Let x0 of type ι be given.
Let x1 of type ι → ι → ο be given.
Let x2 of type ι → ο be given.
Let x3 of type ι be given.
Apply unknownprop_fd0c7809ab76ac9ed2ca8d335d900264a90f286e0b10ecc10f8eda78faa93454 with
e4ab3.. x0 x1 x2 x3,
x0,
x1,
x2,
x3.
Let x4 of type ι → ι → ο be given.
The subproof is completed by applying H0.