fact: Hypothesis split_decr: forall l1 l2 a b, l1 = a::b::l2 -> length (fst(split l1)) < length l1 /\ length (snd(split l1)) < length l1.
imports: Coq(List Wf_nat Recdef Compare_dec Arith Peano_dec Lia RelationClasses Sorting.Sorted Sorting.Permutation) hydras(DecPreOrder DecPreOrder_Instances Sort_spec)