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sq_pos_iff (a : R) : 0 < a ^ 2 ↔ a ≠ 0
pow_bit0_pos_iff a one_ne_zero
theorem
sq_pos_iff
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "one_ne_zero", "pow_bit0_pos_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_abs (x : R) : |x| ^ 2 = x ^ 2
by simpa only [sq] using abs_mul_abs_self x
theorem
sq_abs
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_mul_abs_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_sq (x : R) : |x ^ 2| = x ^ 2
by simpa only [sq] using abs_mul_self x
theorem
abs_sq
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_mul_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_lt_sq : x ^ 2 < y ^ 2 ↔ |x| < |y|
by simpa only [sq_abs] using (@strict_mono_on_pow R _ _ two_pos).lt_iff_lt (abs_nonneg x) (abs_nonneg y)
theorem
sq_lt_sq
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_nonneg", "sq_abs", "strict_mono_on_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_lt_sq' (h1 : -y < x) (h2 : x < y) : x ^ 2 < y ^ 2
sq_lt_sq.2 (lt_of_lt_of_le (abs_lt.2 ⟨h1, h2⟩) (le_abs_self _))
theorem
sq_lt_sq'
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "le_abs_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_le_sq : x ^ 2 ≤ y ^ 2 ↔ |x| ≤ |y|
by simpa only [sq_abs] using (@strict_mono_on_pow R _ _ two_pos).le_iff_le (abs_nonneg x) (abs_nonneg y)
theorem
sq_le_sq
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_nonneg", "sq_abs", "strict_mono_on_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_le_sq' (h1 : -y ≤ x) (h2 : x ≤ y) : x ^ 2 ≤ y ^ 2
sq_le_sq.2 (le_trans (abs_le.mpr ⟨h1, h2⟩) (le_abs_self _))
theorem
sq_le_sq'
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "le_abs_self" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_lt_of_sq_lt_sq (h : x^2 < y^2) (hy : 0 ≤ y) : |x| < y
by rwa [← abs_of_nonneg hy, ← sq_lt_sq]
theorem
abs_lt_of_sq_lt_sq
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_of_nonneg", "sq_lt_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_lt_of_sq_lt_sq' (h : x^2 < y^2) (hy : 0 ≤ y) : -y < x ∧ x < y
abs_lt.mp $ abs_lt_of_sq_lt_sq h hy
theorem
abs_lt_of_sq_lt_sq'
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_lt_of_sq_lt_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_le_of_sq_le_sq (h : x^2 ≤ y^2) (hy : 0 ≤ y) : |x| ≤ y
by rwa [← abs_of_nonneg hy, ← sq_le_sq]
theorem
abs_le_of_sq_le_sq
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_of_nonneg", "sq_le_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
abs_le_of_sq_le_sq' (h : x^2 ≤ y^2) (hy : 0 ≤ y) : -y ≤ x ∧ x ≤ y
abs_le.mp $ abs_le_of_sq_le_sq h hy
theorem
abs_le_of_sq_le_sq'
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_le_of_sq_le_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_eq_sq_iff_abs_eq_abs (x y : R) : x^2 = y^2 ↔ |x| = |y|
by simp only [le_antisymm_iff, sq_le_sq]
lemma
sq_eq_sq_iff_abs_eq_abs
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "sq_le_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_le_one_iff_abs_le_one (x : R) : x^2 ≤ 1 ↔ |x| ≤ 1
by simpa only [one_pow, abs_one] using @sq_le_sq _ _ x 1
lemma
sq_le_one_iff_abs_le_one
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_one", "one_pow", "sq_le_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_lt_one_iff_abs_lt_one (x : R) : x^2 < 1 ↔ |x| < 1
by simpa only [one_pow, abs_one] using @sq_lt_sq _ _ x 1
lemma
sq_lt_one_iff_abs_lt_one
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_one", "one_pow", "sq_lt_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
one_le_sq_iff_one_le_abs (x : R) : 1 ≤ x^2 ↔ 1 ≤ |x|
by simpa only [one_pow, abs_one] using @sq_le_sq _ _ 1 x
lemma
one_le_sq_iff_one_le_abs
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_one", "one_pow", "sq_le_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
