8 lines
200 B
Text
8 lines
200 B
Text
|
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)
|