Let x0 of type ι be given.
Let x1 of type ι → ο be given.
Let x2 of type ι → ο be given.
Assume H0:
∀ x3 . prim1 x3 x0 ⟶ iff (x1 x3) (x2 x3).
Apply unknownprop_b3f0546588eaaffbfada457a1b6c239e49888b4c546cfd7ac96a6a43fd9db95e with
x0,
x1,
x2.
The subproof is completed by applying H0.