one_lt_sq_iff_one_lt_abs (x : R) : 1 < x^2 ↔ 1 < |x|
by simpa only [one_pow, abs_one] using @sq_lt_sq _ _ 1 x
lemma
one_lt_sq_iff_one_lt_abs
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "abs_one", "one_pow", "sq_lt_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_four_le_pow_two_of_pow_two_le {x y : R} (h : x^2 ≤ y) : x^4 ≤ y^2
(pow_mul x 2 2).symm ▸ pow_le_pow_of_le_left (sq_nonneg x) h 2
lemma
pow_four_le_pow_two_of_pow_two_le
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "pow_le_pow_of_le_left", "pow_mul", "sq_nonneg" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
two_mul_le_add_sq (a b : R) : 2 * a * b ≤ a ^ 2 + b ^ 2
sub_nonneg.mp ((sub_add_eq_add_sub _ _ _).subst ((sub_sq a b).subst (sq_nonneg _)))
lemma
two_mul_le_add_sq
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "sq_nonneg", "sub_sq" ]
Arithmetic mean-geometric mean (AM-GM) inequality for linearly ordered commutative rings.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_pos_iff (hn : 0 < n) : 0 < a ^ n ↔ 0 < a
by simp_rw [zero_lt_iff, pow_ne_zero_iff hn]
lemma
pow_pos_iff
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "pow_ne_zero_iff", "zero_lt_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_lt_pow_succ (ha : 1 < a) : a ^ n < a ^ n.succ
by { rw [←one_mul (a ^ n), pow_succ], exact mul_lt_right₀ _ ha (pow_ne_zero _ (zero_lt_one.trans ha).ne') }
lemma
pow_lt_pow_succ
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "mul_lt_right₀", "pow_ne_zero", "pow_succ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_lt_pow₀ (ha : 1 < a) (hmn : m < n) : a ^ m < a ^ n
by { induction hmn with n hmn ih, exacts [pow_lt_pow_succ ha, lt_trans ih (pow_lt_pow_succ ha)] }
lemma
pow_lt_pow₀
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "ih", "pow_lt_pow_succ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_neg_one : f (-1) = 1
(pow_eq_one_iff (nat.succ_ne_zero 1)).1 $ by rw [←map_pow, neg_one_sq, map_one]
lemma
monoid_hom.map_neg_one
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "map_one", "neg_one_sq", "pow_eq_one_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_neg (x : R) : f (-x) = f x
by rw [←neg_one_mul, map_mul, map_neg_one, one_mul]
lemma
monoid_hom.map_neg
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[ "map_mul", "one_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
map_sub_swap (x y : R) : f (x - y) = f (y - x)
by rw [←map_neg, neg_sub]
lemma
monoid_hom.map_sub_swap
algebra.group_power
src/algebra/group_power/order.lean
[ "algebra.order.ring.abs", "algebra.order.with_zero", "algebra.group_power.ring", "data.set.intervals.basic" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_pow : ∀ {n : ℕ}, 0 < n → (0 : M) ^ n = 0
| (n+1) _ := by rw [pow_succ, zero_mul]
lemma
zero_pow
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "pow_succ", "zero_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_pow' : ∀ n : ℕ, n ≠ 0 → (0 : M) ^ n = 0
| 0 h := absurd rfl h | (k+1) h := by { rw [pow_succ], exact zero_mul _ }
lemma
zero_pow'
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "pow_succ", "zero_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_pow_eq (n : ℕ) : (0 : M)^n = if n = 0 then 1 else 0
begin split_ifs with h, { rw [h, pow_zero], }, { rw [zero_pow (nat.pos_of_ne_zero h)] }, end
lemma
zero_pow_eq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "pow_zero", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_eq_zero_of_le {x : M} {n m : ℕ} (hn : n ≤ m) (hx : x^n = 0) : x^m = 0
by rw [← tsub_add_cancel_of_le hn, pow_add, hx, mul_zero]
lemma
pow_eq_zero_of_le
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "mul_zero", "pow_add", "tsub_add_cancel_of_le" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_eq_zero [no_zero_divisors M] {x : M} {n : ℕ} (H : x^n = 0) : x = 0
