proposition: Lemma lift_permK : forall n i j s, cancel (@lift_perm_fun n i j s) (lift_perm_fun j i s^-1%g).
proof: Proof. move=> n i j s k; rewrite /lift_perm_fun. by case: (unliftP i k) => [j'|] ->; rewrite (liftK, unlift_none) ?permK. Qed.
imports: ssreflect ssrbool ssrfun eqtype ssrnat seq choice fintype finfun bigops ssralg groups perm zmodp morphisms Ring RingClass bigopsClass Setoid Morphisms