fact: Definition ptree_meld (p1 p2 : ptree) : ptree := match p1, p2 with | PTsome v1 l1, PTsome v2 l2 => if le v1 v2 then PTsome v1 (p2 :: l1) else PTsome v2 (p1 :: l2) end.
imports: Coq(List Arith ZArith Psatz) mathcomp.ssreflect(ssrfun ssrbool fintype)