fact: Definition ctree_init_tree h := if iter h.-1 ctree_merge_table (ctree_leaf_table h) is [:: CtreePair t0 t1, CtreePair t2 t3 & _] then ctree_cons (ctree_prune_1 t1) (ctree_prune_2 t2) (ctree_prune_3 t3) else CtreeEmpty.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq) fourcolor(color ctree dyck)