Let x0 of type ι be given.
Let x1 of type ι → ι → ι be given.
Let x2 of type ι → ι be given.
Apply unknownprop_947345c645b15afc187da1b271c8a12f66743a8acfe8a8fd8634e68c1d320314 with
971d3.. x0 x1 x2,
x0,
x1,
x2.
Let x3 of type ι → ι → ο be given.
The subproof is completed by applying H0.