proposition: Lemma Spsi_p6 a b: a <o Gamma_0 -> b <o Gamma_0 -> a <o Spsi a b.
proof: Proof. move => pa pb. have oa:= proj31_1 pa. have ob:= proj31_1 pb. have oc:= (OS_Spsi oa ob). move: (Gamma0_s_psi pa pb) => h. apply/(Spsi_p5 oa ob) => /(strong_criticalP oc) h1. by case: (oleNgt(proj2 Gamma0_p _ oc h1)). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)