs Bottom: for every column strategy Player 2 might play,\n Bottom gives Player 1 a strictly higher payoff than Middle.\n Therefore Middle is strictly dominated by Bottom. Eliminate Middle. \u2717\n Remaining strategies: P1=['Bottom'], P2=['C2', 'C3', 'C4']\n\nStep 4: Consider Player 2's strategies.\n Compare C2 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C3. Eliminate C2. \u2717\n Remaining strategies: P1=['Bottom'], P2=['C3', 'C4']\n\nStep 5: Consider Player 2's strategies.\n Compare C4 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C3. Eliminate C4. \u2717\n Remaining strategies: P1=['Bottom'], P2=['C3']\n\nAfter 5 elimination steps, the unique surviving strategy profile is (Bottom, C3).\nThe resulting payoffs are (5, 5). \u2713", | |
| "answer": "(Bottom, C3)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-dom-0030", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_dominant", | |
| "difficulty": "medium", | |
| "problem": "Analyze the following game for dominant strategies:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (4,2) | (2,5) | (1,-3) | (6,-3)\nMiddle | (3,-2) | (-1,1) | (4,4) | (3,-2)\nBottom | (4,-3) | (3,1) | (-6,4) | (0,-2)\n\nDoes either player have a dominant strategy? If so, what is it?", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy Top: payoffs [4, 2, 1, 6] against ['C1', 'C2', 'C3', 'C4']\n- Strategy Middle: payoffs [3, -1, 4, 3] against ['C1', 'C2', 'C3', 'C4']\n- Strategy Bottom: payoffs [4, 3, -6, 0] against ['C1', 'C2', 'C3', 'C4']\nNo single strategy dominates all others across every column. Player 1 has no dominant strategy.\n\nPlayer 2's analysis:\n- Strategy C1: payoffs [2, -2, -3] against ['Top', 'Middle', 'Bottom']\n- Strategy C2: payoffs [5, 1, 1] against ['Top', 'Middle', 'Bottom']\n- Strategy C3: payoffs [-3, 4, 4] against ['Top', 'Middle', 'Bottom']\n- Strategy C4: payoffs [-3, -2, -2] against ['Top', 'Middle', 'Bottom']\nNo single strategy dominates all others across every row. Player 2 has no dominant strategy.\nStrategy C1 is strictly dominated. \u2717\nStrategy C4 is strictly dominated. \u2717", | |
| "answer": "{'p1': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [], 'weakly_dominated': []}, 'p2': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [0, 3], 'weakly_dominated': []}}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-mixed-0035", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_mixed_ne", | |
| "difficulty": "hard", | |
| "problem": "Players 1 and 2 play the following 3x4 simultaneous game. Find all equilibria:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (5,6) | (-1,1) | (-6,4) | (-5,-1)\nMiddle | (-2,4) | (-5,-4) | (3,-6) | (-6,-5)\nBottom | (-1,-2) | (1,6) | (1,3) | (6,-2)", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Top, C1) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 5. If Player 1 switches to Middle (while Player 2 stays at C1), payoff drops to -2. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 5. If Player 1 switches to Bottom (while Player 2 stays at C1), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 6. If Player 2 switches to C2 (while Player 1 stays at Top), payoff drops to 1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 6. If Player 2 switches to C3 (while Player 1 stays at Top), payoff drops to 4. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 6. If Player 2 switches to C4 (while Player 1 stays at Top), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, C1) is a Nash Equilibrium with payoffs (5,6).\n\nTo verify (Bottom, C2) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Bottom, getting payoff 1. If Player 1 switches to Top (while Player 2 stays at C2), payoff drops to -1. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Bottom, getting payoff 1. If Player 1 switches to Middle (while Player 2 stays at C2), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 6. If Player 2 switches to C1 (while Player 1 stays at Bottom), payoff drops to -2. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 6. If Player 2 switches to C3 (while Player 1 stays at Bottom), payoff drops to 3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 6. If Player 2 switches to C4 (while Player 1 stays at Bottom), payoff drops to -2. Player 2 has no incentive to deviate. \u2713\nTherefore (Bottom, C2) is a Nash Equilibrium with payoffs (1,6).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 3 strategies: Top with probability 0.4819, Middle with probability 0.1084, Bottom with probability 0.4096.\nPlayer 2 randomizes over 3 strategies: C1 with probability 0.5169, C2 with probability 0.0562, C3 with probability 0.4270.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets -0.0337, Player 2 gets 2.5060.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Top, C1), (Bottom, C2), P1=[Top:0.4819, Middle:0.1084, Bottom:0.4096], P2=[C1:0.5169, C2:0.0562, C3:0.4270]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-3x4-pure-0042", | |
| "category": "normal_form_3x4", | |
| "subcategory": "3x4_pure_ne", | |
| "difficulty": "hard", | |
| "problem": "Players 1 and 2 play the following 3x4 simultaneous game. Find all equilibria:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | (4,-7) | (1,8) | (5,0) | (0,3)\nMiddle | (-2,-6) | (-6,2) | (-3,-8) | (-7,4)\nBottom | (-3,6) | (-6,-4) | (7,8) | (-1,-3)", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (Top, C2) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Top, getting payoff 1. If Player 1 switches to Middle (while Player 2 stays at C2), payoff drops to -6. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Top, getting payoff 1. If Player 1 switches to Bottom (while Player 2 stays at C2), payoff drops to -6. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 8. If Player 2 switches to C1 (while Player 1 stays at Top), payoff drops to -7. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 8. If Player 2 switches to C3 (while Player 1 stays at Top), payoff drops to 0. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C2, getting payoff 8. If Player 2 switches to C4 (while Player 1 stays at Top), payoff drops to 3. Player 2 has no incentive to deviate. \u2713\nTherefore (Top, C2) is a Nash Equilibrium with payoffs (1,8).\n\nTo verify (Bottom, C3) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays Bottom, getting payoff 7. If Player 1 switches to Top (while Player 2 stays at C3), payoff drops to 5. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays Bottom, getting payoff 7. If Player 1 switches to Middle (while Player 2 stays at C3), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C3, getting payoff 8. If Player 2 switches to C1 (while Player 1 stays at Bottom), payoff drops to 6. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C3, getting payoff 8. If Player 2 switches to C2 (while Player 1 stays at Bottom), payoff drops to -4. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C3, getting payoff 8. If Player 2 switches to C4 (while Player 1 stays at Bottom), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\nTherefore (Bottom, C3) is a Nash Equilibrium with payoffs (7,8).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 2 strategies: Top with probability 0.6000, Bottom with probability 0.4000.\nPlayer 2 randomizes over 2 strategies: C2 with probability 0.2222, C3 with probability 0.7778.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 4.1111, Player 2 gets 3.2000.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(Top, C2), (Bottom, C3), P1=[Top:0.6000, Bottom:0.4000], P2=[C2:0.2222, C3:0.7778]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-dom-0012", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_dominant", | |
