fact: Record matte := Matte { mdisk :> seq gpoint; mring : seq gpoint; matte_ne : ~~ nilp mdisk; mring_cycle : cycle mrlink mring; mring_simple : uniq (map end0g mring); in_mring : mring =i gborder mdisk }.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(path order ssralg ssrnum ssrint div intdiv) fourcolor(grid)