Proofgold Proof

pf
Let x0 of type ι be given. Let x1 of type ι be given. Assume H0: SNo x0. Assume H1: SNo x1. Assume H2: SNo (minus_SNo x1). Apply minus_add_SNo_distr with x0, x1 leaving 2 subgoals. The subproof is completed by applying H0. The subproof is completed by applying H1. ■