Let x0 of type ι be given.
Let x1 of type ι be given.
Let x2 of type ι be given.
Apply H2 with
False.
Apply setminusE with
K_field_0 x0 x0,
Sing (K_field_3 x0 x0),
x2,
False leaving 2 subgoals.
The subproof is completed by applying H4.
Apply H1.
The subproof is completed by applying H5.