lean2/tests/lean/run/tactic11.lean

18 lines
513 B
Text
Raw Normal View History

import logic
theorem tst (a b : Prop) (H : a ↔ b) : b ↔ a
:= have H1 [visible] : a → b, -- We need to mark H1 as fact, otherwise it is not visible by tactics
from iff.elim_left H,
by rapply iff.intro;
apply (assume Ha, H1 Ha);
apply (assume Hb, iff.elim_right H Hb)
theorem tst2 (a b : Prop) (H : a ↔ b) : b ↔ a
:= have H1 [visible] : a → b,
from iff.elim_left H,
begin
rapply iff.intro,
apply (assume Ha, H1 Ha),
apply (assume Hb, iff.elim_right H Hb)
end