Apply H0 with
False.
Let x0 of type ι → ι → ι → ι → ι → ι be given.
Apply H1 with
False.
Let x1 of type ι → ι → ι → ι → ι → ι be given.
Apply H2 with
False.
Let x2 of type ι → ι → ι → ι → ι → ι be given.
Apply H3 with
False.
Let x3 of type ι → ι → ι → ι → ι → ι → ι → ι → ι be given.