begin induction n with n ih, { rw pow_zero at H, rw [← mul_one x, H, mul_zero] }, { rw pow_succ at H, exact or.cases_on (mul_eq_zero.1 H) id ih } end
theorem
pow_eq_zero
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "ih", "mul_one", "mul_zero", "no_zero_divisors", "pow_succ", "pow_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_eq_zero_iff [no_zero_divisors M] {a : M} {n : ℕ} (hn : 0 < n) : a ^ n = 0 ↔ a = 0
begin refine ⟨pow_eq_zero, _⟩, rintros rfl, exact zero_pow hn, end
lemma
pow_eq_zero_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "no_zero_divisors", "zero_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_eq_zero_iff' [no_zero_divisors M] [nontrivial M] {a : M} {n : ℕ} : a ^ n = 0 ↔ a = 0 ∧ n ≠ 0
by cases (zero_le n).eq_or_gt; simp [*, ne_of_gt]
lemma
pow_eq_zero_iff'
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "no_zero_divisors", "nontrivial" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_ne_zero_iff [no_zero_divisors M] {a : M} {n : ℕ} (hn : 0 < n) : a ^ n ≠ 0 ↔ a ≠ 0
(pow_eq_zero_iff hn).not
lemma
pow_ne_zero_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "no_zero_divisors", "pow_eq_zero_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ne_zero_pow {a : M} {n : ℕ} (hn : n ≠ 0) : a ^ n ≠ 0 → a ≠ 0
by { contrapose!, rintro rfl, exact zero_pow' n hn }
lemma
ne_zero_pow
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "zero_pow'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_ne_zero [no_zero_divisors M] {a : M} (n : ℕ) (h : a ≠ 0) : a ^ n ≠ 0
mt pow_eq_zero h
theorem
pow_ne_zero
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "no_zero_divisors", "pow_eq_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ne_zero.pow [no_zero_divisors M] {x : M} [ne_zero x] {n : ℕ} : ne_zero (x ^ n)
⟨pow_ne_zero n ne_zero.out⟩
instance
ne_zero.pow
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "ne_zero", "no_zero_divisors" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_eq_zero_iff [no_zero_divisors M] {a : M} : a ^ 2 = 0 ↔ a = 0
pow_eq_zero_iff two_pos
theorem
sq_eq_zero_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "no_zero_divisors", "pow_eq_zero_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_pow_eq_zero [nontrivial M] {n : ℕ} : (0 : M) ^ n = 0 ↔ 0 < n
begin split; intro h, { rw [pos_iff_ne_zero], rintro rfl, simpa using h }, { exact zero_pow' n h.ne.symm } end
lemma
zero_pow_eq_zero
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "nontrivial", "zero_pow'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ring.inverse_pow (r : M) : ∀ (n : ℕ), ring.inverse r ^ n = ring.inverse (r ^ n)
| 0 := by rw [pow_zero, pow_zero, ring.inverse_one] | (n + 1) := by rw [pow_succ, pow_succ', ring.mul_inverse_rev' ((commute.refl r).pow_left n), ring.inverse_pow]
lemma
ring.inverse_pow
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "commute.refl", "pow_succ", "pow_succ'", "pow_zero", "ring.inverse", "ring.inverse_one", "ring.mul_inverse_rev'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_monoid_with_zero_hom : M →*₀ M
{ map_zero' := zero_pow hn, ..pow_monoid_hom n }
def
pow_monoid_with_zero_hom
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "pow_monoid_hom", "zero_pow" ]
We define `x ↦ x^n` (for positive `n : ℕ`) as a `monoid_with_zero_hom`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
coe_pow_monoid_with_zero_hom : (pow_monoid_with_zero_hom hn : M → M) = (^ n)
rfl
lemma
coe_pow_monoid_with_zero_hom
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "pow_monoid_with_zero_hom" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_monoid_with_zero_hom_apply (a : M) : pow_monoid_with_zero_hom hn a = a ^ n
rfl
lemma
pow_monoid_with_zero_hom_apply
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "pow_monoid_with_zero_hom" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
