fact: Definition switch_edges := [ffun x => if x \in switch_edom then if [pick ant | (edges c ant == x) && (ant \in edom c)] is Some ant then ant else x else x].
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist subgraph_partition tanner