fact: Definition prange_hi k := match k with | 5 => Pr69 | 6 => Pr79 | 7 => Pr89 | 8 => Pr99 | _ => Pr59 end.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap color geometry)