2014-08-24 19:58:48 -07:00
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import logic
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2014-07-03 10:50:08 -07:00
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using tactic
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variable A : Type.{1}
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variable f : A → A → A
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theorem tst {a b c : A} (H1 : a = b) (H2 : b = c) : f a b = f b c
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:= by apply (@congr A A);
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apply (subst H2);
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apply refl;
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assumption
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