fact: Definition gtree_cons_pairs t pt0 pt1 pt2 pt3 := let: GtreePair t'0 t''0 := pt0 in let: GtreePair t'1 t''1 := pt1 in let: GtreePair t'2 t''2 := pt2 in let: GtreePair t'3 t''3 := pt3 in let mkpair0 t' t'' := if gtree_empty4 t' then GtreePair t'0 t else if gtree_empty4 t'' then GtreePair t t''0 else GtreePair t' t'' in mkpair0 (GtreeNode t'0 t'1 t'2 t'3) (GtreeNode t''0 t''1 t''2 t''3).
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq) fourcolor(color chromogram)