| "difficulty": "medium", | |
| "problem": "For each player in the following game, determine if they have a dominant strategy:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (-1,3) | (-5,3) | (-4,1) | (-4,-5)\nR2 | (-3,6) | (-6,-6) | (6,-1) | (-1,-5)\nR3 | (4,4) | (-1,1) | (-3,6) | (1,-2)\nR4 | (-2,-5) | (3,4) | (-3,5) | (0,-2)", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy R1: payoffs [-1, -5, -4, -4] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R2: payoffs [-3, -6, 6, -1] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R3: payoffs [4, -1, -3, 1] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R4: payoffs [-2, 3, -3, 0] against ['C1', 'C2', 'C3', 'C4']\nNo single strategy dominates all others across every column. Player 1 has no dominant strategy.\nStrategy R1 is strictly dominated (another strategy always gives higher payoff). \u2717\n\nPlayer 2's analysis:\n- Strategy C1: payoffs [3, 6, 4, -5] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C2: payoffs [3, -6, 1, 4] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C3: payoffs [1, -1, 6, 5] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C4: payoffs [-5, -5, -2, -2] against ['R1', 'R2', 'R3', 'R4']\nNo single strategy dominates all others across every row. Player 2 has no dominant strategy.\nStrategy C4 is strictly dominated. \u2717", | |
| "answer": "{'p1': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [0], 'weakly_dominated': []}, 'p2': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [3], 'weakly_dominated': []}}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-dom-0007", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_dominant", | |
| "difficulty": "medium", | |
| "problem": "Consider the game below:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (0,1) | (0,5) | (2,-2) | (-6,-3)\nR2 | (1,-2) | (5,-2) | (6,6) | (4,3)\nR3 | (1,-4) | (0,-3) | (5,-3) | (-1,1)\nR4 | (-6,-2) | (4,-1) | (3,3) | (4,-5)\n\nIdentify any strictly dominant or dominated strategies for each player.", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy R1: payoffs [0, 0, 2, -6] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R2: payoffs [1, 5, 6, 4] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R3: payoffs [1, 0, 5, -1] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R4: payoffs [-6, 4, 3, 4] against ['C1', 'C2', 'C3', 'C4']\nStrategy R2 yields a payoff at least as high as every other strategy in every column (and strictly higher in at least one).\nTherefore, R2 is a weakly dominant strategy for Player 1. \u2713\nStrategy R1 is strictly dominated (another strategy always gives higher payoff). \u2717\nStrategy R3 is weakly dominated. \u2717\nStrategy R4 is weakly dominated. \u2717\n\nPlayer 2's analysis:\n- Strategy C1: payoffs [1, -2, -4, -2] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C2: payoffs [5, -2, -3, -1] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C3: payoffs [-2, 6, -3, 3] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C4: payoffs [-3, 3, 1, -5] against ['R1', 'R2', 'R3', 'R4']\nNo single strategy dominates all others across every row. Player 2 has no dominant strategy.\nStrategy C1 is weakly dominated. \u2717", | |
| "answer": "{'p1': {'strictly_dominant': [], 'weakly_dominant': [1], 'strictly_dominated': [0], 'weakly_dominated': [2, 3]}, 'p2': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [], 'weakly_dominated': [0]}}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-dom-0022", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_dominant", | |
| "difficulty": "medium", | |
| "problem": "Consider the game below:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (2,-4) | (-4,-6) | (-3,-6) | (3,-2)\nR2 | (-2,3) | (0,3) | (-2,-5) | (2,-5)\nR3 | (-1,5) | (-4,-3) | (-1,3) | (-1,4)\nR4 | (5,5) | (3,5) | (-6,0) | (0,1)\n\nIdentify any strictly dominant or dominated strategies for each player.", | |
| "solution": "To identify dominant strategies, we compare each player's payoffs across all opponent strategies:\n\nPlayer 1's analysis:\n- Strategy R1: payoffs [2, -4, -3, 3] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R2: payoffs [-2, 0, -2, 2] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R3: payoffs [-1, -4, -1, -1] against ['C1', 'C2', 'C3', 'C4']\n- Strategy R4: payoffs [5, 3, -6, 0] against ['C1', 'C2', 'C3', 'C4']\nNo single strategy dominates all others across every column. Player 1 has no dominant strategy.\n\nPlayer 2's analysis:\n- Strategy C1: payoffs [-4, 3, 5, 5] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C2: payoffs [-6, 3, -3, 5] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C3: payoffs [-6, -5, 3, 0] against ['R1', 'R2', 'R3', 'R4']\n- Strategy C4: payoffs [-2, -5, 4, 1] against ['R1', 'R2', 'R3', 'R4']\nNo single strategy dominates all others across every row. Player 2 has no dominant strategy.\nStrategy C3 is strictly dominated. \u2717\nStrategy C2 is weakly dominated. \u2717", | |
| "answer": "{'p1': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [], 'weakly_dominated': []}, 'p2': {'strictly_dominant': [], 'weakly_dominant': [], 'strictly_dominated': [2], 'weakly_dominated': [1]}}", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominant_strategy", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-mixed-0009", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_mixed_ne", | |
| "difficulty": "hard", | |
| "problem": "Consider the following 4x4 strategic form game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (-1,-6) | (-6,1) | (0,4) | (4,6)\nR2 | (-3,4) | (-2,-3) | (-1,-5) | (4,4)\nR3 | (-6,-1) | (2,-5) | (3,-2) | (-3,-5)\nR4 | (1,-4) | (-2,4) | (4,-1) | (1,-6)\n\nFind all Nash Equilibria (pure and mixed).", | |
| "solution": "This game has 2 pure strategy Nash Equilibria.\n\nTo verify (R1, C4) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays R1, getting payoff 4. If Player 1 switches to R2 (while Player 2 stays at C4), payoff stays at 4. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays R1, getting payoff 4. If Player 1 switches to R3 (while Player 2 stays at C4), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays R1, getting payoff 4. If Player 1 switches to R4 (while Player 2 stays at C4), payoff drops to 1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 6. If Player 2 switches to C1 (while Player 1 stays at R1), payoff drops to -6. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 6. If Player 2 switches to C2 (while Player 1 stays at R1), payoff drops to 1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 6. If Player 2 switches to C3 (while Player 1 stays at R1), payoff drops to 4. Player 2 has no incentive to deviate. \u2713\nTherefore (R1, C4) is a Nash Equilibrium with payoffs (4,6).\n\nTo verify (R2, C4) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays R2, getting payoff 4. If Player 1 switches to R1 (while Player 2 stays at C4), payoff stays at 4. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays R2, getting payoff 4. If Player 1 switches to R3 (while Player 2 stays at C4), payoff drops to -3. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays R2, getting payoff 4. If Player 1 switches to R4 (while Player 2 stays at C4), payoff drops to 1. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 4. If Player 2 switches to C1 (while Player 1 stays at R2), payoff stays at 4. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 4. If Player 2 switches to C2 (while Player 1 stays at R2), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C4, getting payoff 4. If Player 2 switches to C3 (while Player 1 stays at R2), payoff drops to -5. Player 2 has no incentive to deviate. \u2713\nTherefore (R2, C4) is a Nash Equilibrium with payoffs (4,4).\n\nMixed Strategy Nash Equilibrium:\nPlayer 1 randomizes over 3 strategies: R1 with probability 0.0673, R2 with probability 0.5288, R4 with probability 0.4038.\nPlayer 2 randomizes over 3 strategies: C1 with probability 0.3529, C2 with probability 0.1765, C4 with probability 0.4706.\nIn this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.\nExpected payoffs: Player 1 gets 0.4706, Player 2 gets 0.0962.\n\nIn addition to the pure strategy equilibria, this game has 1 mixed strategy Nash Equilibrium.", | |
