<LEAN_FILE>:104:30: error(lean.unknownIdentifier): Unknown identifier `OProverMissing4cc58c818c.value`
<LEAN_FILE>:103:0: error: unsolved goals
X : Type u
Y : Type v
inst✝¹ : TopologicalSpace X
inst✝ : TopologicalSpace Y
f : X → Y
⊢ IsProperMap f ↔ Continuous f ∧ ∀ (Z : Type u) [inst : TopologicalSpace Z], IsClosedMap (Prod.map f id)

Response:
by
  constructor <;> intro H
  · exact ⟨H.continuous, fun Z ↦ H.universally_closed _⟩
  · rw [isProperMap_iff_isClosedMap_ultrafilter]
    exact ⟨H.1, H.2 _⟩

[User]
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Topology.Compactification.StoneCech
public import Mathlib.Topology.Filter
public import Mathlib.Topology.Maps.Proper.Basic

Namespace:
(root)

Local safe context:
/-
Copyright (c) 2023 Anatole Dedecker. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anatole Dedecker, Etienne Marion
-/
/-!
# A map is proper iff it is continuous and universally closed
-/

public section

open Filter

universe u v

/-- A map `f : X → Y` is proper if and only if it is continuous and the map
`(Prod.map f id : X × Filter X → Y × Filter X)` is closed. This is stronger than
`isProperMap_iff_universally_closed` since it shows that there's only one space to check to get
properness, but in most cases it doesn't matter. -/
theorem isProperMap_iff_isClosedMap_filter {X : Type u} {Y : Type v} [TopologicalSpace X]
    [TopologicalSpace Y] {f : X → Y} :
    IsProperMap f ↔ Continuous f ∧ IsClosedMap
      (Prod.map f id : X × Filter X → Y × Filter X) := by
  constructor <;> intro H
  -- The direct implication is clear.
  · exact ⟨H.continuous, H.universally_closed _⟩
  · rw [isProperMap_iff_ultrafilter]
  -- Let `𝒰 : Ultrafilter X`, and assume that `f` tends to some `y` along `𝒰`.
    refine ⟨H.1, fun 𝒰 y hy ↦ ?_⟩
  -- In `X × Filter X`, consider the closed set `F := closure {(x, ℱ) | ℱ = pure x}`
    let F : Set (X × Filter X) := closure {xℱ | xℱ.2 = pure xℱ.1}
  -- Since `f × id` is closed, the set `(f × id) '' F` is also closed.
    have := H.2 F isClosed_closure
  -- Let us show that `(y, 𝒰) ∈ (f × id) '' F`.
    have : (y, ↑𝒰) ∈ Prod.map f id '' F :=
  -- Note that, by the properties of the topology on `Filter X`, the function `pure : X → Filter X`
  -- tends to the point `𝒰` of `Filter X` along the filter `𝒰` on `X`. Since `f` tends to `y` along
  -- `𝒰`, we get that the function `(f, pure) : X → (Y, Filter X)` tends to `(y, 𝒰)` along
  -- `𝒰`. Furthermore, each `(f, pure)(x) = (f × id)(x, pure x)` is clearly an element of
  -- the closed set `(f × id) '' F`, thus the limit `(y, 𝒰)` also belongs to that set.
      this.mem_of_tendsto (hy.prodMk_nhds (Filter.tendsto_pure_self (𝒰 : Filter X)))
        (Eventually.of_forall fun x ↦ ⟨⟨x, pure x⟩, subset_closure rfl, rfl⟩)
  -- The above shows that `(y, 𝒰) = (f x, 𝒰)`, for some `x : X` such that `(x, 𝒰) ∈ F`.
    rcases this with ⟨⟨x, _⟩, hx, ⟨_, _⟩⟩
  -- We already know that `f x = y`, so to finish the proof we just have to check that `𝒰` tends
  -- to `x`. So, for `U ∈ 𝓝 x` arbitrary, let's show that `U ∈ 𝒰`. Since `𝒰` is an ultrafilter,
  -- it is enough to show that `Uᶜ` is not in `𝒰`.
    refine ⟨x, rfl, fun U hU ↦ Ultrafilter.compl_notMem_iff.mp fun hUc ↦ ?_⟩
    rw [mem_closure_iff_nhds] at hx
  -- Indeed, if that was the case, the set `V := {𝒢 : Filter X | Uᶜ ∈ 𝒢}` would be a neighborhood
  -- of `𝒰` in `Filter X`, hence `U ×ˢ V` would be a neighborhood of `(x, 𝒰) : X × Filter X`.
  -- But recall that `(x, 𝒰) ∈ F = closure {(x, ℱ) | ℱ = pure x}`, so the neighborhood `U ×ˢ V`
  -- must contain some element of the form `(z, pure z)`. In other words, we have `z ∈ U` and
  -- `Uᶜ ∈ pure z`, which means `z ∈ Uᶜ` by the definition of pure.
  -- This is a contradiction, which completes the proof.
    rcases hx (U ×ˢ {𝒢 | Uᶜ ∈ 𝒢}) (prod_mem_nhds hU (isOpen_setOf_mem.mem_nhds hUc)) with
      ⟨⟨z, 𝒢⟩, ⟨⟨hz : z ∈ U, hz' : Uᶜ ∈ 𝒢⟩, rfl : 𝒢 = pure z⟩⟩
    exact hz' hz

/-- A map `f : X → Y` is proper if and only if it is continuous and the map
`(Prod.map f id : X × Ultrafilter X → Y × Ultrafilter X)` is closed. This is stronger than
`isProperMap_iff_universally_closed` since it shows that there's only one space to check to get
properness, but in most cases it doesn't matter. -/
theorem isProperMap_iff_isClosedMap_ultrafilter {X : Type u} {Y : Type v} [TopologicalSpace X]
    [TopologicalSpace Y] {f : X → Y} :
    IsProperMap f ↔ Continuous f ∧ IsClosedMap
      (Prod.map f id : X × Ultrafilter X → Y × Ultrafilter X) := by
  -- The proof is basically the same as above.
  constructor <;> intro H
  · exact ⟨H.continuous, H.universally_closed _⟩
  · rw [isProperMap_iff_ultrafilter]
    refine ⟨H.1, fun 𝒰 y hy ↦ ?_⟩
    let F : Set (X × Ultrafilter X) := closure {xℱ | xℱ.2 = pure xℱ.1}
    have := H.2 F isClosed_closure
    have : (y, 𝒰) ∈ Prod.map f id '' F :=
      this.mem_of_tendsto (hy.prodMk_nhds (Ultrafilter.tendsto_pure_self 𝒰))
        (Eventually.of_forall fun x ↦ ⟨⟨x, pure x⟩, subset_closure rfl, rfl⟩)
    rcases this with ⟨⟨x, _⟩, hx, ⟨_, _⟩⟩
    refine ⟨x, rfl, fun U hU ↦ Ultrafilter.compl_notMem_iff.mp fun hUc ↦ ?_⟩
    rw [mem_closure_iff_nhds] at hx
    rcases hx (U ×ˢ {𝒢 | Uᶜ ∈ 𝒢}) (prod_mem_nhds hU ((ultrafilter_isOpen_basic _).mem_nhds hUc))
      with ⟨⟨y, 𝒢⟩, ⟨⟨hy : y ∈ U, hy' : Uᶜ ∈ 𝒢⟩, rfl : 𝒢 = pure y⟩⟩
    exact hy' hy

/-- A map `f : X → Y` is proper if and only if it is continuous and **universally closed**, in the
sense that for any topological space `Z`, the map `Prod.map f id : X × Z → Y × Z` is closed. Note
that `Z` lives in the same universe as `X` here, but `IsProperMap.universally_closed` does not
have this restriction.

This is taken as the definition of properness in
[N. Bourbaki, *General Topology*][bourbaki1966]. -/

Target:
theorem isProperMap_iff_universally_closed {X : Type u} {Y : Type v} [TopologicalSpace X]
    [TopologicalSpace Y] {f : X → Y} :
    IsProperMap f ↔ Continuous f ∧ ∀ (Z : Type u) [TopologicalSpace Z],
      IsClosedMap (Prod.map f id : X × Z → Y × Z) :=

Failed candidate:
by
  have __repair_4cc58c818c := OProverMissing4cc58c818c.value
  constructor <;> intro H
  · exact ⟨H.continuous, fun Z ↦ H.universally_closed _⟩
  · rw [isProperMap_iff_isClosedMap_ultrafilter]
    exact ⟨H.1, H.2 _⟩

Structured Lean error:
{"kind": "unknown_identifier_namespace_import", "message": "<LEAN_FILE>:104:30: error(lean.unknownIdentifier): Unknown identifier `OProverMissing4cc58c818c.value`\n<LEAN_FILE>:103:0: error: unsolved goals\nX : Type u\nY : Type v\ninst✝¹ : TopologicalSpace X\ninst✝ : TopologicalSpace Y\nf : X → Y\n⊢ IsProperMap f ↔ Continuous f ∧ ∀ (Z : Type u) [inst : TopologicalSpace Z], IsClosedMap (Prod.map f id)", "returncode": 1}

Corrected proof:

[Assistant]
by
  constructor <;> intro H
  · exact ⟨H.continuous, fun Z ↦ H.universally_closed _⟩
  · rw [isProperMap_iff_isClosedMap_ultrafilter]
    exact ⟨H.1, H.2 _⟩

Prompt:
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Topology.Compactification.StoneCech
public import Mathlib.Topology.Filter
public import Mathlib.Topology.Maps.Proper.Basic

Namespace:
(root)

Local safe context:
/-
Copyright (c) 2023 Anatole Dedecker. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Anatole Dedecker, Etienne Marion
-/
/-!
# A map is proper iff it is continuous and universally closed
-/

public section

open Filter

universe u v

/-- A map `f : X → Y` is proper if and only if it is continuous and the map
`(Prod.map f id : X × Filter X → Y × Filter X)` is closed. This is stronger than
`isProperMap_iff_universally_closed` since it shows that there's only one space to check to get
properness, but in most cases it doesn't matter. -/
theorem isProperMap_iff_isClosedMap_filter {X : Type u} {Y : Type v} [TopologicalSpace X]
    [TopologicalSpace Y] {f : X → Y} :
    IsProperMap f ↔ Continuous f ∧ IsClosedMap
      (Prod.map f id : X × Filter X → Y × Filter X) := by
  constructor <;> intro H
  -- The direct implication is clear.
  · exact ⟨H.continuous, H.universally_closed _⟩
  · rw [isProperMap_iff_ultrafilter]
  -- Let `𝒰 : Ultrafilter X`, and assume that `f` tends to some `y` along `𝒰`.
    refine ⟨H.1, fun 𝒰 y hy ↦ ?_⟩
  -- In `X × Filter X`, consider the closed set `F := closure {(x, ℱ) | ℱ = pure x}`
    let F : Set (X × Filter X) := closure {xℱ | xℱ.2 = pure xℱ.1}
  -- Since `f × id` is closed, the set `(f × id) '' F` is also closed.
    have := H.2 F isClosed_closure
  -- Let us show that `(y, 𝒰) ∈ (f × id) '' F`.
    have : (y, ↑𝒰) ∈ Prod.map f id '' F :=
  -- Note that, by the properties of the topology on `Filter X`, the function `pure : X → Filter X`
  -- tends to the point `𝒰` of `Filter X` along the filter `𝒰` on `X`. Since `f` tends to `y` along
  -- `𝒰`, we get that the function `(f, pure) : X → (Y, Filter X)` tends to `(y, 𝒰)` along
  -- `𝒰`. Furthermore, each `(f, pure)(x) = (f × id)(x, pure x)` is clearly an element of
  -- the closed set `(f × id) '' F`, thus the limit `(y, 𝒰)` also belongs to that set.
      this.mem_of_tendsto (hy.prodMk_nhds (Filter.tendsto_pure_self (𝒰 : Filter X)))
        (Eventually.of_forall fun x ↦ ⟨⟨x, pure x⟩, subset_closure rfl, rfl⟩)
  -- The above shows that `(y, 𝒰) = (f x, 𝒰)`, for some `x : X` such that `(x, 𝒰) ∈ F`.
    rcases this with ⟨⟨x, _⟩, hx, ⟨_, _⟩⟩
  -- We already know that `f x = y`, so to finish the proof we just have to check that `𝒰` tends
  -- to `x`. So, for `U ∈ 𝓝 x` arbitrary, let's show that `U ∈ 𝒰`. Since `𝒰` is an ultrafilter,
  -- it is enough to show that `Uᶜ` is not in `𝒰`.
    refine ⟨x, rfl, fun U hU ↦ Ultrafilter.compl_notMem_iff.mp fun hUc ↦ ?_⟩
    rw [mem_closure_iff_nhds] at hx
  -- Indeed, if that was the case, the set `V := {𝒢 : Filter X | Uᶜ ∈ 𝒢}` would be a neighborhood
  -- of `𝒰` in `Filter X`, hence `U ×ˢ V` would be a neighborhood of `(x, 𝒰) : X × Filter X`.
  -- But recall that `(x, 𝒰) ∈ F = closure {(x, ℱ) | ℱ = pure x}`, so the neighborhood `U ×ˢ V`
  -- must contain some element of the form `(z, pure z)`. In other words, we have `z ∈ U` and
  -- `Uᶜ ∈ pure z`, which means `z ∈ Uᶜ` by the definition of pure.
  -- This is a contradiction, which completes the proof.
    rcases hx (U ×ˢ {𝒢 | Uᶜ ∈ 𝒢}) (prod_mem_nhds hU (isOpen_setOf_mem.mem_nhds hUc)) with
      ⟨⟨z, 𝒢⟩, ⟨⟨hz : z ∈ U, hz' : Uᶜ ∈ 𝒢⟩, rfl : 𝒢 = pure z⟩⟩
    exact hz' hz

/-- A map `f : X → Y` is proper if and only if it is continuous and the map
`(Prod.map f id : X × Ultrafilter X → Y × Ultrafilter X)` is closed. This is stronger than
`isProperMap_iff_universally_closed` since it shows that there's only one space to check to get
properness, but in most cases it doesn't matter. -/
theorem isProperMap_iff_isClosedMap_ultrafilter {X : Type u} {Y : Type v} [TopologicalSpace X]
    [TopologicalSpace Y] {f : X → Y} :
    IsProperMap f ↔ Continuous f ∧ IsClosedMap
      (Prod.map f id : X × Ultrafilter X → Y × Ultrafilter X) := by
  -- The proof is basically the same as above.
  constructor <;> intro H
  · exact ⟨H.continuous, H.universally_closed _⟩
  · rw [isProperMap_iff_ultrafilter]
    refine ⟨H.1, fun 𝒰 y hy ↦ ?_⟩
    let F : Set (X × Ultrafilter X) := closure {xℱ | xℱ.2 = pure xℱ.1}
    have := H.2 F isClosed_closure
    have : (y, 𝒰) ∈ Prod.map f id '' F :=
      this.mem_of_tendsto (hy.prodMk_nhds (Ultrafilter.tendsto_pure_self 𝒰))
        (Eventually.of_forall fun x ↦ ⟨⟨x, pure x⟩, subset_closure rfl, rfl⟩)
    rcases this with ⟨⟨x, _⟩, hx, ⟨_, _⟩⟩
    refine ⟨x, rfl, fun U hU ↦ Ultrafilter.compl_notMem_iff.mp fun hUc ↦ ?_⟩
    rw [mem_closure_iff_nhds] at hx
    rcases hx (U ×ˢ {𝒢 | Uᶜ ∈ 𝒢}) (prod_mem_nhds hU ((ultrafilter_isOpen_basic _).mem_nhds hUc))
      with ⟨⟨y, 𝒢⟩, ⟨⟨hy : y ∈ U, hy' : Uᶜ ∈ 𝒢⟩, rfl : 𝒢 = pure y⟩⟩
    exact hy' hy

/-- A map `f : X → Y` is proper if and only if it is continuous and **universally closed**, in the
sense that for any topological space `Z`, the map `Prod.map f id : X × Z → Y × Z` is closed. Note
that `Z` lives in the same universe as `X` here, but `IsProperMap.universally_closed` does not
have this restriction.

