Let x0 of type ι be given.
Let x1 of type ι → ι → ι be given.
Let x2 of type ι → ι → ι be given.
Let x3 of type ι → ι be given.
Apply unknownprop_85c9826e6bb0dfabdf6f30eeb1cda8dd3947275c40b466b4648c1a2973a44845 with
a255b.. x0 x1 x2 x3,
x0,
x1,
x2,
x3.
Let x4 of type ι → ι → ο be given.
The subproof is completed by applying H0.