| "answer": "[(R1, C4), (R2, C4), P1=[R1:0.0673, R2:0.5288, R4:0.4038], P2=[C1:0.3529, C2:0.1765, C4:0.4706]]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "mixed_strategy", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-iesds-0030", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_iesds", | |
| "difficulty": "hard", | |
| "problem": "Apply Iterated Elimination of Strictly Dominated Strategies (IESDS) to the following game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (-3,0) | (1,1) | (3,3) | (-5,0)\nR2 | (0,4) | (5,-5) | (-4,2) | (-1,-4)\nR3 | (1,-3) | (1,-1) | (4,0) | (1,1)\nR4 | (-2,-2) | (0,-3) | (5,3) | (4,-2)\n\nShow each elimination step and find the surviving strategy profile.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 2's strategies.\n Compare C2 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C3. Eliminate C2. \u2717\n Remaining strategies: P1=['R1', 'R2', 'R3', 'R4'], P2=['C1', 'C3', 'C4']\n\nStep 2: Consider Player 1's strategies.\n Compare R1 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R1.\n Therefore R1 is strictly dominated by R3. Eliminate R1. \u2717\n Remaining strategies: P1=['R2', 'R3', 'R4'], P2=['C1', 'C3', 'C4']\n\nStep 3: Consider Player 1's strategies.\n Compare R2 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R2.\n Therefore R2 is strictly dominated by R3. Eliminate R2. \u2717\n Remaining strategies: P1=['R3', 'R4'], P2=['C1', 'C3', 'C4']\n\nStep 4: Consider Player 2's strategies.\n Compare C1 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C1.\n Therefore C1 is strictly dominated by C3. Eliminate C1. \u2717\n Remaining strategies: P1=['R3', 'R4'], P2=['C3', 'C4']\n\nStep 5: Consider Player 1's strategies.\n Compare R3 vs R4: for every column strategy Player 2 might play,\n R4 gives Player 1 a strictly higher payoff than R3.\n Therefore R3 is strictly dominated by R4. Eliminate R3. \u2717\n Remaining strategies: P1=['R4'], P2=['C3', 'C4']\n\nStep 6: Consider Player 2's strategies.\n Compare C4 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C3. Eliminate C4. \u2717\n Remaining strategies: P1=['R4'], P2=['C3']\n\nAfter 6 elimination steps, the unique surviving strategy profile is (R4, C3).\nThe resulting payoffs are (5, 3). \u2713", | |
| "answer": "(R4, C3)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-iesds-0025", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_iesds", | |
| "difficulty": "hard", | |
| "problem": "Use iterated dominance to simplify the following game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (1,0) | (1,-3) | (4,-1) | (-4,-4)\nR2 | (1,-2) | (-3,5) | (2,-3) | (2,-4)\nR3 | (3,0) | (5,5) | (-2,-3) | (4,-2)\nR4 | (-3,0) | (3,-1) | (3,-2) | (-4,-2)\n\nEliminate strictly dominated strategies step by step.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 2's strategies.\n Compare C3 vs C1: for every row strategy Player 1 might play,\n C1 gives Player 2 a strictly higher payoff than C3.\n Therefore C3 is strictly dominated by C1. Eliminate C3. \u2717\n Remaining strategies: P1=['R1', 'R2', 'R3', 'R4'], P2=['C1', 'C2', 'C4']\n\nStep 2: Consider Player 1's strategies.\n Compare R1 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R1.\n Therefore R1 is strictly dominated by R3. Eliminate R1. \u2717\n Remaining strategies: P1=['R2', 'R3', 'R4'], P2=['C1', 'C2', 'C4']\n\nStep 3: Consider Player 1's strategies.\n Compare R2 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R2.\n Therefore R2 is strictly dominated by R3. Eliminate R2. \u2717\n Remaining strategies: P1=['R3', 'R4'], P2=['C1', 'C2', 'C4']\n\nStep 4: Consider Player 1's strategies.\n Compare R4 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R4.\n Therefore R4 is strictly dominated by R3. Eliminate R4. \u2717\n Remaining strategies: P1=['R3'], P2=['C1', 'C2', 'C4']\n\nStep 5: Consider Player 2's strategies.\n Compare C1 vs C2: for every row strategy Player 1 might play,\n C2 gives Player 2 a strictly higher payoff than C1.\n Therefore C1 is strictly dominated by C2. Eliminate C1. \u2717\n Remaining strategies: P1=['R3'], P2=['C2', 'C4']\n\nStep 6: Consider Player 2's strategies.\n Compare C4 vs C2: for every row strategy Player 1 might play,\n C2 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C2. Eliminate C4. \u2717\n Remaining strategies: P1=['R3'], P2=['C2']\n\nAfter 6 elimination steps, the unique surviving strategy profile is (R3, C2).\nThe resulting payoffs are (5, 5). \u2713", | |
| "answer": "(R3, C2)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-iesds-0017", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_iesds", | |
| "difficulty": "hard", | |
| "problem": "Use iterated dominance to simplify the following game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (-5,5) | (3,4) | (-1,3) | (1,-3)\nR2 | (0,-3) | (-2,0) | (-5,-3) | (-2,3)\nR3 | (4,5) | (4,2) | (2,-2) | (5,0)\nR4 | (-5,2) | (-4,-2) | (2,-1) | (-4,1)\n\nEliminate strictly dominated strategies step by step.", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 1's strategies.\n Compare R1 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R1.\n Therefore R1 is strictly dominated by R3. Eliminate R1. \u2717\n Remaining strategies: P1=['R2', 'R3', 'R4'], P2=['C1', 'C2', 'C3', 'C4']\n\nStep 2: Consider Player 1's strategies.\n Compare R2 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R2.\n Therefore R2 is strictly dominated by R3. Eliminate R2. \u2717\n Remaining strategies: P1=['R3', 'R4'], P2=['C1', 'C2', 'C3', 'C4']\n\nStep 3: Consider Player 2's strategies.\n Compare C2 vs C1: for every row strategy Player 1 might play,\n C1 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C1. Eliminate C2. \u2717\n Remaining strategies: P1=['R3', 'R4'], P2=['C1', 'C3', 'C4']\n\nStep 4: Consider Player 2's strategies.\n Compare C3 vs C1: for every row strategy Player 1 might play,\n C1 gives Player 2 a strictly higher payoff than C3.\n Therefore C3 is strictly dominated by C1. Eliminate C3. \u2717\n Remaining strategies: P1=['R3', 'R4'], P2=['C1', 'C4']\n\nStep 5: Consider Player 1's strategies.\n Compare R4 vs R3: for every column strategy Player 2 might play,\n R3 gives Player 1 a strictly higher payoff than R4.\n Therefore R4 is strictly dominated by R3. Eliminate R4. \u2717\n Remaining strategies: P1=['R3'], P2=['C1', 'C4']\n\nStep 6: Consider Player 2's strategies.\n Compare C4 vs C1: for every row strategy Player 1 might play,\n C1 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C1. Eliminate C4. \u2717\n Remaining strategies: P1=['R3'], P2=['C1']\n\nAfter 6 elimination steps, the unique surviving strategy profile is (R3, C1).\nThe resulting payoffs are (4, 5). \u2713", | |
