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(* modify it under the terms of the GNU Lesser General Public License *)
(* as published by the Free Software Foundation; either version 2.1   *)
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(* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the      *)
(* GNU General Public License for more details.                       *)
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(* 02110-1301 USA                                                     *)
Require Export MiscRsa.
(******************************************************************************)
Inductive divides : nat -> nat -> Prop :=
dividesDef : forall a b q : nat, b = q * a -> divides a b.
intros a; apply dividesDef with (q := 1); auto with arith.
Qed.
intros x y; case x; case y; auto.
left; apply dividesDef with (q := 0); auto.
intros n; right; red in |- *; intros H'; inversion_clear H'.
rewrite (mult_comm q 0) in H; discriminate.
intros n; left; apply dividesDef with (q := 0); auto.
intros x' y'; case (divides_dec' (S x') (S y')); auto.
intros H'; left; apply div_divides; auto.
intros H'; right; red in |- *; intros H'0; case H'; auto.
inversion H'0.
exists q; auto.
apply is_div_def; auto with arith.
rewrite H; auto with arith.
Qed.

Theorem divides_le : forall a b : nat, b <> 0 -> divides a b -> a <= b.