lean2/tests/lean/run/tactic12.lean

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import standard
using tactic
theorem tst (a b : Prop) (H : ¬ a ¬ b) (Hb : b) : ¬ a ∧ b
:= by apply and_intro;
apply not_intro;
exact
(assume Ha, or_elim H
(assume Hna, absurd Ha Hna)
(assume Hnb, absurd Hb Hnb));
assumption