Proofgold Proof

pf
Let x0 of type ι be given. Assume H0: x0 ∈ Sing 0. Apply SingE with 0, x0, λ x1 x2 . x0 ∈ ordsucc x1 leaving 2 subgoals. The subproof is completed by applying H0. The subproof is completed by applying ordsuccI2 with x0. ■