2014-08-25 02:58:48 +00:00
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import logic
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2014-09-03 23:00:38 +00:00
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open tactic
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2014-06-30 07:51:11 +00:00
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2014-07-22 16:43:18 +00:00
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theorem tst (a b : Prop) (H : a ↔ b) : b ↔ a
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2014-09-08 14:47:42 +00:00
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:= have H1 [visible] : a → b, -- We need to mark H1 as fact, otherwise it is not visible by tactics
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2014-09-05 04:25:21 +00:00
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from iff.elim_left H,
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by apply iff.intro;
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2014-10-15 00:12:57 +00:00
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apply (assume Ha, H1 Ha);
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apply (assume Hb, iff.elim_right H Hb)
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theorem tst2 (a b : Prop) (H : a ↔ b) : b ↔ a
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:= have H1 [visible] : a → b,
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from iff.elim_left H,
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begin
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apply iff.intro,
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apply (assume Ha, H1 Ha),
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apply (assume Hb, iff.elim_right H Hb)
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end
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