fact: Definition qzt_getr r qt := if qt isn't QztNode qt5 qt6 qt7 qt8 then QztNil else match r with | Pr55 => qt5 | Pr56 => qt6 | Pr66 => qt6 | Pr57 => qt7 | Pr67 => qt7 | Pr77 => qt7 | Pr58 => qt8 | Pr68 => qt8 | Pr78 => qt8 | Pr88 => qt8 | _ => QztNil end.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry part quiz quiztree)