proposition: Lemma insetW r : subpred (inset r) r.
proof: Proof. by move=> p /insetP/(_ p (gtouch_refl p)). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(div choice order ssralg ssrnum ssrint intdiv) fourcolor(hypermap)