proposition: Lemma rev_cycle p : cycle e (rev p) = cycle (fun z => e^~ z) p.
proof: Proof. case: p => //= x p; rewrite -rev_path last_rcons belast_rcons rev_cons. by rewrite -[in LHS]cats1 cycle_catC. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq)