fact: Fixpoint srpath x0 x p : bool := if p is y :: p' then [&& cface (edge x) y, all (predC (cface x)) p' & srpath x0 y p'] else cface (edge x) x0.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap jordan)