| "answer": "(R3, C1)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-pure-0019", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_pure_ne", | |
| "difficulty": "hard", | |
| "problem": "Consider the following 4x4 strategic form game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (3,4) | (3,5) | (-3,-5) | (-2,-2)\nR2 | (-6,-1) | (7,4) | (7,-3) | (-2,-3)\nR3 | (-5,-6) | (-1,-6) | (4,4) | (4,-7)\nR4 | (8,7) | (8,-3) | (-4,-1) | (-3,-1)\n\nFind all Nash Equilibria (pure and mixed).", | |
| "solution": "This game has 1 pure strategy Nash Equilibrium.\n\nTo verify (R4, C1) is a Nash Equilibrium, we check each player's incentive to deviate:\n- Player 1 currently plays R4, getting payoff 8. If Player 1 switches to R1 (while Player 2 stays at C1), payoff drops to 3. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays R4, getting payoff 8. If Player 1 switches to R2 (while Player 2 stays at C1), payoff drops to -6. Player 1 has no incentive to deviate. \u2713\n- Player 1 currently plays R4, getting payoff 8. If Player 1 switches to R3 (while Player 2 stays at C1), payoff drops to -5. Player 1 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 7. If Player 2 switches to C2 (while Player 1 stays at R4), payoff drops to -3. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 7. If Player 2 switches to C3 (while Player 1 stays at R4), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\n- Player 2 currently plays C1, getting payoff 7. If Player 2 switches to C4 (while Player 1 stays at R4), payoff drops to -1. Player 2 has no incentive to deviate. \u2713\nTherefore (R4, C1) is a Nash Equilibrium with payoffs (8,7).\n\nThere are no additional mixed strategy equilibria beyond the pure strategy equilibrium identified above.", | |
| "answer": "[(R4, C1)]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "nash_equilibrium", | |
| "normal_form", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-iesds-0007", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_iesds", | |
| "difficulty": "hard", | |
| "problem": "In the game below, apply IESDS to find the solution:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (-1,5) | (3,-1) | (-1,-3) | (1,4)\nR2 | (-5,-4) | (3,-5) | (-5,-4) | (-2,-2)\nR3 | (1,0) | (5,-1) | (3,-2) | (-5,2)\nR4 | (5,1) | (0,-2) | (5,4) | (4,-1)", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 2's strategies.\n Compare C2 vs C1: for every row strategy Player 1 might play,\n C1 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C1. Eliminate C2. \u2717\n Remaining strategies: P1=['R1', 'R2', 'R3', 'R4'], P2=['C1', 'C3', 'C4']\n\nStep 2: Consider Player 1's strategies.\n Compare R1 vs R4: for every column strategy Player 2 might play,\n R4 gives Player 1 a strictly higher payoff than R1.\n Therefore R1 is strictly dominated by R4. Eliminate R1. \u2717\n Remaining strategies: P1=['R2', 'R3', 'R4'], P2=['C1', 'C3', 'C4']\n\nStep 3: Consider Player 1's strategies.\n Compare R2 vs R4: for every column strategy Player 2 might play,\n R4 gives Player 1 a strictly higher payoff than R2.\n Therefore R2 is strictly dominated by R4. Eliminate R2. \u2717\n Remaining strategies: P1=['R3', 'R4'], P2=['C1', 'C3', 'C4']\n\nStep 4: Consider Player 1's strategies.\n Compare R3 vs R4: for every column strategy Player 2 might play,\n R4 gives Player 1 a strictly higher payoff than R3.\n Therefore R3 is strictly dominated by R4. Eliminate R3. \u2717\n Remaining strategies: P1=['R4'], P2=['C1', 'C3', 'C4']\n\nStep 5: Consider Player 2's strategies.\n Compare C1 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C1.\n Therefore C1 is strictly dominated by C3. Eliminate C1. \u2717\n Remaining strategies: P1=['R4'], P2=['C3', 'C4']\n\nStep 6: Consider Player 2's strategies.\n Compare C4 vs C3: for every row strategy Player 1 might play,\n C3 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C3. Eliminate C4. \u2717\n Remaining strategies: P1=['R4'], P2=['C3']\n\nAfter 6 elimination steps, the unique surviving strategy profile is (R4, C3).\nThe resulting payoffs are (5, 4). \u2713", | |
| "answer": "(R4, C3)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-nxm-4x4-iesds-0014", | |
| "category": "normal_form_4x4", | |
| "subcategory": "4x4_iesds", | |
| "difficulty": "hard", | |
| "problem": "In the game below, apply IESDS to find the solution:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nR1 | (2,0) | (-5,0) | (-3,-3) | (-5,-4)\nR2 | (4,3) | (3,2) | (1,-2) | (2,0)\nR3 | (3,-3) | (-3,5) | (4,2) | (5,-3)\nR4 | (-4,-4) | (0,1) | (-1,-3) | (-2,3)", | |
| "solution": "Applying Iterated Elimination of Strictly Dominated Strategies (IESDS):\n\nStep 1: Consider Player 1's strategies.\n Compare R1 vs R2: for every column strategy Player 2 might play,\n R2 gives Player 1 a strictly higher payoff than R1.\n Therefore R1 is strictly dominated by R2. Eliminate R1. \u2717\n Remaining strategies: P1=['R2', 'R3', 'R4'], P2=['C1', 'C2', 'C3', 'C4']\n\nStep 2: Consider Player 1's strategies.\n Compare R4 vs R2: for every column strategy Player 2 might play,\n R2 gives Player 1 a strictly higher payoff than R4.\n Therefore R4 is strictly dominated by R2. Eliminate R4. \u2717\n Remaining strategies: P1=['R2', 'R3'], P2=['C1', 'C2', 'C3', 'C4']\n\nStep 3: Consider Player 2's strategies.\n Compare C3 vs C2: for every row strategy Player 1 might play,\n C2 gives Player 2 a strictly higher payoff than C3.\n Therefore C3 is strictly dominated by C2. Eliminate C3. \u2717\n Remaining strategies: P1=['R2', 'R3'], P2=['C1', 'C2', 'C4']\n\nStep 4: Consider Player 2's strategies.\n Compare C4 vs C2: for every row strategy Player 1 might play,\n C2 gives Player 2 a strictly higher payoff than C4.\n Therefore C4 is strictly dominated by C2. Eliminate C4. \u2717\n Remaining strategies: P1=['R2', 'R3'], P2=['C1', 'C2']\n\nStep 5: Consider Player 1's strategies.\n Compare R3 vs R2: for every column strategy Player 2 might play,\n R2 gives Player 1 a strictly higher payoff than R3.\n Therefore R3 is strictly dominated by R2. Eliminate R3. \u2717\n Remaining strategies: P1=['R2'], P2=['C1', 'C2']\n\nStep 6: Consider Player 2's strategies.\n Compare C2 vs C1: for every row strategy Player 1 might play,\n C1 gives Player 2 a strictly higher payoff than C2.\n Therefore C2 is strictly dominated by C1. Eliminate C2. \u2717\n Remaining strategies: P1=['R2'], P2=['C1']\n\nAfter 6 elimination steps, the unique surviving strategy profile is (R2, C1).\nThe resulting payoffs are (4, 3). \u2713", | |
| "answer": "(R2, C1)", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "4x4", | |
| "dominated_strategy", | |
| "iesds", | |
| "normal_form" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-ultim-0010", | |
| "category": "sequential_game", | |
| "subcategory": "ultimatum_bargaining", | |
| "difficulty": "easy", | |
| "problem": "Analyze this ultimatum bargaining game using backward induction:\n\nA Proposer and a Responder divide $12.\nThe Proposer offers the Responder an amount from: {$0, $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12}.\nThe Proposer keeps the remainder.\nThe Responder can Accept or Reject.\n- If Accepted: Proposer gets $12 minus offer, Responder gets the offer.\n- If Rejected: both get $0.\n\nWhat offer does the proposer make in the SPE?", | |
