proposition: Lemma expilon_prop x: \0o <o x ->(odegree x = x <-> epsilonp x).
proof: Proof. move => xp; split; last by move => [ox {1} <-]; rewrite (odegree_opow ox). move:(the_cnf_split xp) => [ bp bf /proj31_1 oc] eq1 dxx. move:(proj2 (ord_eps_p2 (OS_degree (proj32_1 xp)) bp oc)). by rewrite - eq1 => h; move: (proj33 (h (esym dxx))). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)