diff options
Diffstat (limited to 'theories/Reals/RIneq.v')
| -rw-r--r-- | theories/Reals/RIneq.v | 215 |
1 files changed, 120 insertions, 95 deletions
diff --git a/theories/Reals/RIneq.v b/theories/Reals/RIneq.v index 379fee6f..59a10496 100644 --- a/theories/Reals/RIneq.v +++ b/theories/Reals/RIneq.v @@ -1,10 +1,12 @@ -(* -*- coding: utf-8 -*- *) (************************************************************************) -(* v * The Coq Proof Assistant / The Coq Development Team *) -(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2016 *) +(* * The Coq Proof Assistant / The Coq Development Team *) +(* v * INRIA, CNRS and contributors - Copyright 1999-2018 *) +(* <O___,, * (see CREDITS file for the list of authors) *) (* \VV/ **************************************************************) -(* // * This file is distributed under the terms of the *) -(* * GNU Lesser General Public License Version 2.1 *) +(* // * This file is distributed under the terms of the *) +(* * GNU Lesser General Public License Version 2.1 *) +(* * (see LICENSE file for the text of the license) *) +(************************************************************************) (************************************************************************) (*********************************************************) @@ -1611,6 +1613,9 @@ Proof. Qed. Hint Resolve mult_INR: real. +Lemma pow_INR (m n: nat) : INR (m ^ n) = pow (INR m) n. +Proof. now induction n as [|n IHn];[ | simpl; rewrite mult_INR, IHn]. Qed. + (*********) Lemma lt_0_INR : forall n:nat, (0 < n)%nat -> 0 < INR n. Proof. @@ -1629,7 +1634,7 @@ Hint Resolve lt_INR: real. Lemma lt_1_INR : forall n:nat, (1 < n)%nat -> 1 < INR n. Proof. - intros; replace 1 with (INR 1); auto with real. + apply lt_INR. Qed. Hint Resolve lt_1_INR: real. @@ -1653,17 +1658,16 @@ Hint Resolve pos_INR: real. Lemma INR_lt : forall n m:nat, INR n < INR m -> (n < m)%nat. Proof. - double induction n m; intros. - simpl; exfalso; apply (Rlt_irrefl 0); auto. - auto with arith. - generalize (pos_INR (S n0)); intro; cut (INR 0 = 0); - [ intro H2; rewrite H2 in H0; idtac | simpl; trivial ]. - generalize (Rle_lt_trans 0 (INR (S n0)) 0 H1 H0); intro; exfalso; - apply (Rlt_irrefl 0); auto. - do 2 rewrite S_INR in H1; cut (INR n1 < INR n0). - intro H2; generalize (H0 n0 H2); intro; auto with arith. - apply (Rplus_lt_reg_l 1 (INR n1) (INR n0)). - rewrite Rplus_comm; rewrite (Rplus_comm 1 (INR n0)); trivial. + intros n m. revert n. + induction m ; intros n H. + - elim (Rlt_irrefl 0). + apply Rle_lt_trans with (2 := H). + apply pos_INR. + - destruct n as [|n]. + apply Nat.lt_0_succ. + apply lt_n_S, IHm. + rewrite 2!S_INR in H. + apply Rplus_lt_reg_r with (1 := H). Qed. Hint Resolve INR_lt: real. @@ -1707,14 +1711,10 @@ Hint Resolve not_INR: real. Lemma INR_eq : forall n m:nat, INR n = INR m -> n = m. Proof. - intros; case (le_or_lt n m); intros H1. - case (le_lt_or_eq _ _ H1); intros H2; auto. - cut (n <> m). - intro H3; generalize (not_INR n m H3); intro H4; exfalso; auto. - omega. - symmetry ; cut (m <> n). - intro H3; generalize (not_INR m n H3); intro H4; exfalso; auto. - omega. + intros n m HR. + destruct (dec_eq_nat n m) as [H|H]. + exact H. + now apply not_INR in H. Qed. Hint Resolve INR_eq: real. @@ -1728,7 +1728,8 @@ Hint Resolve INR_le: real. Lemma not_1_INR : forall n:nat, n <> 1%nat -> INR n <> 1. Proof. - replace 1 with (INR 1); auto with real. + intros n. + apply not_INR. Qed. Hint Resolve not_1_INR: real. @@ -1743,24 +1744,40 @@ Proof. intros z; idtac; apply Z_of_nat_complete; assumption. Qed. +Lemma INR_IPR : forall p, INR (Pos.to_nat p) = IPR p. +Proof. + assert (H: forall p, 2 * INR (Pos.to_nat p) = IPR_2 p). + induction p as [p|p|] ; simpl IPR_2. + rewrite Pos2Nat.inj_xI, S_INR, mult_INR, <- IHp. + now rewrite (Rplus_comm (2 * _)). + now rewrite Pos2Nat.inj_xO, mult_INR, <- IHp. + apply Rmult_1_r. + intros [p|p|] ; unfold IPR. + rewrite Pos2Nat.inj_xI, S_INR, mult_INR, <- H. + apply Rplus_comm. + now rewrite Pos2Nat.inj_xO, mult_INR, <- H. + easy. +Qed. + (**********) Lemma INR_IZR_INZ : forall n:nat, INR n = IZR (Z.of_nat n). Proof. - simple induction n; auto with real. - intros; simpl; rewrite SuccNat2Pos.id_succ; - auto with real. + intros [|n]. + easy. + simpl Z.of_nat. unfold IZR. + now rewrite <- INR_IPR, SuccNat2Pos.id_succ. Qed. Lemma plus_IZR_NEG_POS : forall p q:positive, IZR (Zpos p + Zneg q) = IZR (Zpos p) + IZR (Zneg q). Proof. intros p q; simpl. rewrite Z.pos_sub_spec. - case Pos.compare_spec; intros H; simpl. + case Pos.compare_spec; intros H; unfold IZR. subst. ring. - rewrite Pos2Nat.inj_sub by trivial. + rewrite <- 3!INR_IPR, Pos2Nat.inj_sub by trivial. rewrite minus_INR by (now apply lt_le_weak, Pos2Nat.inj_lt). ring. - rewrite Pos2Nat.inj_sub by trivial. + rewrite <- 3!INR_IPR, Pos2Nat.inj_sub by trivial. rewrite minus_INR by (now apply lt_le_weak, Pos2Nat.inj_lt). ring. Qed. @@ -1769,26 +1786,18 @@ Qed. Lemma plus_IZR : forall n m:Z, IZR (n + m) = IZR n + IZR m. Proof. intro z; destruct z; intro t; destruct t; intros; auto with real. - simpl; intros; rewrite Pos2Nat.inj_add; auto with real. + simpl. unfold IZR. rewrite <- 3!INR_IPR, Pos2Nat.inj_add. apply plus_INR. apply plus_IZR_NEG_POS. rewrite Z.add_comm; rewrite Rplus_comm; apply plus_IZR_NEG_POS. - simpl; intros; rewrite Pos2Nat.inj_add; rewrite plus_INR; - auto with real. + simpl. unfold IZR. rewrite <- 3!INR_IPR, Pos2Nat.inj_add, plus_INR. + apply Ropp_plus_distr. Qed. (**********) Lemma mult_IZR : forall n m:Z, IZR (n * m) = IZR n * IZR m. Proof. - intros z t; case z; case t; simpl; auto with real. - intros t1 z1; rewrite Pos2Nat.inj_mul; auto with real. - intros t1 z1; rewrite Pos2Nat.inj_mul; auto with real. - rewrite