| "solution": "Solving by backward induction:\n\n**Stage 2 (Responder's decision):**\n- For any offer x \u2265 $0: Accept gives Responder $x, Reject gives $0.\n- Responder accepts any offer \u2265 $0 (weakly dominant). \u2713\n\n**Stage 1 (Proposer's decision):**\n- Proposer knows Responder will accept any offer.\n- Proposer maximizes own payoff: $12 - offer.\n- Optimal offer: $0 (Proposer keeps $12). \u2713\n\n**Subgame Perfect Equilibrium:**\n- Proposer offers $0\n- Responder accepts (any offer \u2265 $0)\n- Payoffs: Proposer=$12, Responder=$0\n\n**Note:** The SPE prediction contrasts with experimental evidence where offers around 40-50% are common and low offers are frequently rejected, showing bounded rationality and fairness concerns.", | |
| "answer": "SPE: Offer=$0, Proposer gets $12, Responder gets $0", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "ultimatum", | |
| "bargaining", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-ultim-0057", | |
| "category": "sequential_game", | |
| "subcategory": "ultimatum_bargaining", | |
| "difficulty": "easy", | |
| "problem": "In this bargaining game, the proposer makes a take-it-or-leave-it offer:\n\nA Proposer and a Responder divide $100.\nThe Proposer offers the Responder an amount from: {$0, $5, $10, $15, $20, $25, $30, $35, $40, $45, $50, $55, $60, $65, $70, $75, $80, $85, $90, $95, $100}.\nThe Proposer keeps the remainder.\nThe Responder can Accept or Reject.\n- If Accepted: Proposer gets $100 minus offer, Responder gets the offer.\n- If Rejected: both get $0.\n\nDetermine the SPE.", | |
| "solution": "Solving by backward induction:\n\n**Stage 2 (Responder's decision):**\n- For any offer x \u2265 $0: Accept gives Responder $x, Reject gives $0.\n- Responder accepts any offer \u2265 $0 (weakly dominant). \u2713\n\n**Stage 1 (Proposer's decision):**\n- Proposer knows Responder will accept any offer.\n- Proposer maximizes own payoff: $100 - offer.\n- Optimal offer: $0 (Proposer keeps $100). \u2713\n\n**Subgame Perfect Equilibrium:**\n- Proposer offers $0\n- Responder accepts (any offer \u2265 $0)\n- Payoffs: Proposer=$100, Responder=$0\n\n**Note:** The SPE prediction contrasts with experimental evidence where offers around 40-50% are common and low offers are frequently rejected, showing bounded rationality and fairness concerns.", | |
| "answer": "SPE: Offer=$0, Proposer gets $100, Responder gets $0", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "ultimatum", | |
| "bargaining", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-ultim-0020", | |
| "category": "sequential_game", | |
| "subcategory": "ultimatum_bargaining", | |
| "difficulty": "easy", | |
| "problem": "Consider an ultimatum game:\n\nA Proposer and a Responder divide $8.\nThe Proposer offers the Responder an amount from: {$0, $1, $2, $3, $4, $5, $6, $7, $8}.\nThe Proposer keeps the remainder.\nThe Responder can Accept or Reject.\n- If Accepted: Proposer gets $8 minus offer, Responder gets the offer.\n- If Rejected: both get $0.\n\nFind the Subgame Perfect Equilibrium.", | |
| "solution": "Solving by backward induction:\n\n**Stage 2 (Responder's decision):**\n- For any offer x \u2265 $0: Accept gives Responder $x, Reject gives $0.\n- Responder accepts any offer \u2265 $0 (weakly dominant). \u2713\n\n**Stage 1 (Proposer's decision):**\n- Proposer knows Responder will accept any offer.\n- Proposer maximizes own payoff: $8 - offer.\n- Optimal offer: $0 (Proposer keeps $8). \u2713\n\n**Subgame Perfect Equilibrium:**\n- Proposer offers $0\n- Responder accepts (any offer \u2265 $0)\n- Payoffs: Proposer=$8, Responder=$0\n\n**Note:** The SPE prediction contrasts with experimental evidence where offers around 40-50% are common and low offers are frequently rejected, showing bounded rationality and fairness concerns.", | |
| "answer": "SPE: Offer=$0, Proposer gets $8, Responder gets $0", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "ultimatum", | |
| "bargaining", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-simple-0045", | |
| "category": "sequential_game", | |
| "subcategory": "simple_2player", | |
| "difficulty": "medium", | |
| "problem": "Player 1 moves first in the following game, and Player 2 observes Player 1's choice before deciding:\n\nPlayer 1 chooses from: {A, B, C}\nIf Player 1 chooses A, Player 2 chooses from {X, Y, Z}:\n (A, X) \u2192 payoffs (0, 5) (Player 1, Player 2)\n (A, Y) \u2192 payoffs (8, 10) (Player 1, Player 2)\n (A, Z) \u2192 payoffs (4, 7) (Player 1, Player 2)\nIf Player 1 chooses B, Player 2 chooses from {X, Y, Z}:\n (B, X) \u2192 payoffs (-4, 9) (Player 1, Player 2)\n (B, Y) \u2192 payoffs (-3, 5) (Player 1, Player 2)\n (B, Z) \u2192 payoffs (3, 5) (Player 1, Player 2)\nIf Player 1 chooses C, Player 2 chooses from {X, Y}:\n (C, X) \u2192 payoffs (-2, 7) (Player 1, Player 2)\n (C, Y) \u2192 payoffs (-5, 9) (Player 1, Player 2)\n\nSolve for the Subgame Perfect Equilibrium.", | |
| "solution": "Solving by backward induction:\n\n**Stage 2 (Player 2's optimal responses):**\n- If Player 1 chose A: Player 2 compares payoffs [X\u21925, Y\u219210, Z\u21927]. Best response: Y (payoff 10). \u2713\n- If Player 1 chose B: Player 2 compares payoffs [X\u21929, Y\u21925, Z\u21925]. Best response: X (payoff 9). \u2713\n- If Player 1 chose C: Player 2 compares payoffs [X\u21927, Y\u21929]. Best response: Y (payoff 9). \u2713\n\n**Stage 1 (Player 1 anticipates Player 2's responses):**\n- A \u2192 P2 plays Y \u2192 payoffs (8, 10). P1 gets 8. \u2713 OPTIMAL\n- B \u2192 P2 plays X \u2192 payoffs (-4, 9). P1 gets -4. \n- C \u2192 P2 plays Y \u2192 payoffs (-5, 9). P1 gets -5. \n\n**Subgame Perfect Equilibrium:**\n- Player 1 plays A\n- Player 2's strategy: [Y after A, X after B, Y after C]\n- Equilibrium payoffs: (8, 10)", | |
| "answer": "SPE: P1=A, P2=[Y after A, X after B, Y after C], Payoffs=(8, 10)", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "extensive_form", | |
| "3_actions", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-3stage-0074", | |
| "category": "sequential_game", | |
| "subcategory": "three_stage", | |
| "difficulty": "medium", | |
| "problem": "Analyze this multi-stage game:\n\nStage 1: Player 1 chooses from {A, B}\nStage 2: Player 2 observes Stage 1 and chooses from {X, Y}\nStage 3: Player 1 observes Stages 1-2 and chooses from {L, R}\n\nPayoffs (Player 1, Player 2):\n\n (A, X, L) \u2192 (-5, -4)\n (A, X, R) \u2192 (-2, 8)\n (A, Y, L) \u2192 (9, 7)\n (A, Y, R) \u2192 (-2, 3)\n (B, X, L) \u2192 (10, -1)\n (B, X, R) \u2192 (1, -5)\n (B, Y, L) \u2192 (4, 8)\n (B, Y, R) \u2192 (-2, 3)\n\nUse backward induction to determine the optimal strategy at each decision point.", | |
| "solution": "Solving by backward induction:\n\n**Stage 3 (Player 1's optimal responses):**\n- After (A,X): compares [L\u2192-5, R\u2192-2]. Best: R (payoff -2). \u2713\n- After (A,Y): compares [L\u21929, R\u2192-2]. Best: L (payoff 9). \u2713\n- After (B,X): compares [L\u219210, R\u21921]. Best: L (payoff 10). \u2713\n- After (B,Y): compares [L\u21924, R\u2192-2]. Best: L (payoff 4). \u2713\n\n**Stage 2 (Player 2's optimal responses):**\n- After (A): compares [X\u21928, Y\u21927]. Best: X (payoff 8). \u2713\n- After (B): compares [X\u2192-1, Y\u21928]. Best: Y (payoff 8). \u2713\n\n**Stage 1 (Player 1's choice):**\n- A \u2192 sequence (A,X,R) \u2192 payoffs (-2, 8). Gets -2. \n- B \u2192 sequence (B,Y,L) \u2192 payoffs (4, 8). Gets 4. \u2713 OPTIMAL\n\n**Subgame Perfect Equilibrium:**\n- Equilibrium path: (B, Y, L)\n- Equilibrium payoffs: (4, 8)", | |
| "answer": "SPE path: (B, Y, L), Payoffs: (4, 8)", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "extensive_form", | |
| "three_stage", | |
| "2_player", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-3stage-0027", | |
| "category": "sequential_game", | |
