proposition: Fact redge_subproof (u : rdart) : edge (sval u) \notin diskE.
proof: Proof. by rewrite -(fclosed1 diskE_edge) (valP u). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap jordan color geometry patch)