11 lines
221 B
Text
11 lines
221 B
Text
exit
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import logic
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open tactic
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constant A : Type.{1}
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constant 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 (eq.subst H1);
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apply (eq.subst H2);
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apply eq.refl
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