| "subcategory": "three_stage", | |
| "difficulty": "medium", | |
| "problem": "In this game, three decisions are made sequentially:\n\nStage 1: Player 1 chooses from {A, B}\nStage 2: Player 2 observes Stage 1 and chooses from {X, Y}\nStage 3: Player 1 observes Stages 1-2 and chooses from {L, R}\n\nPayoffs (Player 1, Player 2):\n\n (A, X, L) \u2192 (10, -2)\n (A, X, R) \u2192 (4, 8)\n (A, Y, L) \u2192 (-3, -2)\n (A, Y, R) \u2192 (-1, 6)\n (B, X, L) \u2192 (4, 5)\n (B, X, R) \u2192 (9, 1)\n (B, Y, L) \u2192 (10, 6)\n (B, Y, R) \u2192 (10, -2)\n\nFind the SPE by working backwards from the final stage.", | |
| "solution": "Solving by backward induction:\n\n**Stage 3 (Player 1's optimal responses):**\n- After (A,X): compares [L\u219210, R\u21924]. Best: L (payoff 10). \u2713\n- After (A,Y): compares [L\u2192-3, R\u2192-1]. Best: R (payoff -1). \u2713\n- After (B,X): compares [L\u21924, R\u21929]. Best: R (payoff 9). \u2713\n- After (B,Y): compares [L\u219210, R\u219210]. Best: L (payoff 10). \u2713\n\n**Stage 2 (Player 2's optimal responses):**\n- After (A): compares [X\u2192-2, Y\u21926]. Best: Y (payoff 6). \u2713\n- After (B): compares [X\u21921, Y\u21926]. Best: Y (payoff 6). \u2713\n\n**Stage 1 (Player 1's choice):**\n- A \u2192 sequence (A,Y,R) \u2192 payoffs (-1, 6). Gets -1. \n- B \u2192 sequence (B,Y,L) \u2192 payoffs (10, 6). Gets 10. \u2713 OPTIMAL\n\n**Subgame Perfect Equilibrium:**\n- Equilibrium path: (B, Y, L)\n- Equilibrium payoffs: (10, 6)", | |
| "answer": "SPE path: (B, Y, L), Payoffs: (10, 6)", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "extensive_form", | |
| "three_stage", | |
| "2_player", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-3stage-0059", | |
| "category": "sequential_game", | |
| "subcategory": "three_stage", | |
| "difficulty": "hard", | |
| "problem": "Consider the following 3-stage sequential game:\n\nStage 1: Player 1 chooses from {A, B}\nStage 2: Player 2 observes Stage 1 and chooses from {X, Y}\nStage 3: Player 3 observes Stages 1-2 and chooses from {L, R}\n\nPayoffs (Player 1, Player 2, Player 3):\n\n (A, X, L) \u2192 (-5, 8, 0)\n (A, X, R) \u2192 (8, 0, -4)\n (A, Y, L) \u2192 (-2, 5, 1)\n (A, Y, R) \u2192 (1, 8, 3)\n (B, X, L) \u2192 (4, 4, 2)\n (B, X, R) \u2192 (-2, -4, 7)\n (B, Y, L) \u2192 (10, -1, -4)\n (B, Y, R) \u2192 (6, -5, 8)\n\nSolve for the Subgame Perfect Equilibrium using backward induction.", | |
| "solution": "Solving by backward induction:\n\n**Stage 3 (Player 3's optimal responses):**\n- After (A,X): compares [L\u21920, R\u2192-4]. Best: L (payoff 0). \u2713\n- After (A,Y): compares [L\u21921, R\u21923]. Best: R (payoff 3). \u2713\n- After (B,X): compares [L\u21922, R\u21927]. Best: R (payoff 7). \u2713\n- After (B,Y): compares [L\u2192-4, R\u21928]. Best: R (payoff 8). \u2713\n\n**Stage 2 (Player 2's optimal responses):**\n- After (A): compares [X\u21928, Y\u21928]. Best: X (payoff 8). \u2713\n- After (B): compares [X\u2192-4, Y\u2192-5]. Best: X (payoff -4). \u2713\n\n**Stage 1 (Player 1's choice):**\n- A \u2192 sequence (A,X,L) \u2192 payoffs (-5, 8, 0). Gets -5. \n- B \u2192 sequence (B,X,R) \u2192 payoffs (-2, -4, 7). Gets -2. \u2713 OPTIMAL\n\n**Subgame Perfect Equilibrium:**\n- Equilibrium path: (B, X, R)\n- Equilibrium payoffs: (-2, -4, 7)", | |
| "answer": "SPE path: (B, X, R), Payoffs: (-2, -4, 7)", | |
| "game_type": "sequential", | |
| "players": 3, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "extensive_form", | |
| "three_stage", | |
| "3_player", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-stack-0055", | |
| "category": "sequential_game", | |
| "subcategory": "stackelberg_competition", | |
| "difficulty": "hard", | |
| "problem": "Consider a Stackelberg duopoly:\n\nMarket demand: P = 24 - 2(q1 + q2)\nFirm 1 (Leader) marginal cost: c1 = 0\nFirm 2 (Follower) marginal cost: c2 = 0\nFirm 1 chooses quantity q1 first. Firm 2 observes q1 and then chooses q2.\n\nFind the Subgame Perfect Equilibrium quantities, prices, and profits.", | |
| "solution": "Solving by backward induction:\n\n**Stage 2 (Follower's best response):**\n- Firm 2 maximizes profit: \u03c02 = (P - c2) \u00d7 q2 = (24 - 2(q1 + q2) - 0) \u00d7 q2\n- FOC: 24 - 2\u00d7q1 - 4\u00d7q2 - 0 = 0\n- Best response: q2(q1) = (24 - 0 - 2\u00d7q1) / 4\n\n**Stage 1 (Leader's optimization):**\n- Firm 1 substitutes Firm 2's BR into its profit:\n- \u03c01 = (24/2 + 0/2 - 2\u00d7q1/2 - 0) \u00d7 q1\n- FOC: 24/2 + 0/2 - 2\u00d7q1 - 0 = 0\n- q1* = (24 + 0 - 0) / 4 = 6\n\n**Follower's quantity:**\n- q2* = (24 - 0 - 2\u00d76) / 4 = 3\n\n**Market outcome:**\n- Total output: Q = 6 + 3 = 9\n- Market price: P = 24 - 2\u00d79 = 6\n- Leader profit: \u03c01 = (6 - 0) \u00d7 6 = 36\n- Follower profit: \u03c02 = (6 - 0) \u00d7 3 = 18\n\n**Leader advantage:** Firm 1 produces more (6 vs 3) and earns higher profit (36 vs 18) due to first-mover advantage. \u2713", | |
| "answer": "q1*=6, q2*=3, P*=6, \u03c01=36, \u03c02=18", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "stackelberg", | |
| "duopoly", | |
| "cournot", | |
| "industrial_organization", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-stack-0073", | |
| "category": "sequential_game", | |
| "subcategory": "stackelberg_competition", | |
| "difficulty": "hard", | |
| "problem": "In a Stackelberg competition, Firm 1 (leader) chooses quantity first, then Firm 2 (follower) observes and chooses:\n\nMarket demand: P = 36 - 3(q1 + q2)\nFirm 1 (Leader) marginal cost: c1 = 0\nFirm 2 (Follower) marginal cost: c2 = 0\nFirm 1 chooses quantity q1 first. Firm 2 observes q1 and then chooses q2.\n\nSolve for the SPE.", | |
| "solution": "Solving by backward induction:\n\n**Stage 2 (Follower's best response):**\n- Firm 2 maximizes profit: \u03c02 = (P - c2) \u00d7 q2 = (36 - 3(q1 + q2) - 0) \u00d7 q2\n- FOC: 36 - 3\u00d7q1 - 6\u00d7q2 - 0 = 0\n- Best response: q2(q1) = (36 - 0 - 3\u00d7q1) / 6\n\n**Stage 1 (Leader's optimization):**\n- Firm 1 substitutes Firm 2's BR into its profit:\n- \u03c01 = (36/2 + 0/2 - 3\u00d7q1/2 - 0) \u00d7 q1\n- FOC: 36/2 + 0/2 - 3\u00d7q1 - 0 = 0\n- q1* = (36 + 0 - 0) / 6 = 6\n\n**Follower's quantity:**\n- q2* = (36 - 0 - 3\u00d76) / 6 = 3\n\n**Market outcome:**\n- Total output: Q = 6 + 3 = 9\n- Market price: P = 36 - 3\u00d79 = 9\n- Leader profit: \u03c01 = (9 - 0) \u00d7 6 = 54\n- Follower profit: \u03c02 = (9 - 0) \u00d7 3 = 27\n\n**Leader advantage:** Firm 1 produces more (6 vs 3) and earns higher profit (54 vs 27) due to first-mover advantage. \u2713", | |
| "answer": "q1*=6, q2*=3, P*=9, \u03c01=54, \u03c02=27", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "stackelberg", | |
| "duopoly", | |
| "cournot", | |
| "industrial_organization", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-seq-ultim-0009", | |
| "category": "sequential_game", | |
| "subcategory": "ultimatum_bargaining", | |
| "difficulty": "easy", | |
| "problem": "In this bargaining game, the proposer makes a take-it-or-leave-it offer:\n\nA Proposer and a Responder divide $8.\nThe Proposer offers the Responder an amount from: {$0, $1, $2, $3, $4, $5, $6, $7, $8}.\nThe Proposer keeps the remainder.\nThe Responder can Accept or Reject.\n- If Accepted: Proposer gets $8 minus offer, Responder gets the offer.\n- If Rejected: both get $0.\n\nDetermine the SPE.", | |
