12 lines
308 B
Text
12 lines
308 B
Text
theorem not_f_eq_imp_eq
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: ¬∀{α β: Type} (f : α → β) a b, f a = f b → a = b := by
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intro h
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have : 1 = 2 := h (fun _ => 0) 1 2 rfl
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contradiction
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-- Counter-counterexample? (This is trivial.)
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theorem eq_imp_f_eq (f : α → β) (a b : α)
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: a = b → f a = f b := by
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intro h
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rw [h]
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