Let x0 of type ι be given.
Let x1 of type ι → ι → ο be given.
Let x2 of type ι → ι → ο be given.
Assume H0:
∀ x3 . prim1 x3 x0 ⟶ ∀ x4 . prim1 x4 x0 ⟶ iff (x1 x3 x4) (x2 x3 x4).
Apply unknownprop_75d5b46497f20dc30e2e5351a60197c4fa9d445bc23c6c8245597bb858180907 with
x0,
x1,
x2.
The subproof is completed by applying H0.