Rmult_comm. - rewrite Ropp_mult_distr_l_reverse; auto with real. - apply Ropp_eq_compat; rewrite mult_comm; auto with real. - intros t1 z1; rewrite Pos2Nat.inj_mul; auto with real. - rewrite Ropp_mult_distr_l_reverse; auto with real. - intros t1 z1; rewrite Pos2Nat.inj_mul; auto with real. - rewrite Rmult_opp_opp; auto with real. + intros z t; case z; case t; simpl; auto with real; + unfold IZR; intros m n; rewrite <- 3!INR_IPR, Pos2Nat.inj_mul, mult_INR; ring. Qed. Lemma pow_IZR : forall z n, pow (IZR z) n = IZR (Z.pow z (Z.of_nat n)). @@ -1804,13 +1813,13 @@ Qed. (**********) Lemma succ_IZR : forall n:Z, IZR (Z.succ n) = IZR n + 1. Proof. - intro; change 1 with (IZR 1); unfold Z.succ; apply plus_IZR. + intro; unfold Z.succ; apply plus_IZR. Qed. (**********) Lemma opp_IZR : forall n:Z, IZR (- n) = - IZR n. Proof. - intro z; case z; simpl; auto with real. + intros [|z|z]; unfold IZR; simpl; auto with real. Qed. Definition Ropp_Ropp_IZR := opp_IZR. @@ -1833,10 +1842,12 @@ Qed. Lemma lt_0_IZR : forall n:Z, 0 < IZR n -> (0 < n)%Z. Proof. intro z; case z; simpl; intros. - absurd (0 < 0); auto with real. - unfold Z.lt; simpl; trivial. - case Rlt_not_le with (1 := H). - replace 0 with (-0); auto with real. + elim (Rlt_irrefl _ H). + easy. + elim (Rlt_not_le _ _ H). + unfold IZR. + rewrite <- INR_IPR. + auto with real. Qed. (**********) @@ -1852,9 +1863,12 @@ Qed. Lemma eq_IZR_R0 : forall n:Z, IZR n = 0 -> n = 0%Z. Proof. intro z; destruct z; simpl; intros; auto with zarith. - case (Rlt_not_eq 0 (INR (Pos.to_nat p))); auto with real. - case (Rlt_not_eq (- INR (Pos.to_nat p)) 0); auto with real. - apply Ropp_lt_gt_0_contravar. unfold Rgt; apply pos_INR_nat_of_P. + elim Rgt_not_eq with (2 := H). + unfold IZR. rewrite <- INR_IPR. + apply lt_0_INR, Pos2Nat.is_pos. + elim Rlt_not_eq with (2 := H). + unfold IZR. rewrite <- INR_IPR. + apply Ropp_lt_gt_0_contravar, lt_0_INR, Pos2Nat.is_pos. Qed. (**********) @@ -1892,8 +1906,8 @@ Qed. (**********) Lemma le_IZR_R1 : forall n:Z, IZR n <= 1 -> (n <= 1)%Z. Proof. - pattern 1 at 1; replace 1 with (IZR 1); intros; auto. - apply le_IZR; trivial. + intros n. + apply le_IZR. Qed. (**********) @@ -1917,12 +1931,23 @@ Proof. omega. Qed. +Lemma IZR_neq : forall z1 z2:Z, z1 <> z2 -> IZR z1 <> IZR z2. +Proof. +intros; red; intro; elim H; apply eq_IZR; assumption. +Qed. + +Hint Extern 0 (IZR _ <= IZR _) => apply IZR_le, Zle_bool_imp_le, eq_refl : real. +Hint Extern 0 (IZR _ >= IZR _) => apply Rle_ge, IZR_le, Zle_bool_imp_le, eq_refl : real. +Hint Extern 0 (IZR _ < IZR _) => apply IZR_lt, eq_refl : real. +Hint Extern 0 (IZR _ > IZR _) => apply IZR_lt, eq_refl : real. +Hint Extern 0 (IZR _ <> IZR _) => apply IZR_neq, Zeq_bool_neq, eq_refl : real. + Lemma one_IZR_lt1 : forall n:Z, -1 < IZR n < 1 -> n = 0%Z. Proof. intros z [H1 H2]. apply Z.le_antisymm. apply Z.lt_succ_r; apply lt_IZR; trivial. - replace 