Let x0 of type ι be given.
Let x1 of type ι → ι → ο be given.
Let x2 of type ι → ι → ο be given.
Let x3 of type ι be given.
Apply unknownprop_b4bc53fcaaddef439b6308fecd5d9d4d5f1b52b358cb6217a9db144d5d06eb91 with
1f7e2.. x0 x1 x2 x3,
x0,
x1,
x2,
x3.
Let x4 of type ι → ι → ο be given.
The subproof is completed by applying H0.