pow_dvd_pow_iff [cancel_comm_monoid_with_zero R] {x : R} {n m : ℕ} (h0 : x ≠ 0) (h1 : ¬ is_unit x) : x ^ n ∣ x ^ m ↔ n ≤ m
begin split, { intro h, rw [← not_lt], intro hmn, apply h1, have : x ^ m * x ∣ x ^ m * 1, { rw [← pow_succ', mul_one], exact (pow_dvd_pow _ (nat.succ_le_of_lt hmn)).trans h }, rwa [mul_dvd_mul_iff_left, ← is_unit_iff_dvd_one] at this, apply pow_ne_zero m h0 }, { apply pow_dvd_pow } end
lemma
pow_dvd_pow_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "cancel_comm_monoid_with_zero", "is_unit", "is_unit_iff_dvd_one", "mul_dvd_mul_iff_left", "mul_one", "pow_dvd_pow", "pow_ne_zero", "pow_succ'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ring_hom.map_pow (f : R →+* S) (a) : ∀ n : ℕ, f (a ^ n) = (f a) ^ n
map_pow f a
lemma
ring_hom.map_pow
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "map_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
min_pow_dvd_add {n m : ℕ} {a b c : R} (ha : c ^ n ∣ a) (hb : c ^ m ∣ b) : c ^ (min n m) ∣ a + b
begin replace ha := (pow_dvd_pow c (min_le_left n m)).trans ha, replace hb := (pow_dvd_pow c (min_le_right n m)).trans hb, exact dvd_add ha hb end
lemma
min_pow_dvd_add
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "dvd_add", "pow_dvd_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_sq (a b : R) : (a + b) ^ 2 = a ^ 2 + 2 * a * b + b ^ 2
by simp only [sq, add_mul_self_eq]
lemma
add_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "add_mul_self_eq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
add_sq' (a b : R) : (a + b) ^ 2 = a ^ 2 + b ^ 2 + 2 * a * b
by rw [add_sq, add_assoc, add_comm _ (b ^ 2), add_assoc]
lemma
add_sq'
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "add_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_one_pow_eq_or : ∀ n : ℕ, (-1 : R)^n = 1 ∨ (-1 : R)^n = -1
| 0 := or.inl (pow_zero _) | (n+1) := (neg_one_pow_eq_or n).swap.imp (λ h, by rw [pow_succ, h, neg_one_mul, neg_neg]) (λ h, by rw [pow_succ, h, mul_one])
theorem
neg_one_pow_eq_or
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "mul_one", "neg_one_mul", "pow_succ", "pow_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_pow (a : R) (n : ℕ) : (- a) ^ n = (-1) ^ n * a ^ n
(neg_one_mul a) ▸ (commute.neg_one_left a).mul_pow n
theorem
neg_pow
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "commute.neg_one_left", "mul_pow", "neg_one_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_pow_bit0 (a : R) (n : ℕ) : (- a) ^ (bit0 n) = a ^ (bit0 n)
by rw [pow_bit0', neg_mul_neg, pow_bit0']
theorem
neg_pow_bit0
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "neg_mul_neg", "pow_bit0'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_pow_bit1 (a : R) (n : ℕ) : (- a) ^ (bit1 n) = - a ^ (bit1 n)
by simp only [bit1, pow_succ, neg_pow_bit0, neg_mul_eq_neg_mul]
theorem
neg_pow_bit1
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "neg_mul_eq_neg_mul", "neg_pow_bit0", "pow_succ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_sq (a : R) : (-a) ^ 2 = a ^ 2
by simp [sq]
lemma
neg_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_one_sq : (-1 : R) ^ 2 = 1
by rw [neg_sq, one_pow]
lemma
neg_one_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "neg_sq", "one_pow" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
commute.sq_sub_sq (h : commute a b) : a ^ 2 - b ^ 2 = (a + b) * (a - b)
by rw [sq, sq, h.mul_self_sub_mul_self_eq]
lemma
commute.sq_sub_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "commute" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
neg_one_pow_mul_eq_zero_iff {n : ℕ} {r : R} : (-1)^n * r = 0 ↔ r = 0
by rcases neg_one_pow_eq_or R n; simp [h]
lemma
neg_one_pow_mul_eq_zero_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "neg_one_pow_eq_or" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_neg_one_pow_eq_zero_iff {n : ℕ} {r : R} : r * (-1)^n = 0 ↔ r = 0
