Let x0 of type ι be given.
Let x1 of type ι be given.
Let x2 of type ι → ο be given.
Let x3 of type ι be given.
Apply H0 with
λ x4 x5 . x3 = ap x5 2.
Let x4 of type ι → ι → ο be given.
The subproof is completed by applying tuple_3_2_eq with
x1,
Sep x1 x2,
x3,
λ x5 x6 . x4 x6 x5.