Let x0 of type ο be given.
Let x1 of type ο be given.
Assume H0: x0.
Assume H1: x1.
Apply and_def with
λ x2 x3 : ο → ο → ο . x3 x0 x1.
Let x2 of type ο be given.
Assume H2: x0 ⟶ x1 ⟶ x2.
Apply H2 leaving 2 subgoals.
The subproof is completed by applying H0.
The subproof is completed by applying H1.