by rcases neg_one_pow_eq_or R n; simp [h]
lemma
mul_neg_one_pow_eq_zero_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "neg_one_pow_eq_or" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
commute.sq_eq_sq_iff_eq_or_eq_neg (h : commute a b) : a ^ 2 = b ^ 2 ↔ a = b ∨ a = -b
by rw [←sub_eq_zero, h.sq_sub_sq, mul_eq_zero, add_eq_zero_iff_eq_neg, sub_eq_zero, or_comm]
lemma
commute.sq_eq_sq_iff_eq_or_eq_neg
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "commute", "mul_eq_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_eq_one_iff : a^2 = 1 ↔ a = 1 ∨ a = -1
by rw [←(commute.one_right a).sq_eq_sq_iff_eq_or_eq_neg, one_pow]
lemma
sq_eq_one_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "commute.one_right", "one_pow", "sq_eq_sq_iff_eq_or_eq_neg" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_ne_one_iff : a^2 ≠ 1 ↔ a ≠ 1 ∧ a ≠ -1
sq_eq_one_iff.not.trans not_or_distrib
lemma
sq_ne_one_iff
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "not_or_distrib" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_sub_sq (a b : R) : a ^ 2 - b ^ 2 = (a + b) * (a - b)
(commute.all a b).sq_sub_sq
lemma
sq_sub_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "commute.all" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sub_sq (a b : R) : (a - b) ^ 2 = a ^ 2 - 2 * a * b + b ^ 2
by rw [sub_eq_add_neg, add_sq, neg_sq, mul_neg, ← sub_eq_add_neg]
lemma
sub_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "add_sq", "mul_neg", "neg_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sub_sq' (a b : R) : (a - b) ^ 2 = a ^ 2 + b ^ 2 - 2 * a * b
by rw [sub_eq_add_neg, add_sq', neg_sq, mul_neg, ← sub_eq_add_neg]
lemma
sub_sq'
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "add_sq'", "mul_neg", "neg_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_eq_sq_iff_eq_or_eq_neg : a ^ 2 = b ^ 2 ↔ a = b ∨ a = -b
(commute.all a b).sq_eq_sq_iff_eq_or_eq_neg
lemma
sq_eq_sq_iff_eq_or_eq_neg
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "commute.all" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_or_eq_neg_of_sq_eq_sq (a b : R) : a ^ 2 = b ^ 2 → a = b ∨ a = -b
sq_eq_sq_iff_eq_or_eq_neg.1
lemma
eq_or_eq_neg_of_sq_eq_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
sq_eq_sq_iff_eq_or_eq_neg {a b : Rˣ} : a ^ 2 = b ^ 2 ↔ a = b ∨ a = -b
by simp_rw [ext_iff, coe_pow, sq_eq_sq_iff_eq_or_eq_neg, units.coe_neg]
lemma
units.sq_eq_sq_iff_eq_or_eq_neg
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "sq_eq_sq_iff_eq_or_eq_neg", "units.coe_neg" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_or_eq_neg_of_sq_eq_sq (a b : Rˣ) (h : a ^ 2 = b ^ 2) : a = b ∨ a = -b
units.sq_eq_sq_iff_eq_or_eq_neg.1 h
lemma
units.eq_or_eq_neg_of_sq_eq_sq
algebra.group_power
src/algebra/group_power/ring.lean
[ "algebra.group_power.basic", "algebra.group_with_zero.commute", "algebra.hom.ring", "algebra.ring.commute", "algebra.group_with_zero.divisibility", "algebra.ring.divisibility", "data.nat.order.basic" ]
[ "eq_or_eq_neg_of_sq_eq_sq" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_semiring_action (M : Type u) (R : Type v) [monoid M] [semiring R] extends distrib_mul_action M R
(smul_one : ∀ (g : M), (g • 1 : R) = 1) (smul_mul : ∀ (g : M) (x y : R), g • (x * y) = (g • x) * (g • y))
class
mul_semiring_action
algebra.group_ring_action
src/algebra/group_ring_action/basic.lean
[ "algebra.ring.equiv", "algebra.field.defs", "group_theory.group_action.group" ]
[ "distrib_mul_action", "monoid", "semiring" ]
Typeclass for multiplicative actions by monoids on semirings. This combines `distrib_mul_action` with `mul_distrib_mul_action`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_semiring_action.to_mul_distrib_mul_action [h : mul_semiring_action M R] : mul_distrib_mul_action M R
{ ..h }
instance
mul_semiring_action.to_mul_distrib_mul_action
