diff options
Diffstat (limited to 'theories/Numbers/NatInt/NZAddOrder.v')
| -rw-r--r-- | theories/Numbers/NatInt/NZAddOrder.v | 35 |
1 files changed, 25 insertions, 10 deletions
diff --git a/theories/Numbers/NatInt/NZAddOrder.v b/theories/Numbers/NatInt/NZAddOrder.v index ed56cd8f..ee03e5f9 100644 --- a/theories/Numbers/NatInt/NZAddOrder.v +++ b/theories/Numbers/NatInt/NZAddOrder.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 *) @@ -8,12 +8,10 @@ (* Evgeny Makarov, INRIA, 2007 *) (************************************************************************) -(*i $Id: NZAddOrder.v 14641 2011-11-06 11:59:10Z herbelin $ i*) - Require Import NZAxioms NZBase NZMul NZOrder. -Module Type NZAddOrderPropSig (Import NZ : NZOrdAxiomsSig'). -Include NZBasePropSig NZ <+ NZMulPropSig NZ <+ NZOrderPropSig NZ. +Module Type NZAddOrderProp (Import NZ : NZOrdAxiomsSig'). +Include NZBaseProp NZ <+ NZMulProp NZ <+ NZOrderProp NZ. Theorem add_lt_mono_l : forall n m p, n < m <-> p + n < p + m. Proof. @@ -30,7 +28,7 @@ Theorem add_lt_mono : forall n m p q, n < m -> p < q -> n + p < m + q. Proof. intros n m p q H1 H2. apply lt_trans with (m + p); -[now apply -> add_lt_mono_r | now apply -> add_lt_mono_l]. +[now apply add_lt_mono_r | now apply add_lt_mono_l]. Qed. Theorem add_le_mono_l : forall n m p, n <= m <-> p + n <= p + m. @@ -48,21 +46,21 @@ Theorem add_le_mono : forall n m p q, n <= m -> p <= q -> n + p <= m + q. Proof. intros n m p q H1 H2. apply le_trans with (m + p); -[now apply -> add_le_mono_r | now apply -> add_le_mono_l]. +[now apply add_le_mono_r | now apply add_le_mono_l]. Qed. Theorem add_lt_le_mono : forall n m p q, n < m -> p <= q -> n + p < m + q. Proof. intros n m p q H1 H2. apply lt_le_trans with (m + p); -[now apply -> add_lt_mono_r | now apply -> add_le_mono_l]. +[now apply add_lt_mono_r | now apply add_le_mono_l]. Qed. Theorem add_le_lt_mono : forall n m p q, n <= m -> p < q -> n + p < m + q. Proof. intros n m p q H1 H2. apply le_lt_trans with (m + p); -[now apply -> add_le_mono_r | now apply -> add_lt_mono_l]. +[now apply add_le_mono_r | now apply add_lt_mono_l]. Qed. Theorem add_pos_pos : forall n m, 0 < n -> 0 < m -> 0 < n + m. @@ -149,5 +147,22 @@ Proof. intros n m H; apply add_le_cases; now nzsimpl. Qed. -End NZAddOrderPropSig. +(** Substraction *) + +(** We can prove the existence of a subtraction of any number by + a smaller one *) + +Lemma le_exists_sub : forall n m, n<=m -> exists p, m == p+n /\ 0<=p. +Proof. + intros n m H. apply le_ind with (4:=H). solve_proper. + exists 0; nzsimpl; split; order. + clear m H. intros m H (p & EQ & LE). exists (S p). + split. nzsimpl. now f_equiv. now apply le_le_succ_r. +Qed. + +(** For the moment, it doesn't seem possible to relate + this existing subtraction with [sub]. +*) + +End NZAddOrderProp. |