| "solution": "Solving by backward induction:\n\n**Stage 2 (Responder's decision):**\n- For any offer x \u2265 $0: Accept gives Responder $x, Reject gives $0.\n- Responder accepts any offer \u2265 $0 (weakly dominant). \u2713\n\n**Stage 1 (Proposer's decision):**\n- Proposer knows Responder will accept any offer.\n- Proposer maximizes own payoff: $8 - offer.\n- Optimal offer: $0 (Proposer keeps $8). \u2713\n\n**Subgame Perfect Equilibrium:**\n- Proposer offers $0\n- Responder accepts (any offer \u2265 $0)\n- Payoffs: Proposer=$8, Responder=$0\n\n**Note:** The SPE prediction contrasts with experimental evidence where offers around 40-50% are common and low offers are frequently rejected, showing bounded rationality and fairness concerns.", | |
| "answer": "SPE: Offer=$0, Proposer gets $8, Responder gets $0", | |
| "game_type": "sequential", | |
| "players": 2, | |
| "tags": [ | |
| "sequential", | |
| "backward_induction", | |
| "subgame_perfect", | |
| "ultimatum", | |
| "bargaining", | |
| "pure_strategy" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-2x2-saddle-0015", | |
| "category": "zero_sum", | |
| "subcategory": "saddle_point", | |
| "difficulty": "easy", | |
| "problem": "Analyze this zero-sum game for saddle points:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | -8 | -6\nDown | -4 | 6\n\nWhat is the optimal pure strategy for each player?", | |
| "solution": "Analyzing this zero-sum game for saddle points:\n\nStep 1: For each cell, check if it is both the minimum of its row and the maximum of its column:\n (Up, Left): value=-8, row_min=-8, col_max=-4 \u2717\n (Down, Left): value=-4, row_min=-4, col_max=-4 \u2190 Saddle point! \u2713\n (Down, Right): value=6, row_min=-4, col_max=6 \u2717\n\nSaddle point(s) found: (Down, Left) with value -4.\nThe maximin value (Player 1) is -4 (strategy: Down).\nThe minimax value (Player 2) is -4 (strategy: Left).\nSince maximin = minimax = -4, the value of the game is -4. \u2713\nPlayer 1's optimal strategy: Down. Player 2's optimal strategy: Left.", | |
| "answer": "Saddle points: [(Down, Left)], Game value: -4", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "minimax", | |
| "pure_strategy", | |
| "saddle_point", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-2x2-value-0007", | |
| "category": "zero_sum", | |
| "subcategory": "game_value", | |
| "difficulty": "easy", | |
| "problem": "What is the value of this zero-sum game? Justify your answer:\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | 3 | -5\nDown | 3 | 4", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Up: min[3, -5] = -5\n Down: min[3, 4] = 3\n Maximin value = max of row minima = 3 (Player 1 plays Down)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n Left: max[3, 3] = 3\n Right: max[-5, 4] = 4\n Minimax value = min of column maxima = 3 (Player 2 plays Left)\n\nStep 3: Maximin (3) = Minimax (3). A saddle point exists! \u2713\n Saddle point(s): (Down, Left) with game value 3.\n Player 1's optimal pure strategy: Down\n Player 2's optimal pure strategy: Left", | |
| "answer": "Game value: 3.0", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "game_value", | |
| "minimax", | |
| "pure_strategy", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-2x2-minimax-0001", | |
| "category": "zero_sum", | |
| "subcategory": "minimax", | |
| "difficulty": "easy", | |
| "problem": "Consider the following zero-sum game (payoffs for Player 1):\n\nPlayer 1 \\ Player 2 | Left | Right\n--- | --- | ---\nUp | 8 | 2\nDown | -7 | 7\n\nCompute the maximin and minimax values. Does a saddle point exist?", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Up: min[8, 2] = 2\n Down: min[-7, 7] = -7\n Maximin value = max of row minima = 2 (Player 1 plays Up)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n Left: max[8, -7] = 8\n Right: max[2, 7] = 7\n Minimax value = min of column maxima = 7 (Player 2 plays Right)\n\nStep 3: Maximin (2) \u2260 Minimax (7). No saddle point exists.\n Players must use mixed strategies to find the optimal solution.\n\nStep 4: Computing the optimal mixed strategy solution:\n Player 1's optimal mixed strategy: Up with probability 0.7000, Down with probability 0.3000.\n Player 2's optimal mixed strategy: Left with probability 0.2500, Right with probability 0.7500.\n The value of the game is 3.5000. \u2713\n At this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.", | |
| "answer": "Maximin: 2, Minimax: 7, Saddle: No, Mixed solution: P1=[0.7, 0.3], P2=[0.25, 0.75], Value=3.5000", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "2x2", | |
| "minimax", | |
| "mixed_strategy", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-3x4-value-0012", | |
| "category": "zero_sum", | |
| "subcategory": "game_value", | |
| "difficulty": "medium", | |
| "problem": "What is the value of this zero-sum game? Justify your answer:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | -8 | 5 | -5 | 3\nMiddle | -3 | 2 | 3 | 1\nBottom | -2 | -2 | 2 | -5", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Top: min[-8, 5, -5, 3] = -8\n Middle: min[-3, 2, 3, 1] = -3\n Bottom: min[-2, -2, 2, -5] = -5\n Maximin value = max of row minima = -3 (Player 1 plays Middle)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n C1: max[-8, -3, -2] = -2\n C2: max[5, 2, -2] = 5\n C3: max[-5, 3, 2] = 3\n C4: max[3, 1, -5] = 3\n Minimax value = min of column maxima = -2 (Player 2 plays C1)\n\nStep 3: Maximin (-3) \u2260 Minimax (-2). No saddle point exists.\n Players must use mixed strategies to find the optimal solution.\n\nStep 4: Computing the optimal mixed strategy solution:\n Player 1's optimal mixed strategy: Middle with probability 0.4286, Bottom with probability 0.5714.\n Player 2's optimal mixed strategy: C1 with probability 0.8571, C4 with probability 0.1429.\n The value of the game is -2.4286. \u2713\n At this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.", | |
| "answer": "Game value: -2.428571, P1=[0.0, 0.428571, 0.571429], P2=[0.857143, 0.0, 0.0, 0.142857]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "game_value", | |
| "minimax", | |
| "mixed_strategy", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-3x4-value-0014", | |
| "category": "zero_sum", | |
| "subcategory": "game_value", | |
| "difficulty": "medium", | |
| "problem": "Find the value of the following zero-sum game:\n\nPlayer 1 \\ Player 2 | C1 | C2 | C3 | C4\n--- | --- | --- | --- | ---\nTop | 3 | -8 | -8 | 5\nMiddle | -5 | -4 | 2 | 4\nBottom | 7 | 4 | -7 | 7\n\nSpecify whether pure or mixed strategies are required.", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Top: min[3, -8, -8, 5] = -8\n Middle: min[-5, -4, 2, 4] = -5\n Bottom: min[7, 4, -7, 7] = -7\n Maximin value = max of row minima = -5 (Player 1 plays Middle)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n C1: max[3, -5, 7] = 7\n C2: max[-8, -4, 4] = 4\n C3: max[-8, 2, -7] = 2\n C4: max[5, 4, 7] = 7\n Minimax value = min of column maxima = 2 (Player 2 plays C3)\n\nStep 3: Maximin (-5) \u2260 Minimax (2). No saddle point exists.\n Players must use mixed strategies to find the optimal solution.\n\nStep 4: Computing the optimal mixed strategy solution:\n Player 1's optimal mixed strategy: Middle with probability 0.6471, Bottom with probability 0.3529.\n Player 2's optimal mixed strategy: C2 with probability 0.5294, C3 with probability 0.4706.\n The value of the game is -1.1765. \u2713\n At this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.", | |
| "answer": "Game value: -1.176471, P1=[0.0, 0.647059, 0.352941], P2=[0.0, 0.529412, 0.470588, 0.0]", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x4", | |
| "game_value", | |
| "minimax", | |
| "mixed_strategy", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-3x3-saddle-0015", | |
| "category": "zero_sum", | |
