Let x0 of type ι be given.
Let x1 of type ι be given.
Apply add_SNo_prop1 with
x0,
x1,
SNoCutP (binunion {add_SNo x2 x1|x2 ∈ SNoL x0} {add_SNo x0 x2|x2 ∈ SNoL x1}) (binunion {add_SNo x2 x1|x2 ∈ SNoR x0} {add_SNo x0 x2|x2 ∈ SNoR x1}) leaving 3 subgoals.
The subproof is completed by applying H0.
The subproof is completed by applying H1.
The subproof is completed by applying H3.