Let x0 of type ι be given.
Let x1 of type (ι → ο) → ο be given.
Let x2 of type ι → ι → ι be given.
Let x3 of type ι → ι → ο be given.
Apply unknownprop_8fa6664b4fdc1f5674888568face8e12e8fad4e2404f2a75833970f8c56625c4 with
dd9fd.. x0 x1 x2 x3,
x0,
x1,
x2,
x3.
Let x4 of type ι → ι → ο be given.
The subproof is completed by applying H0.