Let x0 of type ι be given.
Let x1 of type ι be given.
Let x2 of type ι be given.
Let x3 of type ι be given.
Apply unknownprop_71513a20f1177ff70329cea2acacdc027438e2c1b21157d461d18b1d34278a09 with
x0,
λ x4 . x1,
x2,
x3.
The subproof is completed by applying H0.