Library Combi.SSRcomplements.permcomp: Complement on permutations

A few lemmas on permutation

Require Import mathcomp.ssreflect.ssreflect.
From mathcomp Require Import ssrfun ssrbool eqtype ssrnat seq choice fintype div.
From mathcomp Require Import finset fingroup perm morphism action.

Set Implicit Arguments.

Import GroupScope.

Orbit and cycles

Section PermComp.

Variable T : finType.
Implicit Type (s : {perm T}) (X : {set T}) (P : {set {set T}}).

Lemma permKP s : reflect (involutive s) (s^-1 == s).

End PermComp.

Section SetAct.

Variables (aT : finGroupType) (D : {set aT}) (rT : finType) (to : action D rT).

TODO: complete setactU, setactI, setactD ... and submit to mathcomp
Lemma setact0 a : to^* set0 a = set0.
Lemma setact1 x a : to^* [set x] a = [set to x a].
Lemma setactI S T a : to^* (S :&: T) a = to^* S a :&: to^* T a.
Lemma setactU S T a : to^* (S :|: T) a = to^* S a :|: to^* T a.
Lemma setactU1 x T a : to^* (x |: T) a = to x a |: to^* T a.

Lemma setactC S a : to^* (~: S) a = ~: to^* S a.

End SetAct.