proposition: Lemma Spsi_p2 a b: ordinalp a -> ordinalp b -> b <o Spsi a b.
proof: Proof. move => oa ob. move: (Spsi_p1' oa ob). rewrite /Spsi; set c := Yo _ _ _ => e1. suff bc : b <=o c by apply:(ole_ltT bc e1). rewrite /c; Ytac h; [ apply: (proj1(oltS ob)) | fprops]. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)