12 lines
248 B
Text
12 lines
248 B
Text
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import standard
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using tactic
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theorem tst (a b : Bool) (H : ¬ a ∨ ¬ b) (Hb : b) : ¬ a ∧ b :=
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proof
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apply and_intro,
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apply not_intro,
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assume Ha, or_elim H
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(assume Hna, absurd Ha Hna)
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(assume Hnb, absurd Hb Hnb),
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assumption
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qed
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