algebra.group_ring_action
src/algebra/group_ring_action/basic.lean
[ "algebra.ring.equiv", "algebra.field.defs", "group_theory.group_action.group" ]
[ "mul_distrib_mul_action", "mul_semiring_action" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_semiring_action.to_ring_hom [mul_semiring_action M R] (x : M) : R →+* R
{ .. mul_distrib_mul_action.to_monoid_hom R x, .. distrib_mul_action.to_add_monoid_hom R x }
def
mul_semiring_action.to_ring_hom
algebra.group_ring_action
src/algebra/group_ring_action/basic.lean
[ "algebra.ring.equiv", "algebra.field.defs", "group_theory.group_action.group" ]
[ "distrib_mul_action.to_add_monoid_hom", "mul_distrib_mul_action.to_monoid_hom", "mul_semiring_action" ]
Each element of the monoid defines a semiring homomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
to_ring_hom_injective [mul_semiring_action M R] [has_faithful_smul M R] : function.injective (mul_semiring_action.to_ring_hom M R)
λ m₁ m₂ h, eq_of_smul_eq_smul $ λ r, ring_hom.ext_iff.1 h r
theorem
to_ring_hom_injective
algebra.group_ring_action
src/algebra/group_ring_action/basic.lean
[ "algebra.ring.equiv", "algebra.field.defs", "group_theory.group_action.group" ]
[ "has_faithful_smul", "mul_semiring_action", "mul_semiring_action.to_ring_hom" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_semiring_action.to_ring_equiv [mul_semiring_action G R] (x : G) : R ≃+* R
{ .. distrib_mul_action.to_add_equiv R x, .. mul_semiring_action.to_ring_hom G R x }
def
mul_semiring_action.to_ring_equiv
algebra.group_ring_action
src/algebra/group_ring_action/basic.lean
[ "algebra.ring.equiv", "algebra.field.defs", "group_theory.group_action.group" ]
[ "distrib_mul_action.to_add_equiv", "mul_semiring_action", "mul_semiring_action.to_ring_hom" ]
Each element of the group defines a semiring isomorphism.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_semiring_action.comp_hom (f : N →* M) [mul_semiring_action M R] : mul_semiring_action N R
{ smul := has_smul.comp.smul f, ..distrib_mul_action.comp_hom R f, ..mul_distrib_mul_action.comp_hom R f }
def
mul_semiring_action.comp_hom
algebra.group_ring_action
src/algebra/group_ring_action/basic.lean
[ "algebra.ring.equiv", "algebra.field.defs", "group_theory.group_action.group" ]
[ "distrib_mul_action.comp_hom", "has_smul.comp.smul", "mul_distrib_mul_action.comp_hom", "mul_semiring_action" ]
Compose a `mul_semiring_action` with a `monoid_hom`, with action `f r' • m`. See note [reducible non-instances].
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
smul_inv'' [mul_semiring_action M F] (x : M) (m : F) : x • m⁻¹ = (x • m)⁻¹
map_inv₀ (mul_semiring_action.to_ring_hom M F x) _
lemma
smul_inv''
algebra.group_ring_action
src/algebra/group_ring_action/basic.lean
[ "algebra.ring.equiv", "algebra.field.defs", "group_theory.group_action.group" ]
[ "map_inv₀", "mul_semiring_action", "mul_semiring_action.to_ring_hom" ]
Note that `smul_inv'` refers to the group case, and `smul_inv` has an additional inverse on `x`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_invariant_subring : Prop
(smul_mem : ∀ (m : M) {x : R}, x ∈ S → m • x ∈ S)
class
is_invariant_subring
algebra.group_ring_action
src/algebra/group_ring_action/invariant.lean
[ "algebra.hom.group_action", "ring_theory.subring.pointwise" ]
[]
A typeclass for subrings invariant under a `mul_semiring_action`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_invariant_subring.to_mul_semiring_action [is_invariant_subring M S] : mul_semiring_action M S
{ smul := λ m x, ⟨m • x, is_invariant_subring.smul_mem m x.2⟩, one_smul := λ s, subtype.eq $ one_smul M s, mul_smul := λ m₁ m₂ s, subtype.eq $ mul_smul m₁ m₂ s, smul_add := λ m s₁ s₂, subtype.eq $ smul_add m s₁ s₂, smul_zero := λ m, subtype.eq $ smul_zero m, smul_one := λ m, subtype.eq $ smul_one m, smul_mu...