| "subcategory": "saddle_point", | |
| "difficulty": "medium", | |
| "problem": "In the zero-sum game below, identify any saddle points and compute the game value:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | 6 | 8 | 2\nMiddle | 8 | 4 | -8\nBottom | -7 | 0 | -6", | |
| "solution": "Analyzing this zero-sum game for saddle points:\n\nStep 1: For each cell, check if it is both the minimum of its row and the maximum of its column:\n (Top, Center): value=8, row_min=2, col_max=8 \u2717\n (Top, Right): value=2, row_min=2, col_max=2 \u2190 Saddle point! \u2713\n (Middle, Left): value=8, row_min=-8, col_max=8 \u2717\n (Middle, Right): value=-8, row_min=-8, col_max=2 \u2717\n (Bottom, Left): value=-7, row_min=-7, col_max=8 \u2717\n\nSaddle point(s) found: (Top, Right) with value 2.\nThe maximin value (Player 1) is 2 (strategy: Top).\nThe minimax value (Player 2) is 2 (strategy: Right).\nSince maximin = minimax = 2, the value of the game is 2. \u2713\nPlayer 1's optimal strategy: Top. Player 2's optimal strategy: Right.", | |
| "answer": "Saddle points: [(Top, Right)], Game value: 2", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "minimax", | |
| "pure_strategy", | |
| "saddle_point", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-3x3-mixed-0015", | |
| "category": "zero_sum", | |
| "subcategory": "mixed_strategy_minimax", | |
| "difficulty": "hard", | |
| "problem": "The following zero-sum game has no saddle point:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | -3 | 2 | -4\nMiddle | 6 | 0 | 5\nBottom | -4 | 0 | 0\n\nFind the optimal mixed strategy for each player and the value of the game.", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Top: min[-3, 2, -4] = -4\n Middle: min[6, 0, 5] = 0\n Bottom: min[-4, 0, 0] = -4\n Maximin value = max of row minima = 0 (Player 1 plays Middle)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n Left: max[-3, 6, -4] = 6\n Center: max[2, 0, 0] = 2\n Right: max[-4, 5, 0] = 5\n Minimax value = min of column maxima = 2 (Player 2 plays Center)\n\nStep 3: Maximin (0) \u2260 Minimax (2). No saddle point exists.\n Players must use mixed strategies to find the optimal solution.\n\nStep 4: Computing the optimal mixed strategy solution:\n Player 1's optimal mixed strategy: Top with probability 0.4545, Middle with probability 0.5455.\n Player 2's optimal mixed strategy: Center with probability 0.8182, Right with probability 0.1818.\n The value of the game is 0.9091. \u2713\n At this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.", | |
| "answer": "P1=[0.4545, 0.5455, 0.0000], P2=[0.0000, 0.8182, 0.1818], Value=0.9091", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "minimax", | |
| "mixed_strategy", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-3x3-mixed-0003", | |
| "category": "zero_sum", | |
| "subcategory": "mixed_strategy_minimax", | |
| "difficulty": "hard", | |
| "problem": "Solve the following zero-sum game using mixed strategies:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | -2 | -3 | 6\nMiddle | 2 | -4 | 0\nBottom | 4 | 1 | -1\n\nDetermine the optimal randomization and the expected game value.", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Top: min[-2, -3, 6] = -3\n Middle: min[2, -4, 0] = -4\n Bottom: min[4, 1, -1] = -1\n Maximin value = max of row minima = -1 (Player 1 plays Bottom)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n Left: max[-2, 2, 4] = 4\n Center: max[-3, -4, 1] = 1\n Right: max[6, 0, -1] = 6\n Minimax value = min of column maxima = 1 (Player 2 plays Center)\n\nStep 3: Maximin (-1) \u2260 Minimax (1). No saddle point exists.\n Players must use mixed strategies to find the optimal solution.\n\nStep 4: Computing the optimal mixed strategy solution:\n Player 1's optimal mixed strategy: Top with probability 0.1818, Bottom with probability 0.8182.\n Player 2's optimal mixed strategy: Center with probability 0.6364, Right with probability 0.3636.\n The value of the game is 0.2727. \u2713\n At this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.", | |
| "answer": "P1=[0.1818, 0.0000, 0.8182], P2=[0.0000, 0.6364, 0.3636], Value=0.2727", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "minimax", | |
| "mixed_strategy", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-3x3-mixed-0021", | |
| "category": "zero_sum", | |
| "subcategory": "mixed_strategy_minimax", | |
| "difficulty": "hard", | |
| "problem": "Solve the following zero-sum game using mixed strategies:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | 3 | 5 | 1\nMiddle | -2 | 3 | 5\nBottom | -2 | -2 | -6\n\nDetermine the optimal randomization and the expected game value.", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Top: min[3, 5, 1] = 1\n Middle: min[-2, 3, 5] = -2\n Bottom: min[-2, -2, -6] = -6\n Maximin value = max of row minima = 1 (Player 1 plays Top)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n Left: max[3, -2, -2] = 3\n Center: max[5, 3, -2] = 5\n Right: max[1, 5, -6] = 5\n Minimax value = min of column maxima = 3 (Player 2 plays Left)\n\nStep 3: Maximin (1) \u2260 Minimax (3). No saddle point exists.\n Players must use mixed strategies to find the optimal solution.\n\nStep 4: Computing the optimal mixed strategy solution:\n Player 1's optimal mixed strategy: Top with probability 0.7778, Middle with probability 0.2222.\n Player 2's optimal mixed strategy: Left with probability 0.4444, Right with probability 0.5556.\n The value of the game is 1.8889. \u2713\n At this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.", | |
| "answer": "P1=[0.7778, 0.2222, 0.0000], P2=[0.4444, 0.0000, 0.5556], Value=1.8889", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "minimax", | |
| "mixed_strategy", | |
| "zero_sum" | |
| ] | |
| }, | |
| { | |
| "id": "gt-zs-3x3-mixed-0010", | |
| "category": "zero_sum", | |
| "subcategory": "mixed_strategy_minimax", | |
| "difficulty": "hard", | |
| "problem": "The following zero-sum game has no saddle point:\n\nPlayer 1 \\ Player 2 | Left | Center | Right\n--- | --- | --- | ---\nTop | -4 | 3 | 0\nMiddle | 3 | -4 | -3\nBottom | -5 | -4 | 2\n\nFind the optimal mixed strategy for each player and the value of the game.", | |
| "solution": "Applying the minimax theorem to this zero-sum game:\n\nStep 1: Compute row minima (worst case for Player 1 per strategy):\n Top: min[-4, 3, 0] = -4\n Middle: min[3, -4, -3] = -4\n Bottom: min[-5, -4, 2] = -5\n Maximin value = max of row minima = -4 (Player 1 plays Top)\n\nStep 2: Compute column maxima (worst case for Player 2 per strategy):\n Left: max[-4, 3, -5] = 3\n Center: max[3, -4, -4] = 3\n Right: max[0, -3, 2] = 2\n Minimax value = min of column maxima = 2 (Player 2 plays Right)\n\nStep 3: Maximin (-4) \u2260 Minimax (2). No saddle point exists.\n Players must use mixed strategies to find the optimal solution.\n\nStep 4: Computing the optimal mixed strategy solution:\n Player 1's optimal mixed strategy: Top with probability 0.4216, Middle with probability 0.4412, Bottom with probability 0.1373.\n Player 2's optimal mixed strategy: Left with probability 0.3431, Center with probability 0.1078, Right with probability 0.5490.\n The value of the game is -1.0490. \u2713\n At this equilibrium, each player's mixture makes the opponent indifferent among their active strategies.", | |
| "answer": "P1=[0.4216, 0.4412, 0.1373], P2=[0.3431, 0.1078, 0.5490], Value=-1.0490", | |
| "game_type": "simultaneous", | |
| "players": 2, | |
| "tags": [ | |
| "3x3", | |
| "minimax", | |
| "mixed_strategy", | |
| "zero_sum" | |
| ] | |
| } | |
| ] |