fact: Definition ktc_step closure kr := let: (ctu, gtp) := kr in if ctree_empty ctu then kr else let: GtreePair gtr gtu := gtp in if gtree_empty gtr then kr else if gtree_empty gtu then (CtreeEmpty, empty_gtree_pair) else let: CtreePair ctu' ctr := ctree_restrict h ctu (CtrCons Bstack0 gtr CtrNil) in closure ctu' (ctree_rotlr ctr) gtu.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry color chromogram coloring cfmap) fourcolor(cfcolor dyck ctree initctree gtree initgtree) fourcolor(gtreerestrict ctreerestrict)