Proofgold Proof

pf
Let x0 of type ι be given. Assume H0: SNo x0. Apply minus_SNo_minus_CSNo with x0, λ x1 x2 . SNo x1 leaving 2 subgoals. The subproof is completed by applying H0. Apply SNo_minus_SNo with x0. The subproof is completed by applying H0. ■