This is taken as the definition of properness in
[N. Bourbaki, *General Topology*][bourbaki1966]. -/

Target:
theorem isProperMap_iff_universally_closed {X : Type u} {Y : Type v} [TopologicalSpace X]
    [TopologicalSpace Y] {f : X → Y} :
    IsProperMap f ↔ Continuous f ∧ ∀ (Z : Type u) [TopologicalSpace Z],
      IsClosedMap (Prod.map f id : X × Z → Y × Z) :=

Failed candidate:
by
  have __repair_4cc58c818c := OProverMissing4cc58c818c.value
  constructor <;> intro H
  · exact ⟨H.continuous, fun Z ↦ H.universally_closed _⟩
  · rw [isProperMap_iff_isClosedMap_ultrafilter]
    exact ⟨H.1, H.2 _⟩

Structured Lean error:
{"kind": "unknown_identifier_namespace_import", "message": "<LEAN_FILE>:104:30: error(lean.unknownIdentifier): Unknown identifier `OProverMissing4cc58c818c.value`\n<LEAN_FILE>:103:0: error: unsolved goals\nX : Type u\nY : Type v\ninst✝¹ : TopologicalSpace X\ninst✝ : TopologicalSpace Y\nf : X → Y\n⊢ IsProperMap f ↔ Continuous f ∧ ∀ (Z : Type u) [inst : TopologicalSpace Z], IsClosedMap (Prod.map f id)", "returncode": 1}

Corrected proof:


<LEAN_FILE>:127:43: error: unsolved goals
E : Type u_1
X : Type u_2
inst✝³ : TopologicalSpace E
inst✝² : TopologicalSpace X
f : E → X
G : Type u_3
inst✝¹ : Group G
inst✝ : MulAction G E
hf : IsQuotientCoveringMap f G
x : X
e e' : ↑(f ⁻¹' {x})
⊢ False

Response:
by
  letI := hf.mulActionFiber x
  have := hf.mulActionFiber_isPretransitive x
  obtain ⟨g, rfl⟩ := MulAction.IsPretransitive.exists_smul_eq e e' (M := G)
  use g
  ext
  simp

[User]
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.GroupTheory.Coset.Defs
public import Mathlib.Topology.Algebra.ConstMulAction
public import Mathlib.Topology.Algebra.Group.Quotient
public import Mathlib.Topology.Covering.Basic

Namespace:
IsQuotientCoveringMap

Local safe context:
/-
Copyright (c) 2025 Junyan Xu. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Junyan Xu
-/
/-!
# Covering maps to quotients by free and properly discontinuous group actions
-/

@[expose] public section

variable {E X : Type*} [TopologicalSpace E] [TopologicalSpace X] (f : E → X)
variable (G : Type*) [Group G] [MulAction G E]

open Topology

/-- A function from a topological space `E` with an action by a discrete group to another
topological space `X` is a quotient covering map if it is a quotient map, the action is
continuous and transitive on fibers, and every point of `E` has a neighborhood whose translates
by the group elements are pairwise disjoint. -/
structure IsAddQuotientCoveringMap (G) [AddGroup G] [AddAction G E] : Prop
    extends IsQuotientMap f, ContinuousConstVAdd G E where
  apply_eq_iff_mem_orbit {e₁ e₂} : f e₁ = f e₂ ↔ e₁ ∈ AddAction.orbit G e₂
  disjoint (e : E) : ∃ U ∈ 𝓝 e, ∀ g : G, ((g +ᵥ ·) '' U ∩ U).Nonempty → g = 0

/-- A function from a topological space `E` with an action by a discrete group to another
topological space `X` is a quotient covering map if it is a quotient map, the action is
continuous and transitive on fibers, and every point of `E` has a neighborhood whose translates
by the group elements are pairwise disjoint. -/
@[mk_iff, to_additive]
structure IsQuotientCoveringMap : Prop extends IsQuotientMap f, ContinuousConstSMul G E where
  apply_eq_iff_mem_orbit {e₁ e₂} : f e₁ = f e₂ ↔ e₁ ∈ MulAction.orbit G e₂
  disjoint (e : E) : ∃ U ∈ 𝓝 e, ∀ g : G, ((g • ·) '' U ∩ U).Nonempty → g = 1

attribute [to_additive] isQuotientCoveringMap_iff

namespace IsQuotientCoveringMap

@[to_additive] theorem subgroup_congr (S S' : Subgroup G) (eq : S = S') :
    IsQuotientCoveringMap f S ↔ IsQuotientCoveringMap f S' := by rw [eq]

variable {f G} (hf : IsQuotientCoveringMap f G)
include hf

@[to_additive] protected theorem map_smul (g : G) {e : E} : f (g • e) = f e :=
  hf.apply_eq_iff_mem_orbit.mpr ⟨g, rfl⟩

/-- The group action on the domain of a quotient covering map is free. -/
@[to_additive] theorem isCancelSMul : IsCancelSMul G E where
  right_cancel' g g' e eq := by
    have ⟨U, heU, hU⟩ := hf.disjoint e
    simpa [inv_mul_eq_one, eq_comm] using hU (g'⁻¹ * g)
      ⟨e, ⟨e, mem_of_mem_nhds heU, by simpa [mul_smul, inv_smul_eq_iff]⟩, mem_of_mem_nhds heU⟩

@[to_additive] theorem homeomorph_comp {Y} [TopologicalSpace Y]
    (φ : X ≃ₜ Y) : IsQuotientCoveringMap (φ ∘ f) G where
  __ := φ.isQuotientMap.comp hf.toIsQuotientMap
  continuous_const_smul := hf.continuous_const_smul
  apply_eq_iff_mem_orbit := by simpa using @hf.apply_eq_iff_mem_orbit
  disjoint := hf.disjoint

omit hf in
@[to_additive (attr := simp)] theorem homeomorph_comp_iff {Y} [TopologicalSpace Y]
    (φ : X ≃ₜ Y) : IsQuotientCoveringMap (φ ∘ f) G ↔ IsQuotientCoveringMap f G where
  mp h := by convert! h.homeomorph_comp φ.symm; ext; simp
  mpr h := h.homeomorph_comp φ

/-- Fibers of a quotient covering map by a group G is a G-torsor. -/
@[to_additive /-- Fibers of a quotient covering map by an additive group G is a G-torsor. -/]
noncomputable def fiberEquivGroup {x : X} (e : f ⁻¹' {x}) : f ⁻¹' {x} ≃ G :=
  have := hf.isCancelSMul
  .symm <| .ofBijective (fun g ↦ ⟨g • e, (hf.map_smul g).trans e.2⟩)
    ⟨fun _ _ eq ↦ IsCancelSMul.right_cancel _ _ e.1 congr($eq), fun e' ↦
      have ⟨g, eq⟩ := hf.apply_eq_iff_mem_orbit.mp (e'.2.trans e.2.symm); ⟨g, Subtype.ext eq⟩⟩

@[simp] theorem fiberEquivGroup_self {x : X} (e : f ⁻¹' {x}) : hf.fiberEquivGroup e e = 1 :=
  (Equiv.apply_eq_iff_eq_symm_apply _).mpr <| Subtype.ext (one_smul ..).symm

@[simp] theorem fiberEquivGroup_eq_iff {x : X} (e e' : f ⁻¹' {x}) (g : G) :
    hf.fiberEquivGroup e e' = g ↔ e' = g • (e : E) := by
  rw [fiberEquivGroup, Equiv.symm_apply_eq, Equiv.ofBijective_apply, Subtype.mk.injEq]

@[simp] theorem fiberEquivGroup_smul_self {x : X} (e : f ⁻¹' {x}) {e' : f ⁻¹' {x}} :
    hf.fiberEquivGroup e e' • (e : E) = (e' : E) :=
  congr($((hf.fiberEquivGroup e).symm_apply_apply e'))

/-- The action of `G` restricted to the fiber. -/
@[implicit_reducible] def mulActionFiber (x : X) : MulAction G (f ⁻¹' {x}) :=
  SubMulAction.mulAction ⟨f ⁻¹' {x}, fun g _ h ↦ (hf.map_smul g).trans h⟩

@[simp] lemma coe_mulActionFiber_smul (x : X) (g : G) (e : f ⁻¹' {x}) :
    letI := hf.mulActionFiber x
    (↑(g • e) : E) = g • (e : E) :=
  rfl

lemma mulActionFiber_isPretransitive (x : X) :
    letI := hf.mulActionFiber x
    MulAction.IsPretransitive G (f ⁻¹' {x}) := by
  letI := hf.mulActionFiber x
  constructor
  intro e e'
  obtain ⟨g, hg⟩ := hf.apply_eq_iff_mem_orbit.mp (e'.2.trans e.2.symm)
  exact ⟨g, Subtype.ext hg⟩

/-- A quotient covering map `f` induces a permutation action on each fiber. -/
@[simps!] def toPermFiber (x : X) : G →* Equiv.Perm (f ⁻¹' {x}) :=
  (hf.mulActionFiber x).toPermHom

theorem toPermFiber_ext (x : X) (e : f ⁻¹' {x}) {g g' : G}
    (eq : hf.toPermFiber x g e = hf.toPermFiber x g' e) : g = g' :=
  have := hf.isCancelSMul
  IsCancelSMul.right_cancel _ _ e.1 congr($eq)

theorem toPermFiber_injective (x : X) : Function.Injective (hf.toPermFiber x) :=
  have ⟨e, he⟩ := hf.surjective x
  fun _ _ eq ↦ hf.toPermFiber_ext x ⟨e, he⟩ congr($eq _)

Target:
theorem exists_toPermFiber_eq {x : X} (e e' : f ⁻¹' {x}) : ∃ g, hf.toPermFiber x g e = e' :=

Failed candidate:
by
  have __repair_plan_d4fa0bf252 : False := by
    skip
  letI := hf.mulActionFiber x
  have := hf.mulActionFiber_isPretransitive x
  obtain ⟨g, rfl⟩ := MulAction.IsPretransitive.exists_smul_eq e e' (M := G)
  use g
  ext
  simp

Structured Lean error:
{"kind": "unsolved_goals_multistep_planning", "message": "<LEAN_FILE>:127:43: error: unsolved goals\nE : Type u_1\nX : Type u_2\ninst✝³ : TopologicalSpace E\ninst✝² : TopologicalSpace X\nf : E → X\nG : Type u_3\ninst✝¹ : Group G\ninst✝ : MulAction G E\nhf : IsQuotientCoveringMap f G\nx : X\ne e' : ↑(f ⁻¹' {x})\n⊢ False", "returncode": 1}

Corrected proof:

[Assistant]
by
  letI := hf.mulActionFiber x
  have := hf.mulActionFiber_isPretransitive x
  obtain ⟨g, rfl⟩ := MulAction.IsPretransitive.exists_smul_eq e e' (M := G)
  use g
  ext
  simp

Prompt:
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.GroupTheory.Coset.Defs
public import Mathlib.Topology.Algebra.ConstMulAction
public import Mathlib.Topology.Algebra.Group.Quotient
public import Mathlib.Topology.Covering.Basic

Namespace:
IsQuotientCoveringMap

Local safe context:
/-
Copyright (c) 2025 Junyan Xu. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Junyan Xu
-/
/-!
# Covering maps to quotients by free and properly discontinuous group actions
-/

@[expose] public section

variable {E X : Type*} [TopologicalSpace E] [TopologicalSpace X] (f : E → X)
variable (G : Type*) [Group G] [MulAction G E]

open Topology

/-- A function from a topological space `E` with an action by a discrete group to another
topological space `X` is a quotient covering map if it is a quotient map, the action is
continuous and transitive on fibers, and every point of `E` has a neighborhood whose translates
by the group elements are pairwise disjoint. -/
structure IsAddQuotientCoveringMap (G) [AddGroup G] [AddAction G E] : Prop
    extends IsQuotientMap f, ContinuousConstVAdd G E where
  apply_eq_iff_mem_orbit {e₁ e₂} : f e₁ = f e₂ ↔ e₁ ∈ AddAction.orbit G e₂
  disjoint (e : E) : ∃ U ∈ 𝓝 e, ∀ g : G, ((g +ᵥ ·) '' U ∩ U).Nonempty → g = 0

/-- A function from a topological space `E` with an action by a discrete group to another
topological space `X` is a quotient covering map if it is a quotient map, the action is
continuous and transitive on fibers, and every point of `E` has a neighborhood whose translates
by the group elements are pairwise disjoint. -/
@[mk_iff, to_additive]
structure IsQuotientCoveringMap : Prop extends IsQuotientMap f, ContinuousConstSMul G E where
  apply_eq_iff_mem_orbit {e₁ e₂} : f e₁ = f e₂ ↔ e₁ ∈ MulAction.orbit G e₂
  disjoint (e : E) : ∃ U ∈ 𝓝 e, ∀ g : G, ((g • ·) '' U ∩ U).Nonempty → g = 1

attribute [to_additive] isQuotientCoveringMap_iff

namespace IsQuotientCoveringMap

@[to_additive] theorem subgroup_congr (S S' : Subgroup G) (eq : S = S') :
    IsQuotientCoveringMap f S ↔ IsQuotientCoveringMap f S' := by rw [eq]

variable {f G} (hf : IsQuotientCoveringMap f G)
include hf

@[to_additive] protected theorem map_smul (g : G) {e : E} : f (g • e) = f e :=
  hf.apply_eq_iff_mem_orbit.mpr ⟨g, rfl⟩