instance
is_invariant_subring.to_mul_semiring_action
algebra.group_ring_action
src/algebra/group_ring_action/invariant.lean
[ "algebra.hom.group_action", "ring_theory.subring.pointwise" ]
[ "is_invariant_subring", "mul_semiring_action", "one_smul", "smul_add", "smul_mul'", "smul_zero" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_invariant_subring.subtype_hom : U →+*[M] R'
{ map_smul' := λ m s, rfl, ..U.subtype }
def
is_invariant_subring.subtype_hom
algebra.group_ring_action
src/algebra/group_ring_action/invariant.lean
[ "algebra.hom.group_action", "ring_theory.subring.pointwise" ]
[]
The canonical inclusion from an invariant subring.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_invariant_subring.coe_subtype_hom : (is_invariant_subring.subtype_hom M U : U → R') = coe
rfl
theorem
is_invariant_subring.coe_subtype_hom
algebra.group_ring_action
src/algebra/group_ring_action/invariant.lean
[ "algebra.hom.group_action", "ring_theory.subring.pointwise" ]
[ "is_invariant_subring.subtype_hom" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_invariant_subring.coe_subtype_hom' : (is_invariant_subring.subtype_hom M U : U →+* R') = U.subtype
rfl
theorem
is_invariant_subring.coe_subtype_hom'
algebra.group_ring_action
src/algebra/group_ring_action/invariant.lean
[ "algebra.hom.group_action", "ring_theory.subring.pointwise" ]
[ "is_invariant_subring.subtype_hom" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
submonoid.mul_semiring_action [mul_semiring_action M R] (H : submonoid M) : mul_semiring_action H R
{ smul := (•), .. H.mul_distrib_mul_action, .. H.distrib_mul_action }
instance
submonoid.mul_semiring_action
algebra.group_ring_action
src/algebra/group_ring_action/subobjects.lean
[ "algebra.group_ring_action.basic", "group_theory.subgroup.basic" ]
[ "mul_semiring_action", "submonoid" ]
A stronger version of `submonoid.distrib_mul_action`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
subgroup.mul_semiring_action [mul_semiring_action G R] (H : subgroup G) : mul_semiring_action H R
H.to_submonoid.mul_semiring_action
instance
subgroup.mul_semiring_action
algebra.group_ring_action
src/algebra/group_ring_action/subobjects.lean
[ "algebra.group_ring_action.basic", "group_theory.subgroup.basic" ]
[ "mul_semiring_action", "subgroup" ]
A stronger version of `subgroup.distrib_mul_action`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
left_ne_zero_of_mul : a * b ≠ 0 → a ≠ 0
mt (λ h, mul_eq_zero_of_left h b)
lemma
left_ne_zero_of_mul
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_eq_zero_of_left" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
right_ne_zero_of_mul : a * b ≠ 0 → b ≠ 0
mt (mul_eq_zero_of_right a)
lemma
right_ne_zero_of_mul
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_eq_zero_of_right" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
ne_zero_and_ne_zero_of_mul (h : a * b ≠ 0) : a ≠ 0 ∧ b ≠ 0
⟨left_ne_zero_of_mul h, right_ne_zero_of_mul h⟩
lemma
ne_zero_and_ne_zero_of_mul
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "right_ne_zero_of_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_eq_zero_of_ne_zero_imp_eq_zero {a b : M₀} (h : a ≠ 0 → b = 0) : a * b = 0
if ha : a = 0 then by rw [ha, zero_mul] else by rw [h ha, mul_zero]
lemma
mul_eq_zero_of_ne_zero_imp_eq_zero
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_zero", "zero_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_mul_eq_const : ((*) (0 : M₀)) = function.const _ 0
funext zero_mul
lemma
zero_mul_eq_const
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "zero_mul" ]
To match `one_mul_eq_id`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_zero_eq_const : (* (0 : M₀)) = function.const _ 0
funext mul_zero
lemma
mul_zero_eq_const
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_zero" ]
To match `mul_one_eq_id`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_zero_of_mul_self_eq_zero (h : a * a = 0) : a = 0
(eq_zero_or_eq_zero_of_mul_eq_zero h).elim id id
lemma
eq_zero_of_mul_self_eq_zero
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_ne_zero (ha : a ≠ 0) (hb : b ≠ 0) : a * b ≠ 0
mt eq_zero_or_eq_zero_of_mul_eq_zero $ not_or_distrib.mpr ⟨ha, hb⟩
