Let x0 of type ο be given.
Let x1 of type ο be given.
Assume H1:
x0 ⟶ not x1 ⟶ False.
Assume H2:
not x0 ⟶ x1 ⟶ False.
Apply notE with
iff x0 x1 leaving 2 subgoals.
The subproof is completed by applying H0.
Apply unknownprop_a818f53272de918398012791887b763f90bf043f961a4f625d98076ca0b8b392 with
x0,
x1 leaving 2 subgoals.
Assume H3: x0.
Apply unknownprop_b777a79c17f16cd28153af063df26a4626b11c1f1d4394d7f537c11837ab0962 with
x1.
Apply H1 leaving 2 subgoals.
The subproof is completed by applying H3.
The subproof is completed by applying H4.
Assume H3: x1.
Apply unknownprop_b777a79c17f16cd28153af063df26a4626b11c1f1d4394d7f537c11837ab0962 with
x0.
Apply H2 leaving 2 subgoals.
The subproof is completed by applying H4.
The subproof is completed by applying H3.