proposition: Theorem wlshift_gt : forall sz n (w : word sz), (n > sz)%nat -> wlshift w n = wzero sz.
proof: Proof. intros sz n w H. generalize dependent w. remember (n - sz) as e. assert (n = sz + e) by lia; subst n. intros w. unfold wlshift. rewrite <- combine_wzero. erewrite combine_assoc, eq_rect_word_match. eq_rect_simpl. rewrite eq_rect_combine. apply split1_combine. Unshelve. lia. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Morphisms_Prop Coq.Classes.Equivalence Coq.Arith.PeanoNat Coq.ZArith.BinInt  Coq.Arith.Arith Coq.NArith.NArith Coq.Bool.Bool Coq.ZArith.ZArith Coq.Logic.Eqdep_dec Coq.Logic.EqdepFacts Coq.Program.Tactics Coq.Program.Equality Coq.setoid_ring.Ring Coq.setoid_ring.Ring_polynom bbv.Nomega bbv.ZLib bbv.NatLib bbv.NLib bbv.N_Z_nat_conversions bbv.DepEq bbv.DepEqNat bbv.ReservedNotations Coq.micromega.Lia