Let x0 of type ι be given.
Let x1 of type ι → ι → ο be given.
Let x2 of type ι be given.
Apply unknownprop_842e3a59c950354fe992f35e06c72f1494393d706434db72016878dac5e106af with
dd3c8.. x0 x1 x2,
x0,
x1,
x2.
Let x3 of type ι → ι → ο be given.
The subproof is completed by applying H0.