2015-05-15 00:17:48 +00:00
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variable {A : Type}
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variable {f : A → A → A}
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variable {finv : A → A}
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premise (h : ∀ x y : A, finv (f x y) = y)
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2016-02-29 19:28:20 +00:00
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include h
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2015-05-15 00:17:48 +00:00
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theorem foo₁ : ∀ x y z : A, f x y = f x z → y = z :=
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2016-02-29 19:28:20 +00:00
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λ x y z, assume e, sorry
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2015-05-15 00:17:48 +00:00
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theorem foo₂ : ∀ x y z : A, f x y = f x z → y = z :=
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λ x y z, assume e,
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assert s₁ : finv (f x y) = finv (f x z), by rewrite e,
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2016-02-29 19:28:20 +00:00
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show y = z, by rewrite *h at s₁; exact s₁
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