theorem
mul_ne_zero
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul [has_zero M₀] [has_mul M₀] [no_zero_divisors M₀] {x y : M₀} [ne_zero x] [ne_zero y] : ne_zero (x * y)
⟨mul_ne_zero out out⟩
instance
ne_zero.mul
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "ne_zero", "no_zero_divisors" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_zero_of_zero_eq_one (h : (0 : M₀) = 1) (a : M₀) : a = 0
by rw [← mul_one a, ← h, mul_zero]
lemma
eq_zero_of_zero_eq_one
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_one", "mul_zero" ]
In a monoid with zero, if zero equals one, then zero is the only element.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
unique_of_zero_eq_one (h : (0 : M₀) = 1) : unique M₀
{ default := 0, uniq := eq_zero_of_zero_eq_one h }
def
unique_of_zero_eq_one
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "eq_zero_of_zero_eq_one", "unique" ]
In a monoid with zero, if zero equals one, then zero is the unique element. Somewhat arbitrarily, we define the default element to be `0`. All other elements will be provably equal to it, but not necessarily definitionally equal.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
subsingleton_iff_zero_eq_one : (0 : M₀) = 1 ↔ subsingleton M₀
⟨λ h, @unique.subsingleton _ (unique_of_zero_eq_one h), λ h, @subsingleton.elim _ h _ _⟩
theorem
subsingleton_iff_zero_eq_one
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "unique_of_zero_eq_one" ]
In a monoid with zero, zero equals one if and only if all elements of that semiring are equal.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
eq_of_zero_eq_one (h : (0 : M₀) = 1) (a b : M₀) : a = b
@subsingleton.elim _ (subsingleton_of_zero_eq_one h) a b
lemma
eq_of_zero_eq_one
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
zero_ne_one_or_forall_eq_0 : (0 : M₀) ≠ 1 ∨ (∀a:M₀, a = 0)
not_or_of_imp eq_zero_of_zero_eq_one
lemma
zero_ne_one_or_forall_eq_0
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "eq_zero_of_zero_eq_one", "not_or_of_imp" ]
In a monoid with zero, either zero and one are nonequal, or zero is the only element.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
left_ne_zero_of_mul_eq_one (h : a * b = 1) : a ≠ 0
left_ne_zero_of_mul $ ne_zero_of_eq_one h
lemma
left_ne_zero_of_mul_eq_one
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "left_ne_zero_of_mul", "ne_zero_of_eq_one" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
right_ne_zero_of_mul_eq_one (h : a * b = 1) : b ≠ 0
right_ne_zero_of_mul $ ne_zero_of_eq_one h
lemma
right_ne_zero_of_mul_eq_one
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "ne_zero_of_eq_one", "right_ne_zero_of_mul" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
cancel_monoid_with_zero.to_no_zero_divisors : no_zero_divisors M₀
⟨λ a b ab0, by { by_cases a = 0, { left, exact h }, right, apply cancel_monoid_with_zero.mul_left_cancel_of_ne_zero h, rw [ab0, mul_zero], }⟩
instance
cancel_monoid_with_zero.to_no_zero_divisors
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_zero", "no_zero_divisors" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_left_inj' (hc : c ≠ 0) : a * c = b * c ↔ a = b
(mul_left_injective₀ hc).eq_iff
lemma
mul_left_inj'
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_left_injective₀" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_right_inj' (ha : a ≠ 0) : a * b = a * c ↔ b = c
(mul_right_injective₀ ha).eq_iff
lemma
mul_right_inj'
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_right_injective₀" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_eq_mul_right_iff : a * c = b * c ↔ a = b ∨ c = 0
by by_cases hc : c = 0; [simp [hc], simp [mul_left_inj', hc]]
lemma
mul_eq_mul_right_iff
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_left_inj'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mul_eq_mul_left_iff : a * b = a * c ↔ b = c ∨ a = 0
by by_cases ha : a = 0; [simp [ha], simp [mul_right_inj', ha]]
lemma
mul_eq_mul_left_iff
algebra.group_with_zero
src/algebra/group_with_zero/basic.lean
[ "algebra.group.basic", "algebra.group_with_zero.defs", "algebra.group.order_synonym" ]
[ "mul_right_inj'" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83