/-- The group action on the domain of a quotient covering map is free. -/
@[to_additive] theorem isCancelSMul : IsCancelSMul G E where
  right_cancel' g g' e eq := by
    have ⟨U, heU, hU⟩ := hf.disjoint e
    simpa [inv_mul_eq_one, eq_comm] using hU (g'⁻¹ * g)
      ⟨e, ⟨e, mem_of_mem_nhds heU, by simpa [mul_smul, inv_smul_eq_iff]⟩, mem_of_mem_nhds heU⟩

@[to_additive] theorem homeomorph_comp {Y} [TopologicalSpace Y]
    (φ : X ≃ₜ Y) : IsQuotientCoveringMap (φ ∘ f) G where
  __ := φ.isQuotientMap.comp hf.toIsQuotientMap
  continuous_const_smul := hf.continuous_const_smul
  apply_eq_iff_mem_orbit := by simpa using @hf.apply_eq_iff_mem_orbit
  disjoint := hf.disjoint

omit hf in
@[to_additive (attr := simp)] theorem homeomorph_comp_iff {Y} [TopologicalSpace Y]
    (φ : X ≃ₜ Y) : IsQuotientCoveringMap (φ ∘ f) G ↔ IsQuotientCoveringMap f G where
  mp h := by convert! h.homeomorph_comp φ.symm; ext; simp
  mpr h := h.homeomorph_comp φ

/-- Fibers of a quotient covering map by a group G is a G-torsor. -/
@[to_additive /-- Fibers of a quotient covering map by an additive group G is a G-torsor. -/]
noncomputable def fiberEquivGroup {x : X} (e : f ⁻¹' {x}) : f ⁻¹' {x} ≃ G :=
  have := hf.isCancelSMul
  .symm <| .ofBijective (fun g ↦ ⟨g • e, (hf.map_smul g).trans e.2⟩)
    ⟨fun _ _ eq ↦ IsCancelSMul.right_cancel _ _ e.1 congr($eq), fun e' ↦
      have ⟨g, eq⟩ := hf.apply_eq_iff_mem_orbit.mp (e'.2.trans e.2.symm); ⟨g, Subtype.ext eq⟩⟩

@[simp] theorem fiberEquivGroup_self {x : X} (e : f ⁻¹' {x}) : hf.fiberEquivGroup e e = 1 :=
  (Equiv.apply_eq_iff_eq_symm_apply _).mpr <| Subtype.ext (one_smul ..).symm

@[simp] theorem fiberEquivGroup_eq_iff {x : X} (e e' : f ⁻¹' {x}) (g : G) :
    hf.fiberEquivGroup e e' = g ↔ e' = g • (e : E) := by
  rw [fiberEquivGroup, Equiv.symm_apply_eq, Equiv.ofBijective_apply, Subtype.mk.injEq]

@[simp] theorem fiberEquivGroup_smul_self {x : X} (e : f ⁻¹' {x}) {e' : f ⁻¹' {x}} :
    hf.fiberEquivGroup e e' • (e : E) = (e' : E) :=
  congr($((hf.fiberEquivGroup e).symm_apply_apply e'))

/-- The action of `G` restricted to the fiber. -/
@[implicit_reducible] def mulActionFiber (x : X) : MulAction G (f ⁻¹' {x}) :=
  SubMulAction.mulAction ⟨f ⁻¹' {x}, fun g _ h ↦ (hf.map_smul g).trans h⟩

@[simp] lemma coe_mulActionFiber_smul (x : X) (g : G) (e : f ⁻¹' {x}) :
    letI := hf.mulActionFiber x
    (↑(g • e) : E) = g • (e : E) :=
  rfl

lemma mulActionFiber_isPretransitive (x : X) :
    letI := hf.mulActionFiber x
    MulAction.IsPretransitive G (f ⁻¹' {x}) := by
  letI := hf.mulActionFiber x
  constructor
  intro e e'
  obtain ⟨g, hg⟩ := hf.apply_eq_iff_mem_orbit.mp (e'.2.trans e.2.symm)
  exact ⟨g, Subtype.ext hg⟩

/-- A quotient covering map `f` induces a permutation action on each fiber. -/
@[simps!] def toPermFiber (x : X) : G →* Equiv.Perm (f ⁻¹' {x}) :=
  (hf.mulActionFiber x).toPermHom

theorem toPermFiber_ext (x : X) (e : f ⁻¹' {x}) {g g' : G}
    (eq : hf.toPermFiber x g e = hf.toPermFiber x g' e) : g = g' :=
  have := hf.isCancelSMul
  IsCancelSMul.right_cancel _ _ e.1 congr($eq)

theorem toPermFiber_injective (x : X) : Function.Injective (hf.toPermFiber x) :=
  have ⟨e, he⟩ := hf.surjective x
  fun _ _ eq ↦ hf.toPermFiber_ext x ⟨e, he⟩ congr($eq _)

Target:
theorem exists_toPermFiber_eq {x : X} (e e' : f ⁻¹' {x}) : ∃ g, hf.toPermFiber x g e = e' :=

Failed candidate:
by
  have __repair_plan_d4fa0bf252 : False := by
    skip
  letI := hf.mulActionFiber x
  have := hf.mulActionFiber_isPretransitive x
  obtain ⟨g, rfl⟩ := MulAction.IsPretransitive.exists_smul_eq e e' (M := G)
  use g
  ext
  simp

Structured Lean error:
{"kind": "unsolved_goals_multistep_planning", "message": "<LEAN_FILE>:127:43: error: unsolved goals\nE : Type u_1\nX : Type u_2\ninst✝³ : TopologicalSpace E\ninst✝² : TopologicalSpace X\nf : E → X\nG : Type u_3\ninst✝¹ : Group G\ninst✝ : MulAction G E\nhf : IsQuotientCoveringMap f G\nx : X\ne e' : ↑(f ⁻¹' {x})\n⊢ False", "returncode": 1}

Corrected proof:


Response:
by
  let b := chooseBasis R M₁
  rw [← LinearMap.charpoly_toMatrix φ b, ← LinearMap.charpoly_toMatrix (e.conj φ) (b.map e)]
  congr 1
  ext i j : 1
  simp [LinearMap.toMatrix]

[User]
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.LinearAlgebra.Charpoly.Basic
public import Mathlib.LinearAlgebra.Matrix.Basis
public import Mathlib.RingTheory.Finiteness.Prod

Namespace:
(root)

Local context:
/-
Copyright (c) 2021 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Riccardo Brasca
-/
/-!

# Characteristic polynomial

## Main result

* `LinearMap.charpoly_toMatrix f` : `charpoly f` is the characteristic polynomial of the matrix
  of `f` in any basis.

-/

public section

noncomputable section

open Module Free Polynomial Matrix

universe u v w

variable {R M M₁ M₂ : Type*} [CommRing R]
variable [AddCommGroup M] [Module R M] [Module.Free R M] [Module.Finite R M]
variable [AddCommGroup M₁] [Module R M₁] [Module.Finite R M₁] [Module.Free R M₁]
variable [AddCommGroup M₂] [Module R M₂] [Module.Finite R M₂] [Module.Free R M₂]
variable (f : M →ₗ[R] M)

namespace LinearMap

section Basic

/-- `charpoly f` is the characteristic polynomial of the matrix of `f` in any basis. -/
@[simp]
theorem charpoly_toMatrix {ι : Type w} [DecidableEq ι] [Fintype ι] (b : Basis ι R M) :
    (toMatrix b b f).charpoly = f.charpoly := by
  nontriviality R
  unfold LinearMap.charpoly
  set b' := chooseBasis R M
  rw [← basis_toMatrix_mul_linearMap_toMatrix_mul_basis_toMatrix b b' b b']
  set P := b.toMatrix b'
  set A := toMatrix b' b' f
  set Q := b'.toMatrix b
  let e := Basis.indexEquiv b b'
  let ι' := ChooseBasisIndex R M
  let φ := reindexLinearEquiv R R e e
  let φ₁ := reindexLinearEquiv R R e (Equiv.refl ι')
  let φ₂ := reindexLinearEquiv R R (Equiv.refl ι') (Equiv.refl ι')
  let φ₃ := reindexLinearEquiv R R (Equiv.refl ι') e
  calc
    (P * A * Q).charpoly = (φ (P * A * Q)).charpoly := (charpoly_reindex ..).symm
    _ = (φ₁ P * φ₂ A * φ₃ Q).charpoly := by rw [reindexLinearEquiv_mul, reindexLinearEquiv_mul]
    _ = A.charpoly := by rw [charpoly_mul_comm, ← mul_assoc]; simp [P, Q, φ₁, φ₂, φ₃]

lemma charpoly_prodMap (f₁ : M₁ →ₗ[R] M₁) (f₂ : M₂ →ₗ[R] M₂) :
    (f₁.prodMap f₂).charpoly = f₁.charpoly * f₂.charpoly := by
  let b₁ := chooseBasis R M₁
  let b₂ := chooseBasis R M₂
  let b := b₁.prod b₂
  rw [← charpoly_toMatrix f₁ b₁, ← charpoly_toMatrix f₂ b₂, ← charpoly_toMatrix (f₁.prodMap f₂) b,
    toMatrix_prodMap b₁ b₂ f₁ f₂, Matrix.charpoly_fromBlocks_zero₁₂]

end Basic

end LinearMap

@[simp]

Target:
lemma LinearEquiv.charpoly_conj (e : M₁ ≃ₗ[R] M₂) (φ : Module.End R M₁) :
    (e.conj φ).charpoly = φ.charpoly :=

Proof body:

[Assistant]
by
  let b := chooseBasis R M₁
  rw [← LinearMap.charpoly_toMatrix φ b, ← LinearMap.charpoly_toMatrix (e.conj φ) (b.map e)]
  congr 1
  ext i j : 1
  simp [LinearMap.toMatrix]

Prompt:
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.LinearAlgebra.Charpoly.Basic
public import Mathlib.LinearAlgebra.Matrix.Basis
public import Mathlib.RingTheory.Finiteness.Prod

Namespace:
(root)

Local context:
/-
Copyright (c) 2021 Riccardo Brasca. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Riccardo Brasca
-/
/-!

# Characteristic polynomial

## Main result

* `LinearMap.charpoly_toMatrix f` : `charpoly f` is the characteristic polynomial of the matrix
  of `f` in any basis.

-/

public section

noncomputable section

open Module Free Polynomial Matrix

universe u v w

variable {R M M₁ M₂ : Type*} [CommRing R]
variable [AddCommGroup M] [Module R M] [Module.Free R M] [Module.Finite R M]
variable [AddCommGroup M₁] [Module R M₁] [Module.Finite R M₁] [Module.Free R M₁]
variable [AddCommGroup M₂] [Module R M₂] [Module.Finite R M₂] [Module.Free R M₂]
variable (f : M →ₗ[R] M)

namespace LinearMap

section Basic

/-- `charpoly f` is the characteristic polynomial of the matrix of `f` in any basis. -/
@[simp]
theorem charpoly_toMatrix {ι : Type w} [DecidableEq ι] [Fintype ι] (b : Basis ι R M) :
    (toMatrix b b f).charpoly = f.charpoly := by
  nontriviality R
  unfold LinearMap.charpoly
  set b' := chooseBasis R M
  rw [← basis_toMatrix_mul_linearMap_toMatrix_mul_basis_toMatrix b b' b b']
  set P := b.toMatrix b'
  set A := toMatrix b' b' f
  set Q := b'.toMatrix b
  let e := Basis.indexEquiv b b'
  let ι' := ChooseBasisIndex R M
  let φ := reindexLinearEquiv R R e e
  let φ₁ := reindexLinearEquiv R R e (Equiv.refl ι')
  let φ₂ := reindexLinearEquiv R R (Equiv.refl ι') (Equiv.refl ι')
  let φ₃ := reindexLinearEquiv R R (Equiv.refl ι') e
  calc
    (P * A * Q).charpoly = (φ (P * A * Q)).charpoly := (charpoly_reindex ..).symm
    _ = (φ₁ P * φ₂ A * φ₃ Q).charpoly := by rw [reindexLinearEquiv_mul, reindexLinearEquiv_mul]
    _ = A.charpoly := by rw [charpoly_mul_comm, ← mul_assoc]; simp [P, Q, φ₁, φ₂, φ₃]

lemma charpoly_prodMap (f₁ : M₁ →ₗ[R] M₁) (f₂ : M₂ →ₗ[R] M₂) :
    (f₁.prodMap f₂).charpoly = f₁.charpoly * f₂.charpoly := by
  let b₁ := chooseBasis R M₁
  let b₂ := chooseBasis R M₂
  let b := b₁.prod b₂
  rw [← charpoly_toMatrix f₁ b₁, ← charpoly_toMatrix f₂ b₂, ← charpoly_toMatrix (f₁.prodMap f₂) b,
    toMatrix_prodMap b₁ b₂ f₁ f₂, Matrix.charpoly_fromBlocks_zero₁₂]

end Basic

end LinearMap

@[simp]

Target:
lemma LinearEquiv.charpoly_conj (e : M₁ ≃ₗ[R] M₂) (φ : Module.End R M₁) :
    (e.conj φ).charpoly = φ.charpoly :=

Proof body:


<LEAN_FILE>:71:2: warning: declaration uses `sorry`
<LEAN_FILE>:103:35: error(lean.unknownIdentifier): Unknown identifier `__oprover_overlong_8039334af5`
<LEAN_FILE>:78:0: error: unsolved goals
M : Type u_1
α : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : Monoid M
inst✝ : MulAction M α
⊢ IsTopologicallyTransitive M α ↔ ∀ {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m, (fun x => m • x) ⁻¹' U)

Response:
by
  simp only [dense_iff_inter_open, inter_iUnion, nonempty_iUnion, ← image_inter_nonempty_iff]
  exact ⟨fun h _ h₁ h₂ _ h₃ h₄ ↦ h.1 h₃ h₄ h₁ h₂, fun h ↦ ⟨fun h₁ h₂ h₃ h₄ ↦ h h₃ h₄ _ h₁ h₂⟩⟩

[User]
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Dynamics.Minimal

Namespace:
(root)

Local safe context:
/-
Copyright (c) 2025 Daniel Figueroa. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Daniel Figueroa
-/
/-!
# Topologically transitive monoid actions

In this file we define an action of a monoid `M` on a topological space `α` to be
*topologically transitive* if for any pair of nonempty open sets `U` and `V` in `α` there exists an
`m : M` such that `(m • U) ∩ V` is nonempty. We also provide an additive version of this definition
and prove basic facts about topologically transitive actions.

