fact: Definition cube_tag_code o := match o with | CTn => 0 | CTen => 1 | CTf => 2 | CTnf => 3 | CTe => 4 | CTfe => 5 end.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry color coloring)