Let x0 of type ι be given.
Let x1 of type ι → ι be given.
Let x2 of type ι → ι → ο be given.
Let x3 of type ι be given.
Apply unknownprop_6ec2471d5ee34f4f3ae811a663f1751db4e03541c09372cd0f7577a153ca6e0a with
1bcc7.. x0 x1 x2 x3,
x0,
x1,
x2,
x3.
Let x4 of type ι → ι → ο be given.
The subproof is completed by applying H0.