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-rw-r--r--theories/Numbers/NatInt/NZMul.v37
1 files changed, 28 insertions, 9 deletions
diff --git a/theories/Numbers/NatInt/NZMul.v b/theories/Numbers/NatInt/NZMul.v
index b1adcea9..2b5a1cf3 100644
--- a/theories/Numbers/NatInt/NZMul.v
+++ b/theories/Numbers/NatInt/NZMul.v
@@ -1,6 +1,6 @@
(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
-(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2011 *)
+(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2010 *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
@@ -8,13 +8,10 @@
(* Evgeny Makarov, INRIA, 2007 *)
(************************************************************************)
-(*i $Id: NZMul.v 14641 2011-11-06 11:59:10Z herbelin $ i*)
-
Require Import NZAxioms NZBase NZAdd.
-Module Type NZMulPropSig
- (Import NZ : NZAxiomsSig')(Import NZBase : NZBasePropSig NZ).
-Include NZAddPropSig NZ NZBase.
+Module Type NZMulProp (Import NZ : NZAxiomsSig')(Import NZBase : NZBaseProp NZ).
+Include NZAddProp NZ NZBase.
Theorem mul_0_r : forall n, n * 0 == 0.
Proof.
@@ -59,12 +56,34 @@ Qed.
Theorem mul_1_l : forall n, 1 * n == n.
Proof.
-intro n. now nzsimpl.
+intro n. now nzsimpl'.
Qed.
Theorem mul_1_r : forall n, n * 1 == n.
Proof.
-intro n. now nzsimpl.
+intro n. now nzsimpl'.
+Qed.
+
+Hint Rewrite mul_1_l mul_1_r : nz.
+
+Theorem mul_shuffle0 : forall n m p, n*m*p == n*p*m.
+Proof.
+intros n m p. now rewrite <- 2 mul_assoc, (mul_comm m).
+Qed.
+
+Theorem mul_shuffle1 : forall n m p q, (n * m) * (p * q) == (n * p) * (m * q).
+Proof.
+intros n m p q. now rewrite 2 mul_assoc, (mul_shuffle0 n).
+Qed.
+
+Theorem mul_shuffle2 : forall n m p q, (n * m) * (p * q) == (n * q) * (m * p).
+Proof.
+intros n m p q. rewrite (mul_comm p). apply mul_shuffle1.
+Qed.
+
+Theorem mul_shuffle3 : forall n m p, n * (m * p) == m * (n * p).
+Proof.
+intros n m p. now rewrite mul_assoc, (mul_comm n), mul_assoc.
Qed.
-End NZMulPropSig.
+End NZMulProp.