fact: Definition porbit_set s : {set {set T}} := [set x in porbits s | #|x| != 1%N].
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq fintype) mathcomp(tuple path bigop finset div) mathcomp(fingroup perm action ssralg) tools permcomp