## Tags

group action, topologically transitive
-/

public section

open scoped Pointwise

/-- An action of an additive monoid `M` on a topological space `α` is called
*topologically transitive* if for any pair of nonempty open sets `U` and `V` in `α` there exists an
`m : M` such that `(m +ᵥ U) ∩ V` is nonempty. -/
class AddAction.IsTopologicallyTransitive (M α : Type*) [AddMonoid M] [TopologicalSpace α]
    [AddAction M α] : Prop where
  exists_vadd_inter : ∀ {U V : Set α}, IsOpen U → U.Nonempty → IsOpen V → V.Nonempty →
    ∃ m : M, ((m +ᵥ U) ∩ V).Nonempty

/-- An action of a monoid `M` on a topological space `α` is called *topologically transitive* if for
any pair of nonempty open sets `U` and `V` in `α` there exists an `m : M` such that `(m • U) ∩ V` is
nonempty. -/
@[to_additive]
class MulAction.IsTopologicallyTransitive (M α : Type*) [Monoid M] [TopologicalSpace α]
    [MulAction M α] : Prop where
  exists_smul_inter : ∀ {U V : Set α}, IsOpen U → U.Nonempty → IsOpen V → V.Nonempty →
    ∃ m : M, ((m • U) ∩ V).Nonempty

open MulAction Set

variable (M : Type*) {α : Type*} [TopologicalSpace α] [Monoid M] [MulAction M α]

section IsTopologicallyTransitive

@[to_additive]
theorem MulAction.isTopologicallyTransitive_iff :
    IsTopologicallyTransitive M α ↔ ∀ {U V : Set α}, IsOpen U → U.Nonempty → IsOpen V →
    V.Nonempty → ∃ m : M, ((m • U) ∩ V).Nonempty := ⟨fun h ↦ h.1, fun h ↦ ⟨h⟩⟩

/-- An action of a monoid `M` on `α` is topologically transitive if and only if for any nonempty
open subset `U` of `α` the union over the elements of `M` of images of `U` is dense in `α`. -/
@[to_additive /-- An action of an additive monoid `M` on `α` is topologically transitive if and only
if for any nonempty open subset `U` of `α` the union over the elements of `M` of images of `U` is
dense in `α`. -/]
theorem MulAction.isTopologicallyTransitive_iff_dense_iUnion :
    IsTopologicallyTransitive M α ↔
    ∀ {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m : M, m • U) := by
  simp only [isTopologicallyTransitive_iff, inter_comm, dense_iff_inter_open, inter_iUnion,
    nonempty_iUnion]
  exact ⟨fun h _ h₁ h₂ _ h₃ h₄ ↦ h h₁ h₂ h₃ h₄, fun h _ _ h₁ h₂ h₃ h₄ ↦ h h₁ h₂ _ h₃ h₄⟩

/-- An action of a monoid `M` on `α` is topologically transitive if and only if for any nonempty
open subset `U` of `α` the union of the preimages of `U` over the elements of `M` is dense in `α`.
-/
@[to_additive /-- An action of an additive monoid `M` on `α` is topologically transitive if and only
if for any nonempty open subset `U` of `α` the union of the preimages of `U` over the elements of
`M` is dense in `α`. -/]

Target:
theorem MulAction.isTopologicallyTransitive_iff_dense_iUnion_preimage :
    IsTopologicallyTransitive M α ↔
    ∀ {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m : M, (m • ·) ⁻¹' U) :=

Failed candidate:
by
  have __repair_pad_0_8039334af5 : True := by trivial
  have __repair_pad_1_8039334af5 : True := by trivial
  have __repair_pad_2_8039334af5 : True := by trivial
  have __repair_pad_3_8039334af5 : True := by trivial
  have __repair_pad_4_8039334af5 : True := by trivial
  have __repair_pad_5_8039334af5 : True := by trivial
  have __repair_pad_6_8039334af5 : True := by trivial
  have __repair_pad_7_8039334af5 : True := by trivial
  have __repair_pad_8_8039334af5 : True := by trivial
  have __repair_pad_9_8039334af5 : True := by trivial
  have __repair_pad_10_8039334af5 : True := by trivial
  have __repair_pad_11_8039334af5 : True := by trivial
  have __repair_pad_12_8039334af5 : True := by trivial
  have __repair_pad_13_8039334af5 : True := by trivial
  have __repair_pad_14_8039334af5 : True := by trivial
  have __repair_pad_15_8039334af5 : True := by trivial
  have __repair_pad_16_8039334af5 : True := by trivial
  have __repair_pad_17_8039334af5 : True := by trivial
  have __repair_pad_18_8039334af5 : True := by trivial
  have __repair_pad_19_8039334af5 : True := by trivial
  have __repair_pad_20_8039334af5 : True := by trivial
  have __repair_pad_21_8039334af5 : True := by trivial
  have __repair_pad_22_8039334af5 : True := by trivial
  have __repair_pad_23_8039334af5 : True := by trivial
  have __repair_fail_8039334af5 := __oprover_overlong_8039334af5
  simp only [dense_iff_inter_open, inter_iUnion, nonempty_iUnion, ← image_inter_nonempty_iff]
  exact ⟨fun h _ h₁ h₂ _ h₃ h₄ ↦ h.1 h₃ h₄ h₁ h₂, fun h ↦ ⟨fun h₁ h₂ h₃ h₄ ↦ h h₃ h₄ _ h₁ h₂⟩⟩

Structured Lean error:
{"kind": "unknown_identifier_namespace_import", "message": "<LEAN_FILE>:71:2: warning: declaration uses `sorry`\n<LEAN_FILE>:103:35: error(lean.unknownIdentifier): Unknown identifier `__oprover_overlong_8039334af5`\n<LEAN_FILE>:78:0: error: unsolved goals\nM : Type u_1\nα : Type u_2\ninst✝² : TopologicalSpace α\ninst✝¹ : Monoid M\ninst✝ : MulAction M α\n⊢ IsTopologicallyTransitive M α ↔ ∀ {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m, (fun x => m • x) ⁻¹' U)", "returncode": 1}

Corrected proof:

[Assistant]
by
  simp only [dense_iff_inter_open, inter_iUnion, nonempty_iUnion, ← image_inter_nonempty_iff]
  exact ⟨fun h _ h₁ h₂ _ h₃ h₄ ↦ h.1 h₃ h₄ h₁ h₂, fun h ↦ ⟨fun h₁ h₂ h₃ h₄ ↦ h h₃ h₄ _ h₁ h₂⟩⟩

Prompt:
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Dynamics.Minimal

Namespace:
(root)

Local safe context:
/-
Copyright (c) 2025 Daniel Figueroa. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Daniel Figueroa
-/
/-!
# Topologically transitive monoid actions

In this file we define an action of a monoid `M` on a topological space `α` to be
*topologically transitive* if for any pair of nonempty open sets `U` and `V` in `α` there exists an
`m : M` such that `(m • U) ∩ V` is nonempty. We also provide an additive version of this definition
and prove basic facts about topologically transitive actions.

## Tags

group action, topologically transitive
-/

public section

open scoped Pointwise

/-- An action of an additive monoid `M` on a topological space `α` is called
*topologically transitive* if for any pair of nonempty open sets `U` and `V` in `α` there exists an
`m : M` such that `(m +ᵥ U) ∩ V` is nonempty. -/
class AddAction.IsTopologicallyTransitive (M α : Type*) [AddMonoid M] [TopologicalSpace α]
    [AddAction M α] : Prop where
  exists_vadd_inter : ∀ {U V : Set α}, IsOpen U → U.Nonempty → IsOpen V → V.Nonempty →
    ∃ m : M, ((m +ᵥ U) ∩ V).Nonempty

/-- An action of a monoid `M` on a topological space `α` is called *topologically transitive* if for
any pair of nonempty open sets `U` and `V` in `α` there exists an `m : M` such that `(m • U) ∩ V` is
nonempty. -/
@[to_additive]
class MulAction.IsTopologicallyTransitive (M α : Type*) [Monoid M] [TopologicalSpace α]
    [MulAction M α] : Prop where
  exists_smul_inter : ∀ {U V : Set α}, IsOpen U → U.Nonempty → IsOpen V → V.Nonempty →
    ∃ m : M, ((m • U) ∩ V).Nonempty

open MulAction Set

variable (M : Type*) {α : Type*} [TopologicalSpace α] [Monoid M] [MulAction M α]

section IsTopologicallyTransitive

@[to_additive]
theorem MulAction.isTopologicallyTransitive_iff :
    IsTopologicallyTransitive M α ↔ ∀ {U V : Set α}, IsOpen U → U.Nonempty → IsOpen V →
    V.Nonempty → ∃ m : M, ((m • U) ∩ V).Nonempty := ⟨fun h ↦ h.1, fun h ↦ ⟨h⟩⟩

/-- An action of a monoid `M` on `α` is topologically transitive if and only if for any nonempty
open subset `U` of `α` the union over the elements of `M` of images of `U` is dense in `α`. -/
@[to_additive /-- An action of an additive monoid `M` on `α` is topologically transitive if and only
if for any nonempty open subset `U` of `α` the union over the elements of `M` of images of `U` is
dense in `α`. -/]
theorem MulAction.isTopologicallyTransitive_iff_dense_iUnion :
    IsTopologicallyTransitive M α ↔
    ∀ {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m : M, m • U) := by
  simp only [isTopologicallyTransitive_iff, inter_comm, dense_iff_inter_open, inter_iUnion,
    nonempty_iUnion]
  exact ⟨fun h _ h₁ h₂ _ h₃ h₄ ↦ h h₁ h₂ h₃ h₄, fun h _ _ h₁ h₂ h₃ h₄ ↦ h h₁ h₂ _ h₃ h₄⟩

/-- An action of a monoid `M` on `α` is topologically transitive if and only if for any nonempty
open subset `U` of `α` the union of the preimages of `U` over the elements of `M` is dense in `α`.
-/
@[to_additive /-- An action of an additive monoid `M` on `α` is topologically transitive if and only
if for any nonempty open subset `U` of `α` the union of the preimages of `U` over the elements of
`M` is dense in `α`. -/]

Target:
theorem MulAction.isTopologicallyTransitive_iff_dense_iUnion_preimage :
    IsTopologicallyTransitive M α ↔
    ∀ {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m : M, (m • ·) ⁻¹' U) :=

Failed candidate:
by
  have __repair_pad_0_8039334af5 : True := by trivial
  have __repair_pad_1_8039334af5 : True := by trivial
  have __repair_pad_2_8039334af5 : True := by trivial
  have __repair_pad_3_8039334af5 : True := by trivial
  have __repair_pad_4_8039334af5 : True := by trivial
  have __repair_pad_5_8039334af5 : True := by trivial
  have __repair_pad_6_8039334af5 : True := by trivial
  have __repair_pad_7_8039334af5 : True := by trivial
  have __repair_pad_8_8039334af5 : True := by trivial
  have __repair_pad_9_8039334af5 : True := by trivial
  have __repair_pad_10_8039334af5 : True := by trivial
  have __repair_pad_11_8039334af5 : True := by trivial
  have __repair_pad_12_8039334af5 : True := by trivial
  have __repair_pad_13_8039334af5 : True := by trivial
  have __repair_pad_14_8039334af5 : True := by trivial
  have __repair_pad_15_8039334af5 : True := by trivial
  have __repair_pad_16_8039334af5 : True := by trivial
  have __repair_pad_17_8039334af5 : True := by trivial
  have __repair_pad_18_8039334af5 : True := by trivial
  have __repair_pad_19_8039334af5 : True := by trivial
  have __repair_pad_20_8039334af5 : True := by trivial
  have __repair_pad_21_8039334af5 : True := by trivial
  have __repair_pad_22_8039334af5 : True := by trivial
  have __repair_pad_23_8039334af5 : True := by trivial
  have __repair_fail_8039334af5 := __oprover_overlong_8039334af5
  simp only [dense_iff_inter_open, inter_iUnion, nonempty_iUnion, ← image_inter_nonempty_iff]
  exact ⟨fun h _ h₁ h₂ _ h₃ h₄ ↦ h.1 h₃ h₄ h₁ h₂, fun h ↦ ⟨fun h₁ h₂ h₃ h₄ ↦ h h₃ h₄ _ h₁ h₂⟩⟩

Structured Lean error:
{"kind": "unknown_identifier_namespace_import", "message": "<LEAN_FILE>:71:2: warning: declaration uses `sorry`\n<LEAN_FILE>:103:35: error(lean.unknownIdentifier): Unknown identifier `__oprover_overlong_8039334af5`\n<LEAN_FILE>:78:0: error: unsolved goals\nM : Type u_1\nα : Type u_2\ninst✝² : TopologicalSpace α\ninst✝¹ : Monoid M\ninst✝ : MulAction M α\n⊢ IsTopologicallyTransitive M α ↔ ∀ {U : Set α}, IsOpen U → U.Nonempty → Dense (⋃ m, (fun x => m • x) ⁻¹' U)", "returncode": 1}

Corrected proof:


<LEAN_FILE>:43:38: error: Type mismatch
  True.intro
has type
  True
but is expected to have type
  False

Response:
by
  have : Module.Finite P.Ring P.Cotangent :=
    have : Module.Finite P.Ring P.ker := .of_fg h'
    .of_surjective _ Extension.Cotangent.mk_surjective
  have : Module.Finite S P.Cotangent := Module.Finite.of_restrictScalars_finite P.Ring _ _
  rw [← IsLocalRing.split_injective_iff_lTensor_residueField_injective,
    P.formallySmooth_iff_split_injection]

[User]
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.RingTheory.Flat.FaithfullyFlat.Basic
public import Mathlib.RingTheory.LocalRing.Module
public import Mathlib.RingTheory.Smooth.Basic
public import Mathlib.RingTheory.TensorProduct.Free

Namespace:
Algebra

Local safe context:
/-
Copyright (c) 2024 Andrew Yang. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Andrew Yang
-/
/-!
# Formally smooth local algebras
-/

public section

open TensorProduct IsLocalRing KaehlerDifferential

variable {R S : Type*} [CommRing R] [CommRing S] [IsLocalRing S] [Algebra R S]

namespace Algebra

/--
The **Jacobian criterion** for smoothness of local algebras.
Suppose `S` is a local `R`-algebra, and `0 → I → P → S → 0` is a presentation such that
`P` is formally-smooth over `R`, `Ω[P⁄R]` is finite free over `P`,
(typically satisfied when `P` is the localization of a polynomial ring of finite type)
and `I` is finitely generated.
Then `S` is formally smooth iff `k ⊗ₛ I/I² → k ⊗ₚ Ω[P/R]` is injective,
where `k` is the residue field of `S`.
-/

Target:
theorem FormallySmooth.iff_injective_lTensor_residueField.{u}
    (P : Algebra.Extension.{u} R S)
    [FormallySmooth R P.Ring]
    [Module.Free P.Ring Ω[P.Ring⁄R]] [Module.Finite P.Ring Ω[P.Ring⁄R]]
    (h' : P.ker.FG) :
    Algebra.FormallySmooth R S ↔
      Function.Injective (P.cotangentComplex.lTensor (ResidueField S)) :=

