fact: Definition ecpN_face x := match x with | IcpX => Icp x0 | IcpXe => if long_cpring x0 then Icp (face (edge (face (edge x0)))) else IcpX G | Icp y => if y == edge (face (edge x0)) then IcpXe G else if y == edge (node x0) then IcpX G else Icp (face y) end.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry color)