proposition: Lemma check_unfitP (x : G) p : fitp x p -> forall ru, dbound1 ru x = 0 -> check_unfit p ru = false.
proof: Proof. move=> fit_xp; elim=> //= r ru IHru; case fit_xr: (fitp x r) => // /IHru->. by move: fit_xr; rewrite (fitp_cmp fit_xp); case: (cmp_part p r). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) mathcomp(bigop order ssralg ssrnum ssrint) fourcolor(hypermap geometry quiztree part discharge)