proposition: Lemma matchpg_flip et : matchpg Bstack0 (permt Eperm132 et) =1 matchpg Bstack0 et.
proof: Proof. rewrite -[Bstack0]/(stack_of_bitseq [::]) -{1}[[::]]/(map negb [::]). move; elim: et [::] => [|e et IHet] lb [|s w] //. by case: e (IHet (cbit0 e :: lb) w); case: s => //=; case: lb => [|[]] //=. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype) fourcolor(color)