Let x0 of type ι be given.
Let x1 of type ι → ο be given.
Apply H0 with
False.
Let x2 of type ι be given.
Apply H1 with
False.
Apply H3 with
False.
Apply H4 with
x1 x2 ⟶ False.
Assume H7: x1 x2.
Apply H6.
The subproof is completed by applying H7.