0%Z with (Z.succ (-1)); trivial. + change 0%Z with (Z.succ (-1)). apply Z.le_succ_l; apply lt_IZR; trivial. Qed. @@ -1999,10 +2024,34 @@ Lemma double_var : forall r1, r1 = r1 / 2 + r1 / 2. Proof. intro; rewrite <- double; unfold Rdiv; rewrite <- Rmult_assoc; symmetry ; apply Rinv_r_simpl_m. - replace 2 with (INR 2); - [ apply not_0_INR; discriminate | unfold INR; ring ]. + now apply not_0_IZR. +Qed. + +Lemma R_rm : ring_morph + 0%R 1%R Rplus Rmult Rminus Ropp eq + 0%Z 1%Z Zplus Zmult Zminus Z.opp Zeq_bool IZR. +Proof. +constructor ; try easy. +exact plus_IZR. +exact minus_IZR. +exact mult_IZR. +exact opp_IZR. +intros x y H. +apply f_equal. +now apply Zeq_bool_eq. +Qed. + +Lemma Zeq_bool_IZR x y : + IZR x = IZR y -> Zeq_bool x y = true. +Proof. +intros H. +apply Zeq_is_eq_bool. +now apply eq_IZR. Qed. +Add Field RField : Rfield + (completeness Zeq_bool_IZR, morphism R_rm, constants [IZR_tac], power_tac R_power_theory [Rpow_tac]). + (*********************************************************) (** ** Other rules about < and <= *) (*********************************************************) @@ -2017,42 +2066,18 @@ Qed. Lemma le_epsilon : forall r1 r2, (forall eps:R, 0 < eps -> r1 <= r2 + eps) -> r1 <= r2. Proof. - intros x y; intros; elim (Rtotal_order x y); intro. - left; assumption. - elim H0; intro. - right; assumption. - clear H0; generalize (Rgt_minus x y H1); intro H2; change (0 < x - y) in H2. - cut (0 < 2). - intro. - generalize (Rmult_lt_0_compat (x - y) (/ 2) H2 (Rinv_0_lt_compat 2 H0)); - intro H3; generalize (H ((x - y) * / 2) H3); - replace (y + (x - y) * / 2) with ((y + x) * / 2). - intro H4; - generalize (Rmult_le_compat_l 2 x ((y + x) * / 2) (Rlt_le 0 2 H0) H4); - rewrite <- (Rmult_comm ((y + x) * / 2)); rewrite Rmult_assoc; - rewrite <- Rinv_l_sym. - rewrite Rmult_1_r; replace (2 * x) with (x + x). - rewrite (Rplus_comm y); intro H5; apply Rplus_le_reg_l with x; assumption. - ring. - replace 2 with (INR 2); [ apply not_0_INR; discriminate | reflexivity ]. - pattern y at 2; replace y with (y / 2 + y / 2). - unfold Rminus, Rdiv. - repeat rewrite Rmult_plus_distr_r. - ring. - cut (forall z:R, 2 * z = z + z). - intro. - rewrite <- (H4 (y / 2)). - unfold Rdiv. - rewrite <- Rmult_assoc; apply Rinv_r_simpl_m. - replace 2 with (INR 2). - apply not_0_INR. - discriminate. - unfold INR; reflexivity. - intro; ring. - cut (0%nat <> 2%nat); - [ intro H0; generalize (lt_0_INR 2 (neq_O_lt 2 H0)); unfold INR; - intro; assumption - | discriminate ]. + intros x y H. + destruct (Rle_or_lt x y) as [H1|H1]. + exact H1. + apply Rplus_le_reg_r with x. + replace (y + x) with (2 * (y + (x - y) * / 2)) by field. + replace (x + x) with (2 * x) by ring. + apply Rmult_le_compat_l. + now apply (IZR_le 0 2). + apply H. + apply Rmult_lt_0_compat. + now apply Rgt_minus. + apply Rinv_0_lt_compat, Rlt_0_2. Qed. (**********) |