fact: Definition zcard l := \prod_(i <- l) i * \prod_(i < (sumn l).+1) (count_mem (i : nat) l)`!.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq fintype) mathcomp(tuple path bigop finset div) mathcomp(fingroup perm action gproduct morphism) tools partition permcomp cycles cycletype