Failed candidate:
by
  have __repair_4051b4a8ee : False := True.intro
  have : Module.Finite P.Ring P.Cotangent :=
    have : Module.Finite P.Ring P.ker := .of_fg h'
    .of_surjective _ Extension.Cotangent.mk_surjective
  have : Module.Finite S P.Cotangent := Module.Finite.of_restrictScalars_finite P.Ring _ _
  rw [← IsLocalRing.split_injective_iff_lTensor_residueField_injective,
    P.formallySmooth_iff_split_injection]

Structured Lean error:
{"kind": "type_mismatch_wrong_shape", "message": "<LEAN_FILE>:43:38: error: Type mismatch\n  True.intro\nhas type\n  True\nbut is expected to have type\n  False", "returncode": 1}

Corrected proof:

[Assistant]
by
  have : Module.Finite P.Ring P.Cotangent :=
    have : Module.Finite P.Ring P.ker := .of_fg h'
    .of_surjective _ Extension.Cotangent.mk_surjective
  have : Module.Finite S P.Cotangent := Module.Finite.of_restrictScalars_finite P.Ring _ _
  rw [← IsLocalRing.split_injective_iff_lTensor_residueField_injective,
    P.formallySmooth_iff_split_injection]

Prompt:
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.RingTheory.Flat.FaithfullyFlat.Basic
public import Mathlib.RingTheory.LocalRing.Module
public import Mathlib.RingTheory.Smooth.Basic
public import Mathlib.RingTheory.TensorProduct.Free

Namespace:
Algebra

Local safe context:
/-
Copyright (c) 2024 Andrew Yang. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Andrew Yang
-/
/-!
# Formally smooth local algebras
-/

public section

open TensorProduct IsLocalRing KaehlerDifferential

variable {R S : Type*} [CommRing R] [CommRing S] [IsLocalRing S] [Algebra R S]

namespace Algebra

/--
The **Jacobian criterion** for smoothness of local algebras.
Suppose `S` is a local `R`-algebra, and `0 → I → P → S → 0` is a presentation such that
`P` is formally-smooth over `R`, `Ω[P⁄R]` is finite free over `P`,
(typically satisfied when `P` is the localization of a polynomial ring of finite type)
and `I` is finitely generated.
Then `S` is formally smooth iff `k ⊗ₛ I/I² → k ⊗ₚ Ω[P/R]` is injective,
where `k` is the residue field of `S`.
-/

Target:
theorem FormallySmooth.iff_injective_lTensor_residueField.{u}
    (P : Algebra.Extension.{u} R S)
    [FormallySmooth R P.Ring]
    [Module.Free P.Ring Ω[P.Ring⁄R]] [Module.Finite P.Ring Ω[P.Ring⁄R]]
    (h' : P.ker.FG) :
    Algebra.FormallySmooth R S ↔
      Function.Injective (P.cotangentComplex.lTensor (ResidueField S)) :=

Failed candidate:
by
  have __repair_4051b4a8ee : False := True.intro
  have : Module.Finite P.Ring P.Cotangent :=
    have : Module.Finite P.Ring P.ker := .of_fg h'
    .of_surjective _ Extension.Cotangent.mk_surjective
  have : Module.Finite S P.Cotangent := Module.Finite.of_restrictScalars_finite P.Ring _ _
  rw [← IsLocalRing.split_injective_iff_lTensor_residueField_injective,
    P.formallySmooth_iff_split_injection]

Structured Lean error:
{"kind": "type_mismatch_wrong_shape", "message": "<LEAN_FILE>:43:38: error: Type mismatch\n  True.intro\nhas type\n  True\nbut is expected to have type\n  False", "returncode": 1}

Corrected proof:


Response:
by
  let := Localization.AtPrime.algebraOfLiesOver (q.under R) q
  rw [inertiaDeg'_def]
  apply Module.finrank_pos

[User]
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.NumberTheory.RamificationInertia.Inertia
public import Mathlib.RingTheory.QuasiFinite.Basic

Namespace:
Ideal

Local context:
/-
Copyright (c) 2026 Thomas Browning. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Thomas Browning
-/
/-!
# Inertia degree

Given a prime ideal `q` of an `R`-algebra `S`, the inertia degree of `q` over `R` is defined
to be the degree of the residue field of `q` over the residue field of its preimage `p` in `R`.

## Main definitions

* `Ideal.inertiaDeg' q R`: The inertia degree of `q` over `R`.

## Main statements

* `inertiaDeg_eq_inertiaDeg'`: The inertia degree agrees with the usual definition in the case of
  maximal ideals.
* `inertiaDeg'_tower`: Inertia degree is multiplicative in towers.
-/

@[expose] public section

namespace Ideal

section

variable {S : Type*} [CommRing S] (q : Ideal S) (R : Type*) [CommRing R] [Algebra R S]

open Classical in
/-- Given a prime ideal `q` of an `R`-algebra `S`, the inertia degree of `q` over `R` is defined
to be the degree of the residue field of `q` over the residue field of its preimage `p` in `R`.

When `q` is not prime, we use a junk value of `0`.

This will eventually replace the existing definition of `Ideal.inertiaDeg`. -/
noncomputable def inertiaDeg' : ℕ :=
  if _ : q.IsPrime then
    letI := Localization.AtPrime.algebraOfLiesOver (q.under R) q
    Module.finrank (q.under R).ResidueField q.ResidueField else 0

theorem inertiaDeg'_def [hq : q.IsPrime]
    [Algebra (Localization.AtPrime (q.under R)) (Localization.AtPrime q)]
    [Localization.AtPrime.IsLiesOverAlgebra (q.under R) q] :
    q.inertiaDeg' R = Module.finrank (q.under R).ResidueField q.ResidueField := by
  convert! dif_pos hq
  simp [Algebra.algebra_ext_iff, Localization.AtPrime.IsLiesOverAlgebra.algebraMap_eq]

theorem inertiaDeg'_of_not_isPrime (hq : ¬ q.IsPrime) : q.inertiaDeg' R = 0 :=
  dif_neg hq

Target:
theorem inertiaDeg'_pos [hq : q.IsPrime] [Module.Finite R S] : 0 < q.inertiaDeg' R :=

Proof body:

[Assistant]
by
  let := Localization.AtPrime.algebraOfLiesOver (q.under R) q
  rw [inertiaDeg'_def]
  apply Module.finrank_pos

Prompt:
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.NumberTheory.RamificationInertia.Inertia
public import Mathlib.RingTheory.QuasiFinite.Basic

Namespace:
Ideal

Local context:
/-
Copyright (c) 2026 Thomas Browning. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Thomas Browning
-/
/-!
# Inertia degree

Given a prime ideal `q` of an `R`-algebra `S`, the inertia degree of `q` over `R` is defined
to be the degree of the residue field of `q` over the residue field of its preimage `p` in `R`.

## Main definitions

* `Ideal.inertiaDeg' q R`: The inertia degree of `q` over `R`.

## Main statements

* `inertiaDeg_eq_inertiaDeg'`: The inertia degree agrees with the usual definition in the case of
  maximal ideals.
* `inertiaDeg'_tower`: Inertia degree is multiplicative in towers.
-/

@[expose] public section

namespace Ideal

section

variable {S : Type*} [CommRing S] (q : Ideal S) (R : Type*) [CommRing R] [Algebra R S]

open Classical in
/-- Given a prime ideal `q` of an `R`-algebra `S`, the inertia degree of `q` over `R` is defined
to be the degree of the residue field of `q` over the residue field of its preimage `p` in `R`.

When `q` is not prime, we use a junk value of `0`.

This will eventually replace the existing definition of `Ideal.inertiaDeg`. -/
noncomputable def inertiaDeg' : ℕ :=
  if _ : q.IsPrime then
    letI := Localization.AtPrime.algebraOfLiesOver (q.under R) q
    Module.finrank (q.under R).ResidueField q.ResidueField else 0

theorem inertiaDeg'_def [hq : q.IsPrime]
    [Algebra (Localization.AtPrime (q.under R)) (Localization.AtPrime q)]
    [Localization.AtPrime.IsLiesOverAlgebra (q.under R) q] :
    q.inertiaDeg' R = Module.finrank (q.under R).ResidueField q.ResidueField := by
  convert! dif_pos hq
  simp [Algebra.algebra_ext_iff, Localization.AtPrime.IsLiesOverAlgebra.algebraMap_eq]

theorem inertiaDeg'_of_not_isPrime (hq : ¬ q.IsPrime) : q.inertiaDeg' R = 0 :=
  dif_neg hq

Target:
theorem inertiaDeg'_pos [hq : q.IsPrime] [Module.Finite R S] : 0 < q.inertiaDeg' R :=

Proof body:


<LEAN_FILE>:150:41: error(lean.invalidField): Invalid field `nonexistentProjection`: The environment does not contain `True.nonexistentProjection`, so it is not possible to project the field `nonexistentProjection` from an expression
  True.intro
of type `True`
<LEAN_FILE>:149:0: error: unsolved goals
α : Type u_1
β : Type u_2
G H : Graph α β
hHG : H ≤ G
⊢ EqOn H.IsLoopAt G.IsLoopAt E(H)

Response:
by
  rintro e he
  ext x
  exact hHG.isLoopAt_congr he

[User]
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Combinatorics.Graph.Basic
public import Mathlib.Tactic.TFAE

Namespace:
Graph

Local safe context:
/-
Copyright (c) 2025 Peter Nelson. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Peter Nelson, Jun Kwon
-/
/-!
# Subgraphs of multigraphs

This file develops the basic theory of subgraphs for multigraphs `Graph α β`:
the subgraph relation, standard classes of subgraphs (spanning, induced, closed),
and the bottom element `⊥`.

## Main definitions

- `H ≤ G`: the subgraph relation as a partial order on graphs. This is the preferred spelling over
  `H.IsSubgraph G` which it is definitionally equal to.
- `H ≤s G` (`Graph.IsSpanningSubgraph`): `H` has the same vertex set as `G`.
- `H ≤i G` (`Graph.IsInducedSubgraph`): `H` contains every ambient link between its vertices.
- `H ≤c G` (`Graph.IsClosedSubgraph`): `H` is a union of components of `G`.
- `⊥`: empty graph with no vertices or edges as its bottom element.

## Implementation notes

Following the overall design of `Graph`, subgraphs are terms of the same type `Graph α β`
rather than a separate `Subgraph` structure. This allows us to reuse notation and lemmas
uniformly and to express the subgraph order directly as a partial order on `Graph α β`.

`G ≤ H` is the canonical spelling for "G is a subgraph of H". This is definitionally equal to
`G.IsSubgraph H` which exists only for implementation reasons.
The explicit `IsSubgraph` structure is defined so that stronger subgraph notions
(such as `IsSpanningSubgraph`, `IsInducedSubgraph`, and `IsClosedSubgraph`) can extend it.
This allows them to inherit fundamental fields and lemmas like `vertexSet_mono` and `edgeSet_mono`
without lemma duplication. However, in statements and proofs, users use `G ≤ H` instead.
The relation `≤` is the `simp` normal form, and the API is developed entirely in terms of it.

## Tags

graphs, subgraph, induced subgraph, spanning subgraph, closed subgraph
-/

public section

variable {α β : Type*} {x y z u v w : α} {e f : β} {G G₁ G₂ H H₁ H₂ K : Graph α β} {F F₁ F₂ : Set β}
   {X Y : Set α}

open Set

open scoped Sym2

namespace Graph

section Subgraph

/-- `IsSubgraph H G` is NOT the preferred spelling for the subgraph relation. Please use
`H ≤ G` instead. -/
@[mk_iff]
structure IsSubgraph (H G : Graph α β) : Prop where
  vertexSet_mono : V(H) ⊆ V(G) := by aesop
  isLink_mono : ∀ ⦃e x y⦄, H.IsLink e x y → G.IsLink e x y := by aesop

attribute [gcongr, grind →] IsSubgraph.vertexSet_mono

lemma IsSubgraph.trans (h₁ : H.IsSubgraph G) (h₂ : G.IsSubgraph G₁) : H.IsSubgraph G₁ :=
  ⟨h₁.1.trans h₂.1, fun _ _ _ h ↦ h₂.2 (h₁.2 h)⟩

lemma IsSubgraph.antisymm (h₁ : H.IsSubgraph G) (h₂ : G.IsSubgraph H) : H = G :=
  Graph.ext (h₁.1.antisymm h₂.1) fun _ _ _ ↦ ⟨(h₁.2 ·), (h₂.2 ·)⟩

/-- `H ≤ G` means `H` is a subgraph of `G`. It is defined as `V(H) ⊆ V(G)` and every link of `H`
being a link of `G`. -/
instance : PartialOrder (Graph α β) where
  le := IsSubgraph
  le_refl _ := ⟨le_rfl, fun _ _ _ h ↦ h⟩
  le_trans _ _ _ h₁ h₂ := h₁.trans h₂
  le_antisymm G H h₁ h₂ := h₁.antisymm h₂

@[simp]
lemma isSubgraph_iff_le : H.IsSubgraph G ↔ H ≤ G := .rfl

@[gcongr]
lemma IsLink.mono (hHG : H ≤ G) (h : H.IsLink e x y) : G.IsLink e x y := hHG.2 h

@[gcongr, grind →]
lemma IsSubgraph.edgeSet_mono (h : H ≤ G) : E(H) ⊆ E(G) := by
  intro e he
  obtain ⟨x, y, h'⟩ := exists_isLink_of_mem_edgeSet he
  exact (h'.mono h).edge_mem

private lemma IsLink.anti_of_mem (h : G.IsLink e x y) (hHG : H ≤ G) (he : e ∈ E(H)) :
    H.IsLink e x y := by
  obtain ⟨u, v, huv⟩ := exists_isLink_of_mem_edgeSet he
  obtain ⟨rfl, rfl⟩ | ⟨rfl, rfl⟩ := (huv.mono hHG).eq_and_eq_or_eq_and_eq h
  · assumption
  exact huv.symm

lemma IsSubgraph.isLink_iff (hHG : H ≤ G) (he : e ∈ E(H)) : H.IsLink e x y ↔ G.IsLink e x y :=
  ⟨fun h ↦ h.mono hHG, fun h ↦ h.anti_of_mem hHG he⟩

lemma IsSubgraph.isLink_eqOn (hHG : H ≤ G) : EqOn H.IsLink G.IsLink E(H) := by
  rintro e he
  ext x y
  exact isLink_iff hHG he

