Let x0 of type ι be given.
Let x1 of type ι be given.
Let x2 of type ι be given.
Let x3 of type ι be given.
Apply unknownprop_65b697ce826092f2cc43df41585fc87a51cbb42f47ea078876e421084559202e with
x0,
λ x4 . x1,
x2,
x3.
The subproof is completed by applying H0.