Let x0 of type ι be given.
Let x1 of type ι → ι be given.
Let x2 of type ι → ι be given.
Let x3 of type ι → ο be given.
Apply unknownprop_90f58fc929469c4860e4ea70973e2dfc1b63b0a7d171f18500103ada7bbb21c5 with
7ba51.. x0 x1 x2 x3,
x0,
x1,
x2,
x3.
Let x4 of type ι → ι → ο be given.
The subproof is completed by applying H0.