/-- Two subgraphs of the same graph are compatible. -/
lemma Compatible.of_le_le (hH₁G : H₁ ≤ G) (hH₂G : H₂ ≤ G) : H₁.Compatible H₂ :=
  fun _ he₁ he₂ _ _ ↦ hH₁G.isLink_iff he₁ |>.trans <| (hH₂G.isLink_iff he₂).symm

lemma Compatible.of_le (hHG : H ≤ G) : H.Compatible G := .of_le_le hHG le_rfl
lemma Compatible.of_ge (hHG : G ≤ H) : H.Compatible G := .of_le_le le_rfl hHG

alias IsSubgraph.compatible := Compatible.of_le
alias IsSubgraph.compatible' := Compatible.of_ge

lemma Compatible.anti_left (hG₁G : G₁ ≤ G) (h : Compatible G H) : Compatible G₁ H :=
  fun _ he₁ he₂ _ _ ↦ hG₁G.isLink_iff he₁ |>.trans <| h (hG₁G.edgeSet_mono he₁) he₂ ..

lemma Compatible.anti_right (hH₁H : H₁ ≤ H) (h : Compatible G H) : Compatible G H₁ :=
  (h.symm.anti_left hH₁H).symm

lemma Compatible.anti (hG₁G : G₁ ≤ G) (hH₁H : H₁ ≤ H) (h : G.Compatible H) : G₁.Compatible H₁ :=
  (h.anti_left hG₁G).anti_right hH₁H

@[gcongr]
lemma Inc.mono (hHG : H ≤ G) (h : H.Inc e x) : G.Inc e x :=
  (h.choose_spec.mono hHG).inc_left

lemma IsSubgraph.inc_congr (hHG : H ≤ G) (he : e ∈ E(H)) : H.Inc e x ↔ G.Inc e x := by
  simp_rw [Graph.Inc, hHG.isLink_iff he]

lemma IsSubgraph.inc_eqOn (hHG : H ≤ G) : EqOn H.Inc G.Inc E(H) := by
  rintro e he
  ext x
  exact hHG.inc_congr he

lemma IsLoopAt.mono (hHG : H ≤ G) (h : H.IsLoopAt e x) : G.IsLoopAt e x :=
  IsLink.mono hHG h

lemma IsSubgraph.isLoopAt_congr (hHG : H ≤ G) (he : e ∈ E(H)) :
    H.IsLoopAt e x ↔ G.IsLoopAt e x := by
  unfold Graph.IsLoopAt
  rw [hHG.isLink_iff he]

Target:
lemma IsSubgraph.isLoopAt_eqOn (hHG : H ≤ G) : EqOn H.IsLoopAt G.IsLoopAt E(H) :=

Failed candidate:
by
  have __repair_7a1c44fb91 := True.intro.nonexistentProjection
  rintro e he
  ext x
  exact hHG.isLoopAt_congr he

Structured Lean error:
{"kind": "invalid_projection", "message": "<LEAN_FILE>:150:41: error(lean.invalidField): Invalid field `nonexistentProjection`: The environment does not contain `True.nonexistentProjection`, so it is not possible to project the field `nonexistentProjection` from an expression\n  True.intro\nof type `True`\n<LEAN_FILE>:149:0: error: unsolved goals\nα : Type u_1\nβ : Type u_2\nG H : Graph α β\nhHG : H ≤ G\n⊢ EqOn H.IsLoopAt G.IsLoopAt E(H)", "returncode": 1}

Corrected proof:

[Assistant]
by
  rintro e he
  ext x
  exact hHG.isLoopAt_congr he

Prompt:
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Combinatorics.Graph.Basic
public import Mathlib.Tactic.TFAE

Namespace:
Graph

Local safe context:
/-
Copyright (c) 2025 Peter Nelson. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Peter Nelson, Jun Kwon
-/
/-!
# Subgraphs of multigraphs

This file develops the basic theory of subgraphs for multigraphs `Graph α β`:
the subgraph relation, standard classes of subgraphs (spanning, induced, closed),
and the bottom element `⊥`.

## Main definitions

- `H ≤ G`: the subgraph relation as a partial order on graphs. This is the preferred spelling over
  `H.IsSubgraph G` which it is definitionally equal to.
- `H ≤s G` (`Graph.IsSpanningSubgraph`): `H` has the same vertex set as `G`.
- `H ≤i G` (`Graph.IsInducedSubgraph`): `H` contains every ambient link between its vertices.
- `H ≤c G` (`Graph.IsClosedSubgraph`): `H` is a union of components of `G`.
- `⊥`: empty graph with no vertices or edges as its bottom element.

## Implementation notes

Following the overall design of `Graph`, subgraphs are terms of the same type `Graph α β`
rather than a separate `Subgraph` structure. This allows us to reuse notation and lemmas
uniformly and to express the subgraph order directly as a partial order on `Graph α β`.

`G ≤ H` is the canonical spelling for "G is a subgraph of H". This is definitionally equal to
`G.IsSubgraph H` which exists only for implementation reasons.
The explicit `IsSubgraph` structure is defined so that stronger subgraph notions
(such as `IsSpanningSubgraph`, `IsInducedSubgraph`, and `IsClosedSubgraph`) can extend it.
This allows them to inherit fundamental fields and lemmas like `vertexSet_mono` and `edgeSet_mono`
without lemma duplication. However, in statements and proofs, users use `G ≤ H` instead.
The relation `≤` is the `simp` normal form, and the API is developed entirely in terms of it.

## Tags

graphs, subgraph, induced subgraph, spanning subgraph, closed subgraph
-/

public section

variable {α β : Type*} {x y z u v w : α} {e f : β} {G G₁ G₂ H H₁ H₂ K : Graph α β} {F F₁ F₂ : Set β}
   {X Y : Set α}

open Set

open scoped Sym2

namespace Graph

section Subgraph

/-- `IsSubgraph H G` is NOT the preferred spelling for the subgraph relation. Please use
`H ≤ G` instead. -/
@[mk_iff]
structure IsSubgraph (H G : Graph α β) : Prop where
  vertexSet_mono : V(H) ⊆ V(G) := by aesop
  isLink_mono : ∀ ⦃e x y⦄, H.IsLink e x y → G.IsLink e x y := by aesop

attribute [gcongr, grind →] IsSubgraph.vertexSet_mono

lemma IsSubgraph.trans (h₁ : H.IsSubgraph G) (h₂ : G.IsSubgraph G₁) : H.IsSubgraph G₁ :=
  ⟨h₁.1.trans h₂.1, fun _ _ _ h ↦ h₂.2 (h₁.2 h)⟩

lemma IsSubgraph.antisymm (h₁ : H.IsSubgraph G) (h₂ : G.IsSubgraph H) : H = G :=
  Graph.ext (h₁.1.antisymm h₂.1) fun _ _ _ ↦ ⟨(h₁.2 ·), (h₂.2 ·)⟩

/-- `H ≤ G` means `H` is a subgraph of `G`. It is defined as `V(H) ⊆ V(G)` and every link of `H`
being a link of `G`. -/
instance : PartialOrder (Graph α β) where
  le := IsSubgraph
  le_refl _ := ⟨le_rfl, fun _ _ _ h ↦ h⟩
  le_trans _ _ _ h₁ h₂ := h₁.trans h₂
  le_antisymm G H h₁ h₂ := h₁.antisymm h₂

@[simp]
lemma isSubgraph_iff_le : H.IsSubgraph G ↔ H ≤ G := .rfl

@[gcongr]
lemma IsLink.mono (hHG : H ≤ G) (h : H.IsLink e x y) : G.IsLink e x y := hHG.2 h

@[gcongr, grind →]
lemma IsSubgraph.edgeSet_mono (h : H ≤ G) : E(H) ⊆ E(G) := by
  intro e he
  obtain ⟨x, y, h'⟩ := exists_isLink_of_mem_edgeSet he
  exact (h'.mono h).edge_mem

private lemma IsLink.anti_of_mem (h : G.IsLink e x y) (hHG : H ≤ G) (he : e ∈ E(H)) :
    H.IsLink e x y := by
  obtain ⟨u, v, huv⟩ := exists_isLink_of_mem_edgeSet he
  obtain ⟨rfl, rfl⟩ | ⟨rfl, rfl⟩ := (huv.mono hHG).eq_and_eq_or_eq_and_eq h
  · assumption
  exact huv.symm

lemma IsSubgraph.isLink_iff (hHG : H ≤ G) (he : e ∈ E(H)) : H.IsLink e x y ↔ G.IsLink e x y :=
  ⟨fun h ↦ h.mono hHG, fun h ↦ h.anti_of_mem hHG he⟩

lemma IsSubgraph.isLink_eqOn (hHG : H ≤ G) : EqOn H.IsLink G.IsLink E(H) := by
  rintro e he
  ext x y
  exact isLink_iff hHG he

/-- Two subgraphs of the same graph are compatible. -/
lemma Compatible.of_le_le (hH₁G : H₁ ≤ G) (hH₂G : H₂ ≤ G) : H₁.Compatible H₂ :=
  fun _ he₁ he₂ _ _ ↦ hH₁G.isLink_iff he₁ |>.trans <| (hH₂G.isLink_iff he₂).symm

lemma Compatible.of_le (hHG : H ≤ G) : H.Compatible G := .of_le_le hHG le_rfl
lemma Compatible.of_ge (hHG : G ≤ H) : H.Compatible G := .of_le_le le_rfl hHG

alias IsSubgraph.compatible := Compatible.of_le
alias IsSubgraph.compatible' := Compatible.of_ge

lemma Compatible.anti_left (hG₁G : G₁ ≤ G) (h : Compatible G H) : Compatible G₁ H :=
  fun _ he₁ he₂ _ _ ↦ hG₁G.isLink_iff he₁ |>.trans <| h (hG₁G.edgeSet_mono he₁) he₂ ..

lemma Compatible.anti_right (hH₁H : H₁ ≤ H) (h : Compatible G H) : Compatible G H₁ :=
  (h.symm.anti_left hH₁H).symm

lemma Compatible.anti (hG₁G : G₁ ≤ G) (hH₁H : H₁ ≤ H) (h : G.Compatible H) : G₁.Compatible H₁ :=
  (h.anti_left hG₁G).anti_right hH₁H

@[gcongr]
lemma Inc.mono (hHG : H ≤ G) (h : H.Inc e x) : G.Inc e x :=
  (h.choose_spec.mono hHG).inc_left

lemma IsSubgraph.inc_congr (hHG : H ≤ G) (he : e ∈ E(H)) : H.Inc e x ↔ G.Inc e x := by
  simp_rw [Graph.Inc, hHG.isLink_iff he]

lemma IsSubgraph.inc_eqOn (hHG : H ≤ G) : EqOn H.Inc G.Inc E(H) := by
  rintro e he
  ext x
  exact hHG.inc_congr he

lemma IsLoopAt.mono (hHG : H ≤ G) (h : H.IsLoopAt e x) : G.IsLoopAt e x :=
  IsLink.mono hHG h

lemma IsSubgraph.isLoopAt_congr (hHG : H ≤ G) (he : e ∈ E(H)) :
    H.IsLoopAt e x ↔ G.IsLoopAt e x := by
  unfold Graph.IsLoopAt
  rw [hHG.isLink_iff he]

Target:
lemma IsSubgraph.isLoopAt_eqOn (hHG : H ≤ G) : EqOn H.IsLoopAt G.IsLoopAt E(H) :=

Failed candidate:
by
  have __repair_7a1c44fb91 := True.intro.nonexistentProjection
  rintro e he
  ext x
  exact hHG.isLoopAt_congr he

Structured Lean error:
{"kind": "invalid_projection", "message": "<LEAN_FILE>:150:41: error(lean.invalidField): Invalid field `nonexistentProjection`: The environment does not contain `True.nonexistentProjection`, so it is not possible to project the field `nonexistentProjection` from an expression\n  True.intro\nof type `True`\n<LEAN_FILE>:149:0: error: unsolved goals\nα : Type u_1\nβ : Type u_2\nG H : Graph α β\nhHG : H ≤ G\n⊢ EqOn H.IsLoopAt G.IsLoopAt E(H)", "returncode": 1}

Corrected proof:


<LEAN_FILE>:112:42: error(lean.synthInstanceFailed): failed to synthesize instance of type class
  Fact False

Hint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.

Response:
by
  rw [ZMod.minOrder hp.ne_zero hp.ne_one, hp.minFac_eq]

[User]
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Algebra.Group.Torsion
public import Mathlib.Data.ENat.Lattice
public import Mathlib.Data.ZMod.QuotientGroup

Namespace:
ZMod

Local safe context:
/-
Copyright (c) 2023 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
/-!
# Minimum order of an element

This file defines the minimum order of an element of a monoid.

## Main declarations

* `Monoid.minOrder`: The minimum order of an element of a given monoid.
* `Monoid.minOrder_eq_top`: The minimum order is infinite iff the monoid is torsion-free.
* `ZMod.minOrder`: The minimum order of $ℤ/nℤ$ is the smallest factor of `n`, unless `n = 0, 1`.
-/

@[expose] public section

open Subgroup

variable {G α : Type*}

namespace Monoid
section Monoid
variable (α) [Monoid α]

/-- The minimum order of a non-identity element. Also the minimum size of a nontrivial subgroup, see
`Monoid.le_minOrder_iff_forall_subgroup`. Returns `∞` if the monoid is torsion-free. -/
@[to_additive /-- The minimum order of a non-identity element. Also the minimum size of a nontrivial
subgroup, see `AddMonoid.le_minOrder_iff_forall_addSubgroup`. Returns `∞` if the monoid is
torsion-free. -/]
noncomputable def minOrder : ℕ∞ := ⨅ (a : α) (_ha : a ≠ 1) (_ha' : IsOfFinOrder a), orderOf a

variable {α} {a : α}

@[to_additive (attr := simp)]
lemma le_minOrder {n : ℕ∞} :
    n ≤ minOrder α ↔ ∀ ⦃a : α⦄, a ≠ 1 → IsOfFinOrder a → n ≤ orderOf a := by simp [minOrder]

@[to_additive]
lemma minOrder_le_orderOf (ha : a ≠ 1) (ha' : IsOfFinOrder a) : minOrder α ≤ orderOf a :=
  le_minOrder.1 le_rfl ha ha'

end Monoid

section Group
variable [Group G] {s : Subgroup G}

@[to_additive]
lemma le_minOrder_iff_forall_subgroup {n : ℕ∞} :
    n ≤ minOrder G ↔ ∀ ⦃s : Subgroup G⦄, s ≠ ⊥ → (s : Set G).Finite → n ≤ Nat.card s := by
  rw [le_minOrder]
  refine ⟨fun h s hs hs' ↦ ?_, fun h a ha ha' ↦ ?_⟩
  · obtain ⟨a, has, ha⟩ := s.bot_or_exists_ne_one.resolve_left hs
    exact
      (h ha <| finite_zpowers.1 <| hs'.subset <| zpowers_le.2 has).trans
        (WithTop.coe_le_coe.2 <| s.orderOf_le_card hs' has)
  · simpa using h (zpowers_ne_bot.2 ha) ha'.finite_zpowers

