@@ -18,16 +18,18 @@ universe u
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variable {α : Type u}
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- theorem nonzero_of_invertible [MulZeroOneClass α] (a : α) [Nontrivial α] [Invertible a] : a ≠ 0 :=
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+ theorem Invertible.ne_zero [MulZeroOneClass α] (a : α) [Nontrivial α] [Invertible a] : a ≠ 0 :=
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fun ha =>
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zero_ne_one <|
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calc
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0 = ⅟ a * a := by simp [ha]
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- _ = 1 := invOf_mul_self a
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+ _ = 1 := invOf_mul_self
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- instance (priority := 100 ) Invertible.ne_zero [MulZeroOneClass α] [Nontrivial α] (a : α)
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+ @[deprecated (since := "2024-08-15")] alias nonzero_of_invertible := Invertible.ne_zero
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+
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+ instance (priority := 100 ) Invertible.toNeZero [MulZeroOneClass α] [Nontrivial α] (a : α)
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[Invertible a] : NeZero a :=
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- ⟨nonzero_of_invertible a⟩
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+ ⟨Invertible.ne_zero a⟩
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section MonoidWithZero
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variable [MonoidWithZero α]
@@ -48,31 +50,31 @@ def invertibleOfNonzero {a : α} (h : a ≠ 0) : Invertible a :=
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@[simp]
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theorem invOf_eq_inv (a : α) [Invertible a] : ⅟ a = a⁻¹ :=
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- invOf_eq_right_inv (mul_inv_cancel₀ (nonzero_of_invertible a))
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+ invOf_eq_right_inv (mul_inv_cancel₀ (Invertible.ne_zero a))
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@[simp]
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theorem inv_mul_cancel_of_invertible (a : α) [Invertible a] : a⁻¹ * a = 1 :=
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- inv_mul_cancel₀ (nonzero_of_invertible a)
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+ inv_mul_cancel₀ (Invertible.ne_zero a)
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@[simp]
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theorem mul_inv_cancel_of_invertible (a : α) [Invertible a] : a * a⁻¹ = 1 :=
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- mul_inv_cancel₀ (nonzero_of_invertible a)
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+ mul_inv_cancel₀ (Invertible.ne_zero a)
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/-- `a` is the inverse of `a⁻¹` -/
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def invertibleInv {a : α} [Invertible a] : Invertible a⁻¹ :=
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⟨a, by simp, by simp⟩
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@[simp]
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theorem div_mul_cancel_of_invertible (a b : α) [Invertible b] : a / b * b = a :=
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- div_mul_cancel₀ a (nonzero_of_invertible b)
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+ div_mul_cancel₀ a (Invertible.ne_zero b)
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@[simp]
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theorem mul_div_cancel_of_invertible (a b : α) [Invertible b] : a * b / b = a :=
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- mul_div_cancel_right₀ a (nonzero_of_invertible b)
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+ mul_div_cancel_right₀ a (Invertible.ne_zero b)
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@[simp]
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theorem div_self_of_invertible (a : α) [Invertible a] : a / a = 1 :=
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- div_self (nonzero_of_invertible a)
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+ div_self (Invertible.ne_zero a)
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/-- `b / a` is the inverse of `a / b` -/
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def invertibleDiv (a b : α) [Invertible a] [Invertible b] : Invertible (a / b) :=
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