fact: Definition gtouch p := let: Gpoint x y := p in Grect (x - 1) (x + 2) (y - 1) (y + 2).
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(div choice order ssralg ssrnum ssrint intdiv) fourcolor(hypermap)