Proofgold Proof

pf
Apply nat_ind with λ x0 . ordinal x0 leaving 2 subgoals. The subproof is completed by applying ordinal_Empty. Let x0 of type ι be given. Assume H0: nat_p x0. Assume H1: ordinal x0. Apply ordinal_ordsucc with x0. The subproof is completed by applying H1. ■