lean2/tests/lean/run/tactic11.lean
Leonardo de Moura 8d584e54da feat(frontends/lean): add exact_apply
Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
2014-06-30 00:51:11 -07:00

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import logic
theorem tst (a b : Bool) (H : a ↔ b) : b ↔ a
:= have H1 [fact] : a → b, from iff_elim_left H,
by (apply iff_intro,
assume Hb, iff_mp_right H Hb,
assume Ha, H1 Ha)