fact: Definition distinct_pbleaves (t : pbtree) : Prop := forall t0 t1 t2 : pbtree, inpb (pbnode t1 t2) t -> inpb t0 t1 -> inpb t0 t2 -> False.
imports: Coq(List Compare_dec Sorting.Permutation) Huffman(AuxLib Code Build ISort UniqueKey)