fact: Definition Kempe_tree (cp : cprog) : ctree := if cprsize cp is h.+2 then let ctu := ctree_init_tree h.+1 in let gtu := gtree_init_tree h.+1 in let ctr := cpcolor cp in fst (Kempe_tree_closure h h.+2 ctu ctr gtu) else CtreeEmpty.
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)