Let x0 of type ι be given.
Apply unknownprop_187aa2a404b6b5b0ab970bae8b3b9119c8f3de729d81252d0b31199ef88fbb6a with
λ x1 x2 : ι → ο . x2 x0.
Apply unknownprop_389e2fb1855352fcc964ea44fe6723d7a1c2d512f04685300e3e97621725b977 with
atleast3 x0,
not (atleast4 x0) leaving 2 subgoals.
The subproof is completed by applying H0.
The subproof is completed by applying H1.