@[to_additive]
lemma minOrder_le_natCard (hs : s ≠ ⊥) (hs' : (s : Set G).Finite) : minOrder G ≤ Nat.card s :=
  le_minOrder_iff_forall_subgroup.1 le_rfl hs hs'

@[to_additive (attr := simp)]
lemma minOrder_eq_top [IsMulTorsionFree G] : minOrder G = ⊤ := by
  simpa [minOrder] using fun _ ↦ not_isOfFinOrder_of_isMulTorsionFree

end Group

section CommGroup
variable [CommGroup G] {s : Subgroup G}

@[to_additive (attr := simp)]
lemma minOrder_eq_top_iff : minOrder G = ⊤ ↔ IsMulTorsionFree G := by
  simp [minOrder, isMulTorsionFree_iff_not_isOfFinOrder]

end CommGroup
end Monoid

open AddMonoid AddSubgroup Nat Set

namespace ZMod

@[simp]
protected lemma minOrder {n : ℕ} (hn : n ≠ 0) (hn₁ : n ≠ 1) : minOrder (ZMod n) = n.minFac := by
  have : Fact (1 < n) := ⟨one_lt_iff_ne_zero_and_ne_one.mpr ⟨hn, hn₁⟩⟩
  classical
  have : (↑(n / n.minFac) : ZMod n) ≠ 0 := by
    rw [Ne, ringChar.spec, ringChar.eq (ZMod n) n]
    exact
      not_dvd_of_pos_of_lt (Nat.div_pos (minFac_le hn.bot_lt) n.minFac_pos)
        (div_lt_self hn.bot_lt (minFac_prime hn₁).one_lt)
  refine ((minOrder_le_natCard (zmultiples_eq_bot.not.2 this) <| toFinite _).trans ?_).antisymm <|
    le_minOrder_iff_forall_addSubgroup.2 fun s hs _ ↦ ?_
  · rw [Nat.card_zmultiples, ZMod.addOrderOf_coe _ hn,
      gcd_eq_right (div_dvd_of_dvd n.minFac_dvd), Nat.div_div_self n.minFac_dvd hn]
  · haveI : Nontrivial s := s.bot_or_nontrivial.resolve_left hs
    exact WithTop.coe_le_coe.2 <| minFac_le_of_dvd Finite.one_lt_card <|
      (card_addSubgroup_dvd_card _).trans n.card_zmod.dvd

@[simp]

Target:
lemma minOrder_of_prime {p : ℕ} (hp : p.Prime) : minOrder (ZMod p) = p :=

Failed candidate:
by
  let __repair_24ca182098 : Fact False := inferInstance
  rw [ZMod.minOrder hp.ne_zero hp.ne_one, hp.minFac_eq]

Structured Lean error:
{"kind": "typeclass_synthesis", "message": "<LEAN_FILE>:112:42: error(lean.synthInstanceFailed): failed to synthesize instance of type class\n  Fact False\n\nHint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.", "returncode": 1}

Corrected proof:

[Assistant]
by
  rw [ZMod.minOrder hp.ne_zero hp.ne_one, hp.minFac_eq]

Prompt:
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.Algebra.Group.Torsion
public import Mathlib.Data.ENat.Lattice
public import Mathlib.Data.ZMod.QuotientGroup

Namespace:
ZMod

Local safe context:
/-
Copyright (c) 2023 Yaël Dillies. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Yaël Dillies
-/
/-!
# Minimum order of an element

This file defines the minimum order of an element of a monoid.

## Main declarations

* `Monoid.minOrder`: The minimum order of an element of a given monoid.
* `Monoid.minOrder_eq_top`: The minimum order is infinite iff the monoid is torsion-free.
* `ZMod.minOrder`: The minimum order of $ℤ/nℤ$ is the smallest factor of `n`, unless `n = 0, 1`.
-/

@[expose] public section

open Subgroup

variable {G α : Type*}

namespace Monoid
section Monoid
variable (α) [Monoid α]

/-- The minimum order of a non-identity element. Also the minimum size of a nontrivial subgroup, see
`Monoid.le_minOrder_iff_forall_subgroup`. Returns `∞` if the monoid is torsion-free. -/
@[to_additive /-- The minimum order of a non-identity element. Also the minimum size of a nontrivial
subgroup, see `AddMonoid.le_minOrder_iff_forall_addSubgroup`. Returns `∞` if the monoid is
torsion-free. -/]
noncomputable def minOrder : ℕ∞ := ⨅ (a : α) (_ha : a ≠ 1) (_ha' : IsOfFinOrder a), orderOf a

variable {α} {a : α}

@[to_additive (attr := simp)]
lemma le_minOrder {n : ℕ∞} :
    n ≤ minOrder α ↔ ∀ ⦃a : α⦄, a ≠ 1 → IsOfFinOrder a → n ≤ orderOf a := by simp [minOrder]

@[to_additive]
lemma minOrder_le_orderOf (ha : a ≠ 1) (ha' : IsOfFinOrder a) : minOrder α ≤ orderOf a :=
  le_minOrder.1 le_rfl ha ha'

end Monoid

section Group
variable [Group G] {s : Subgroup G}

@[to_additive]
lemma le_minOrder_iff_forall_subgroup {n : ℕ∞} :
    n ≤ minOrder G ↔ ∀ ⦃s : Subgroup G⦄, s ≠ ⊥ → (s : Set G).Finite → n ≤ Nat.card s := by
  rw [le_minOrder]
  refine ⟨fun h s hs hs' ↦ ?_, fun h a ha ha' ↦ ?_⟩
  · obtain ⟨a, has, ha⟩ := s.bot_or_exists_ne_one.resolve_left hs
    exact
      (h ha <| finite_zpowers.1 <| hs'.subset <| zpowers_le.2 has).trans
        (WithTop.coe_le_coe.2 <| s.orderOf_le_card hs' has)
  · simpa using h (zpowers_ne_bot.2 ha) ha'.finite_zpowers

@[to_additive]
lemma minOrder_le_natCard (hs : s ≠ ⊥) (hs' : (s : Set G).Finite) : minOrder G ≤ Nat.card s :=
  le_minOrder_iff_forall_subgroup.1 le_rfl hs hs'

@[to_additive (attr := simp)]
lemma minOrder_eq_top [IsMulTorsionFree G] : minOrder G = ⊤ := by
  simpa [minOrder] using fun _ ↦ not_isOfFinOrder_of_isMulTorsionFree

end Group

section CommGroup
variable [CommGroup G] {s : Subgroup G}

@[to_additive (attr := simp)]
lemma minOrder_eq_top_iff : minOrder G = ⊤ ↔ IsMulTorsionFree G := by
  simp [minOrder, isMulTorsionFree_iff_not_isOfFinOrder]

end CommGroup
end Monoid

open AddMonoid AddSubgroup Nat Set

namespace ZMod

@[simp]
protected lemma minOrder {n : ℕ} (hn : n ≠ 0) (hn₁ : n ≠ 1) : minOrder (ZMod n) = n.minFac := by
  have : Fact (1 < n) := ⟨one_lt_iff_ne_zero_and_ne_one.mpr ⟨hn, hn₁⟩⟩
  classical
  have : (↑(n / n.minFac) : ZMod n) ≠ 0 := by
    rw [Ne, ringChar.spec, ringChar.eq (ZMod n) n]
    exact
      not_dvd_of_pos_of_lt (Nat.div_pos (minFac_le hn.bot_lt) n.minFac_pos)
        (div_lt_self hn.bot_lt (minFac_prime hn₁).one_lt)
  refine ((minOrder_le_natCard (zmultiples_eq_bot.not.2 this) <| toFinite _).trans ?_).antisymm <|
    le_minOrder_iff_forall_addSubgroup.2 fun s hs _ ↦ ?_
  · rw [Nat.card_zmultiples, ZMod.addOrderOf_coe _ hn,
      gcd_eq_right (div_dvd_of_dvd n.minFac_dvd), Nat.div_div_self n.minFac_dvd hn]
  · haveI : Nontrivial s := s.bot_or_nontrivial.resolve_left hs
    exact WithTop.coe_le_coe.2 <| minFac_le_of_dvd Finite.one_lt_card <|
      (card_addSubgroup_dvd_card _).trans n.card_zmod.dvd

@[simp]

Target:
lemma minOrder_of_prime {p : ℕ} (hp : p.Prime) : minOrder (ZMod p) = p :=

Failed candidate:
by
  let __repair_24ca182098 : Fact False := inferInstance
  rw [ZMod.minOrder hp.ne_zero hp.ne_one, hp.minFac_eq]

Structured Lean error:
{"kind": "typeclass_synthesis", "message": "<LEAN_FILE>:112:42: error(lean.synthInstanceFailed): failed to synthesize instance of type class\n  Fact False\n\nHint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command.", "returncode": 1}

Corrected proof:


Response:
by
  let e := MulEquivClass.toMulEquiv e
  exact ⟨comap_prime e e.symm fun a => by simp,
    fun h => (comap_prime e.symm e fun a => by simp) <| (e.symm_apply_apply p).substr h⟩

[User]
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.Algebra.Divisibility.Hom
public import Mathlib.Algebra.Group.Irreducible.Lemmas
public import Mathlib.Algebra.GroupWithZero.Equiv
public import Mathlib.Algebra.Prime.Defs
public import Mathlib.Order.Monotone.Defs

Namespace:
(root)

Local context:
/-
Copyright (c) 2018 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Jens Wagemaker
-/
/-!
# Associated, prime, and irreducible elements.

In this file we define the predicate `Prime p`
saying that an element of a commutative monoid with zero is prime.
Namely, `Prime p` means that `p` isn't zero, it isn't a unit,
and `p ∣ a * b → p ∣ a ∨ p ∣ b` for all `a`, `b`;

In decomposition monoids (e.g., `ℕ`, `ℤ`), this predicate is equivalent to `Irreducible`,
however this is not true in general.

We also define an equivalence relation `Associated`
saying that two elements of a monoid differ by a multiplication by a unit.
Then we show that the quotient type `Associates` is a monoid
and prove basic properties of this quotient.
-/

public section

assert_not_exists IsOrderedMonoid Multiset

variable {M N : Type*}

section Prime

variable [CommMonoidWithZero M]

section Map

variable [CommMonoidWithZero N] {F : Type*} {G : Type*} [FunLike F M N]
variable [MonoidWithZeroHomClass F M N] [FunLike G N M] [MulHomClass G N M]
variable (f : F) (g : G) {p : M}

theorem comap_prime (hinv : ∀ a, g (f a : N) = a) (hp : Prime (f p)) : Prime p :=
  ⟨fun h => hp.1 <| by simp [h], fun h => hp.2.1 <| h.map f, fun a b h => by
    refine
        (hp.2.2 (f a) (f b) <| by
              convert! map_dvd f h
              simp).imp
          ?_ ?_ <;>
      · intro h
        convert! ← map_dvd g h <;> apply hinv⟩

Target:
theorem MulEquiv.prime_iff {E : Type*} [EquivLike E M N] [MulEquivClass E M N] (e : E) :
    Prime (e p) ↔ Prime p :=

Proof body:

[Assistant]
by
  let e := MulEquivClass.toMulEquiv e
  exact ⟨comap_prime e e.symm fun a => by simp,
    fun h => (comap_prime e.symm e fun a => by simp) <| (e.symm_apply_apply p).substr h⟩

Prompt:
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.Algebra.Divisibility.Hom
public import Mathlib.Algebra.Group.Irreducible.Lemmas
public import Mathlib.Algebra.GroupWithZero.Equiv
public import Mathlib.Algebra.Prime.Defs
public import Mathlib.Order.Monotone.Defs

Namespace:
(root)

Local context:
/-
Copyright (c) 2018 Johannes Hölzl. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Johannes Hölzl, Jens Wagemaker
-/
/-!
# Associated, prime, and irreducible elements.

In this file we define the predicate `Prime p`
saying that an element of a commutative monoid with zero is prime.
Namely, `Prime p` means that `p` isn't zero, it isn't a unit,
and `p ∣ a * b → p ∣ a ∨ p ∣ b` for all `a`, `b`;

In decomposition monoids (e.g., `ℕ`, `ℤ`), this predicate is equivalent to `Irreducible`,
however this is not true in general.

We also define an equivalence relation `Associated`
saying that two elements of a monoid differ by a multiplication by a unit.
Then we show that the quotient type `Associates` is a monoid
and prove basic properties of this quotient.
-/

public section

assert_not_exists IsOrderedMonoid Multiset

variable {M N : Type*}

section Prime

variable [CommMonoidWithZero M]

section Map

variable [CommMonoidWithZero N] {F : Type*} {G : Type*} [FunLike F M N]
variable [MonoidWithZeroHomClass F M N] [FunLike G N M] [MulHomClass G N M]
variable (f : F) (g : G) {p : M}

theorem comap_prime (hinv : ∀ a, g (f a : N) = a) (hp : Prime (f p)) : Prime p :=
  ⟨fun h => hp.1 <| by simp [h], fun h => hp.2.1 <| h.map f, fun a b h => by
    refine
        (hp.2.2 (f a) (f b) <| by
              convert! map_dvd f h
              simp).imp
          ?_ ?_ <;>
      · intro h
        convert! ← map_dvd g h <;> apply hinv⟩

Target:
theorem MulEquiv.prime_iff {E : Type*} [EquivLike E M N] [MulEquivClass E M N] (e : E) :
    Prime (e p) ↔ Prime p :=

Proof body:


Response:
by
  let R := MvPolynomial σ F
  let K := FractionRing R
  refine ((rank_le_card _ _).trans ?_).antisymm ?_
  · rw [FractionRing.cardinalMk, MvPolynomial.cardinalMk_eq_max_lift]
  have hinj := IsFractionRing.injective R K
  have h1 := (IsScalarTower.toAlgHom F R K).toLinearMap.rank_le_of_injective hinj
  rw [MvPolynomial.rank_eq_lift, mk_finsupp_nat, lift_max, lift_aleph0, max_le_iff] at h1
  obtain ⟨i⟩ := ‹Nonempty σ›
  have hx : Transcendental F (algebraMap R K (MvPolynomial.X i)) :=
    (transcendental_algebraMap_iff hinj).2 (MvPolynomial.transcendental_X F i)
  have h2 := hx.linearIndependent_sub_inv.cardinal_lift_le_rank
  rw [lift_id'.{v, u}, lift_umax.{v, u}] at h2
  exact max_le (max_le h2 h1.1) h1.2

[User]
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.Algebra.MvPolynomial.Cardinal
public import Mathlib.RingTheory.Algebraic.LinearIndependent
public import Mathlib.RingTheory.Algebraic.MvPolynomial
public import Mathlib.RingTheory.Localization.Cardinality
public import Mathlib.RingTheory.MvPolynomial

Namespace:
(root)

Local context:
/-
Copyright (c) 2024 Jz Pan. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jz Pan
-/
/-!
# Rank of multivariate rational function field
-/

public section

noncomputable section

universe u v

open Cardinal in

Target:
theorem MvRatFunc.rank_eq_max_lift
    {σ : Type u} {F : Type v} [Field F] [Nonempty σ] :
    Module.rank F (FractionRing (MvPolynomial σ F)) = lift.{u} #F ⊔ lift.{v} #σ ⊔ ℵ₀ :=

Proof body:

[Assistant]
by
  let R := MvPolynomial σ F
  let K := FractionRing R
  refine ((rank_le_card _ _).trans ?_).antisymm ?_
  · rw [FractionRing.cardinalMk, MvPolynomial.cardinalMk_eq_max_lift]
  have hinj := IsFractionRing.injective R K
  have h1 := (IsScalarTower.toAlgHom F R K).toLinearMap.rank_le_of_injective hinj
  rw [MvPolynomial.rank_eq_lift, mk_finsupp_nat, lift_max, lift_aleph0, max_le_iff] at h1
  obtain ⟨i⟩ := ‹Nonempty σ›
  have hx : Transcendental F (algebraMap R K (MvPolynomial.X i)) :=
    (transcendental_algebraMap_iff hinj).2 (MvPolynomial.transcendental_X F i)
  have h2 := hx.linearIndependent_sub_inv.cardinal_lift_le_rank
  rw [lift_id'.{v, u}, lift_umax.{v, u}] at h2
  exact max_le (max_le h2 h1.1) h1.2

Prompt:
Return exactly one Lean proof body beginning with `by`. Do not emit prose, fences, declarations, sorry, admit, by?, or warnings.

