Local Hint Resolve le_0_x : a.
(* <KEEP TOGETHER - modred_equations *)
Let s := ursh u_in_Z_ p_in_Z_w.
Let s' := multp2 s p_in_Z_w.
Let h := multp2 v_in_Z_ t_in_Z_w.
Let h' := plusw h s.
Let q := uhwm h' M'_in_Z_.
Let q' := plusw q h'.
Let y := multw q' M_in_Z_.
Let d := minusw s' y.
Let r := minusw u_in_Z_ y.
Let r' := ltw d M_in_Z_ r (minusw r M_in_Z_).
Let r'' := ltw r' M_in_Z_ r' (minusw r' M_in_Z_).
Let r''' := ltw r'' M_in_Z_ r'' (minusw r'' M_in_Z_).
(* KEEP TOGETHER> *)
Definition ModRed := _Z r'''. (* keeps _Z out of ModRed_eq *)

Lemma l_eq : u = x mod 2 ^ w.
unfold x. rewrite Zmod_km_plus. symmetry. apply modred. auto with a. auto with a. auto with a. Qed.