Imports:
public import Mathlib.Algebra.MvPolynomial.Cardinal
public import Mathlib.RingTheory.Algebraic.LinearIndependent
public import Mathlib.RingTheory.Algebraic.MvPolynomial
public import Mathlib.RingTheory.Localization.Cardinality
public import Mathlib.RingTheory.MvPolynomial

Namespace:
(root)

Local context:
/-
Copyright (c) 2024 Jz Pan. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Jz Pan
-/
/-!
# Rank of multivariate rational function field
-/

public section

noncomputable section

universe u v

open Cardinal in

Target:
theorem MvRatFunc.rank_eq_max_lift
    {σ : Type u} {F : Type v} [Field F] [Nonempty σ] :
    Module.rank F (FractionRing (MvPolynomial σ F)) = lift.{u} #F ⊔ lift.{v} #σ ⊔ ℵ₀ :=

Proof body:


<LEAN_FILE>:45:41: error(lean.invalidField): Invalid field `nonexistentProjection`: The environment does not contain `True.nonexistentProjection`, so it is not possible to project the field `nonexistentProjection` from an expression
  True.intro
of type `True`
<LEAN_FILE>:44:0: error: unsolved goals
R : Type u_1
S : Type u_2
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : Algebra R S
f : R[X] →ₐ[R] S
P : Ideal S
inst✝¹ : P.IsPrime
inst✝ : Algebra.WeaklyQuasiFiniteAt R P
⊢ Ideal.map C (Ideal.under R P) < Ideal.comap (↑f) P

Response:
by
  algebraize [f.toRingHom]
  refine lt_of_le_of_ne (Ideal.map_le_iff_le_comap.mpr ?_) fun e ↦ ?_
  · rw [Ideal.comap_comap, ← algebraMap_eq, f.comp_algebraMap]
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) (P.under R[X])
  let := Localization.AtPrime.algebraOfLiesOver (P.under R[X]) P
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) P
  have : Module.Finite (Ideal.under R P).ResidueField P.ResidueField :=
    Algebra.WeaklyQuasiFiniteAt.finite_residueField ..
  have : Module.Finite (P.under R).ResidueField (P.under R[X]).ResidueField :=
    .of_injective (IsScalarTower.toAlgHom _ _ P.ResidueField).toLinearMap
      (algebraMap (P.under R[X]).ResidueField P.ResidueField).injective
  have : Module.Finite (P.under R).ResidueField (RatFunc (P.under R).ResidueField) :=
    .of_surjective (residueFieldMapCAlgEquiv _ (P.under _) e.symm).toLinearMap
      (residueFieldMapCAlgEquiv _ (P.under _) e.symm).surjective
  exact RatFunc.transcendental_X (K := (P.under R).ResidueField)
    (Algebra.IsIntegral.isIntegral _).isAlgebraic

[User]
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.RingTheory.LocalRing.ResidueField.Polynomial
public import Mathlib.RingTheory.QuasiFinite.Weakly

Namespace:
Polynomial

Local safe context:
/-
Copyright (c) 2025 Andrew Yang. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Andrew Yang
-/
/-! # Quasi-finite primes in polynomial algebras -/

@[expose] public section

variable {R S T : Type*} [CommRing R] [CommRing S] [CommRing T]
  [Algebra R S] [Algebra R T] [Algebra S T] [IsScalarTower R S T]

namespace Polynomial

attribute [local instance] Algebra.WeaklyQuasiFiniteAt.finite_locoalization in
lemma not_weaklyQuasiFiniteAt (P : Ideal R[X]) [P.IsPrime] : ¬ Algebra.WeaklyQuasiFiniteAt R P := by
  intro H
  wlog hR : IsField R
  · let p := P.under R
    obtain ⟨Q, hQ⟩ := (PrimeSpectrum.preimageEquivFiber R R[X]
        ⟨p, inferInstance⟩).symm.surjective ⟨⟨P, ‹_›⟩, rfl⟩
    have inst : Algebra.WeaklyQuasiFiniteAt p.ResidueField Q.asIdeal :=
      .baseChange P Q.asIdeal congr($(hQ.symm).1.1)
    exact this (Q.asIdeal.comap (polyEquivTensor' R p.ResidueField).toRingHom)
      inferInstance (Field.toIsField _)
  let := hR.toField
  have := Module.Finite.of_injective
    (IsScalarTower.toAlgHom R R[X] (Localization.AtPrime P)).toLinearMap
    (IsLocalization.injective _ P.primeCompl_le_nonZeroDivisors)
  exact transcendental_X R (Algebra.IsIntegral.isIntegral X).isAlgebraic

/-- `R[X]` is not quasi-finite over `R` at any prime. -/
lemma not_quasiFiniteAt (P : Ideal R[X]) [P.IsPrime] : ¬ Algebra.QuasiFiniteAt R P :=
  fun _ ↦ not_weaklyQuasiFiniteAt P inferInstance

Target:
lemma map_under_lt_comap_of_weaklyQuasiFiniteAt
    (f : R[X] →ₐ[R] S) (P : Ideal S) [P.IsPrime] [Algebra.WeaklyQuasiFiniteAt R P] :
    (P.under R).map C < P.comap (f : R[X] →+* S) :=

Failed candidate:
by
  have __repair_d1efe1cad3 := True.intro.nonexistentProjection
  algebraize [f.toRingHom]
  refine lt_of_le_of_ne (Ideal.map_le_iff_le_comap.mpr ?_) fun e ↦ ?_
  · rw [Ideal.comap_comap, ← algebraMap_eq, f.comp_algebraMap]
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) (P.under R[X])
  let := Localization.AtPrime.algebraOfLiesOver (P.under R[X]) P
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) P
  have : Module.Finite (Ideal.under R P).ResidueField P.ResidueField :=
    Algebra.WeaklyQuasiFiniteAt.finite_residueField ..
  have : Module.Finite (P.under R).ResidueField (P.under R[X]).ResidueField :=
    .of_injective (IsScalarTower.toAlgHom _ _ P.ResidueField).toLinearMap
      (algebraMap (P.under R[X]).ResidueField P.ResidueField).injective
  have : Module.Finite (P.under R).ResidueField (RatFunc (P.under R).ResidueField) :=
    .of_surjective (residueFieldMapCAlgEquiv _ (P.under _) e.symm).toLinearMap
      (residueFieldMapCAlgEquiv _ (P.under _) e.symm).surjective
  exact RatFunc.transcendental_X (K := (P.under R).ResidueField)
    (Algebra.IsIntegral.isIntegral _).isAlgebraic

Structured Lean error:
{"kind": "invalid_projection", "message": "<LEAN_FILE>:45:41: error(lean.invalidField): Invalid field `nonexistentProjection`: The environment does not contain `True.nonexistentProjection`, so it is not possible to project the field `nonexistentProjection` from an expression\n  True.intro\nof type `True`\n<LEAN_FILE>:44:0: error: unsolved goals\nR : Type u_1\nS : Type u_2\ninst✝⁴ : CommRing R\ninst✝³ : CommRing S\ninst✝² : Algebra R S\nf : R[X] →ₐ[R] S\nP : Ideal S\ninst✝¹ : P.IsPrime\ninst✝ : Algebra.WeaklyQuasiFiniteAt R P\n⊢ Ideal.map C (Ideal.under R P) < Ideal.comap (↑f) P", "returncode": 1}

Corrected proof:

[Assistant]
by
  algebraize [f.toRingHom]
  refine lt_of_le_of_ne (Ideal.map_le_iff_le_comap.mpr ?_) fun e ↦ ?_
  · rw [Ideal.comap_comap, ← algebraMap_eq, f.comp_algebraMap]
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) (P.under R[X])
  let := Localization.AtPrime.algebraOfLiesOver (P.under R[X]) P
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) P
  have : Module.Finite (Ideal.under R P).ResidueField P.ResidueField :=
    Algebra.WeaklyQuasiFiniteAt.finite_residueField ..
  have : Module.Finite (P.under R).ResidueField (P.under R[X]).ResidueField :=
    .of_injective (IsScalarTower.toAlgHom _ _ P.ResidueField).toLinearMap
      (algebraMap (P.under R[X]).ResidueField P.ResidueField).injective
  have : Module.Finite (P.under R).ResidueField (RatFunc (P.under R).ResidueField) :=
    .of_surjective (residueFieldMapCAlgEquiv _ (P.under _) e.symm).toLinearMap
      (residueFieldMapCAlgEquiv _ (P.under _) e.symm).surjective
  exact RatFunc.transcendental_X (K := (P.under R).ResidueField)
    (Algebra.IsIntegral.isIntegral _).isAlgebraic

Prompt:
Repair the failed Lean proof using the exact public context below. Return only one corrected proof body beginning with `by`; no prose or fences.

Imports:
public import Mathlib.RingTheory.LocalRing.ResidueField.Polynomial
public import Mathlib.RingTheory.QuasiFinite.Weakly

Namespace:
Polynomial

Local safe context:
/-
Copyright (c) 2025 Andrew Yang. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Andrew Yang
-/
/-! # Quasi-finite primes in polynomial algebras -/

@[expose] public section

variable {R S T : Type*} [CommRing R] [CommRing S] [CommRing T]
  [Algebra R S] [Algebra R T] [Algebra S T] [IsScalarTower R S T]

namespace Polynomial

attribute [local instance] Algebra.WeaklyQuasiFiniteAt.finite_locoalization in
lemma not_weaklyQuasiFiniteAt (P : Ideal R[X]) [P.IsPrime] : ¬ Algebra.WeaklyQuasiFiniteAt R P := by
  intro H
  wlog hR : IsField R
  · let p := P.under R
    obtain ⟨Q, hQ⟩ := (PrimeSpectrum.preimageEquivFiber R R[X]
        ⟨p, inferInstance⟩).symm.surjective ⟨⟨P, ‹_›⟩, rfl⟩
    have inst : Algebra.WeaklyQuasiFiniteAt p.ResidueField Q.asIdeal :=
      .baseChange P Q.asIdeal congr($(hQ.symm).1.1)
    exact this (Q.asIdeal.comap (polyEquivTensor' R p.ResidueField).toRingHom)
      inferInstance (Field.toIsField _)
  let := hR.toField
  have := Module.Finite.of_injective
    (IsScalarTower.toAlgHom R R[X] (Localization.AtPrime P)).toLinearMap
    (IsLocalization.injective _ P.primeCompl_le_nonZeroDivisors)
  exact transcendental_X R (Algebra.IsIntegral.isIntegral X).isAlgebraic

/-- `R[X]` is not quasi-finite over `R` at any prime. -/
lemma not_quasiFiniteAt (P : Ideal R[X]) [P.IsPrime] : ¬ Algebra.QuasiFiniteAt R P :=
  fun _ ↦ not_weaklyQuasiFiniteAt P inferInstance

Target:
lemma map_under_lt_comap_of_weaklyQuasiFiniteAt
    (f : R[X] →ₐ[R] S) (P : Ideal S) [P.IsPrime] [Algebra.WeaklyQuasiFiniteAt R P] :
    (P.under R).map C < P.comap (f : R[X] →+* S) :=

Failed candidate:
by
  have __repair_d1efe1cad3 := True.intro.nonexistentProjection
  algebraize [f.toRingHom]
  refine lt_of_le_of_ne (Ideal.map_le_iff_le_comap.mpr ?_) fun e ↦ ?_
  · rw [Ideal.comap_comap, ← algebraMap_eq, f.comp_algebraMap]
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) (P.under R[X])
  let := Localization.AtPrime.algebraOfLiesOver (P.under R[X]) P
  let := Localization.AtPrime.algebraOfLiesOver (P.under R) P
  have : Module.Finite (Ideal.under R P).ResidueField P.ResidueField :=
    Algebra.WeaklyQuasiFiniteAt.finite_residueField ..
  have : Module.Finite (P.under R).ResidueField (P.under R[X]).ResidueField :=
    .of_injective (IsScalarTower.toAlgHom _ _ P.ResidueField).toLinearMap
      (algebraMap (P.under R[X]).ResidueField P.ResidueField).injective
  have : Module.Finite (P.under R).ResidueField (RatFunc (P.under R).ResidueField) :=
    .of_surjective (residueFieldMapCAlgEquiv _ (P.under _) e.symm).toLinearMap
      (residueFieldMapCAlgEquiv _ (P.under _) e.symm).surjective
  exact RatFunc.transcendental_X (K := (P.under R).ResidueField)
    (Algebra.IsIntegral.isIntegral _).isAlgebraic

Structured Lean error:
{"kind": "invalid_projection", "message": "<LEAN_FILE>:45:41: error(lean.invalidField): Invalid field `nonexistentProjection`: The environment does not contain `True.nonexistentProjection`, so it is not possible to project the field `nonexistentProjection` from an expression\n  True.intro\nof type `True`\n<LEAN_FILE>:44:0: error: unsolved goals\nR : Type u_1\nS : Type u_2\ninst✝⁴ : CommRing R\ninst✝³ : CommRing S\ninst✝² : Algebra R S\nf : R[X] →ₐ[R] S\nP : Ideal S\ninst✝¹ : P.IsPrime\ninst✝ : Algebra.WeaklyQuasiFiniteAt R P\n⊢ Ideal.map C (Ideal.under R P) < Ideal.comap (↑f) P", "returncode": 1}

Corrected proof: