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Diffstat (limited to 'coqprime-8.4/Coqprime/ZCAux.v')
| -rw-r--r-- | coqprime-8.4/Coqprime/ZCAux.v | 295 |
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diff --git a/coqprime-8.4/Coqprime/ZCAux.v b/coqprime-8.4/Coqprime/ZCAux.v new file mode 100644 index 000000000..aa47fb655 --- /dev/null +++ b/coqprime-8.4/Coqprime/ZCAux.v @@ -0,0 +1,295 @@ + +(*************************************************************) +(* This file is distributed under the terms of the *) +(* GNU Lesser General Public License Version 2.1 *) +(*************************************************************) +(* Benjamin.Gregoire@inria.fr Laurent.Thery@inria.fr *) +(*************************************************************) + +(********************************************************************** + ZCAux.v + + Auxillary functions & Theorems + **********************************************************************) + +Require Import Coq.setoid_ring.ArithRing. +Require Export Coq.ZArith.ZArith Coq.ZArith.Zpow_facts. +Require Export Coq.ZArith.Znumtheory. +Require Export Coqprime.Tactic. + +Theorem Zdivide_div_prime_le_square: forall x, 1 < x -> ~prime x -> exists p, prime p /\ (p | x) /\ p * p <= x. +intros x Hx; generalize Hx; pattern x; apply Z_lt_induction; auto with zarith. +clear x Hx; intros x Rec H H1. +case (not_prime_divide x); auto. +intros x1 ((H2, H3), H4); case (prime_dec x1); intros H5. +case (Zle_or_lt (x1 * x1) x); intros H6. +exists x1; auto. +case H4; clear H4; intros x2 H4; subst. +assert (Hx2: x2 <= x1). +case (Zle_or_lt x2 x1); auto; intros H8; contradict H6; apply Zle_not_lt. +apply Zmult_le_compat_r; auto with zarith. +case (prime_dec x2); intros H7. +exists x2; repeat (split; auto with zarith). +apply Zmult_le_compat_l; auto with zarith. +apply Zle_trans with 2%Z; try apply prime_ge_2; auto with zarith. +case (Zle_or_lt 0 x2); intros H8. +case Zle_lt_or_eq with (1 := H8); auto with zarith; clear H8; intros H8; subst; auto with zarith. +case (Zle_lt_or_eq 1 x2); auto with zarith; clear H8; intros H8; subst; auto with zarith. +case (Rec x2); try split; auto with zarith. +intros x3 (H9, (H10, H11)). +exists x3; repeat (split; auto with zarith). +contradict H; apply Zle_not_lt; auto with zarith. +apply Zle_trans with (0 * x1); auto with zarith. +case (Rec x1); try split; auto with zarith. +intros x3 (H9, (H10, H11)). +exists x3; repeat (split; auto with zarith). +apply Zdivide_trans with x1; auto with zarith. +Qed. + + +Theorem Zmult_interval: forall p q, 0 < p * q -> 1 < p -> 0 < q < p * q. +intros p q H1 H2; assert (0 < q). +case (Zle_or_lt q 0); auto; intros H3; contradict H1; apply Zle_not_lt. +rewrite <- (Zmult_0_r p). +apply Zmult_le_compat_l; auto with zarith. +split; auto. +pattern q at 1; rewrite <- (Zmult_1_l q). +apply Zmult_lt_compat_r; auto with zarith. +Qed. + +Theorem prime_induction: forall (P: Z -> Prop), P 0 -> P 1 -> (forall p q, prime p -> P q -> P (p * q)) -> forall p, 0 <= p -> P p. +intros P H H1 H2 p Hp. +generalize Hp; pattern p; apply Z_lt_induction; auto; clear p Hp. +intros p Rec Hp. +case Zle_lt_or_eq with (1 := Hp); clear Hp; intros Hp; subst; auto. +case (Zle_lt_or_eq 1 p); auto with zarith; clear Hp; intros Hp; subst; auto. +case (prime_dec p); intros H3. +rewrite <- (Zmult_1_r p); apply H2; auto. + case (Zdivide_div_prime_le_square p); auto. +intros q (Hq1, ((q2, Hq2), Hq3)); subst. +case (Zmult_interval q q2). +rewrite Zmult_comm; apply Zlt_trans with 1; auto with zarith. +apply Zlt_le_trans with 2; auto with zarith; apply prime_ge_2; auto. +intros H4 H5; rewrite Zmult_comm; apply H2; auto. +apply Rec; try split; auto with zarith. +rewrite Zmult_comm; auto. +Qed. + +Theorem div_power_max: forall p q, 1 < p -> 0 < q -> exists n, 0 <= n /\ (p ^n | q) /\ ~(p ^(1 + n) | q). +intros p q H1 H2; generalize H2; pattern q; apply Z_lt_induction; auto with zarith; clear q H2. +intros q Rec H2. +case (Zdivide_dec p q); intros H3. +case (Zdivide_Zdiv_lt_pos p q); auto with zarith; intros H4 H5. +case (Rec (Zdiv q p)); auto with zarith. +intros n (Ha1, (Ha2, Ha3)); exists (n + 1); split; auto with zarith; split. +case Ha2; intros q1 Hq; exists q1. +rewrite Zpower_exp; try rewrite Zpower_1_r; auto with zarith. +rewrite Zmult_assoc; rewrite <- Hq. +rewrite Zmult_comm; apply Zdivide_Zdiv_eq; auto with zarith. +intros (q1, Hu); case Ha3; exists q1. +apply Zmult_reg_r with p; auto with zarith. +rewrite (Zmult_comm (q / p)); rewrite <- Zdivide_Zdiv_eq; auto with zarith. +apply trans_equal with (1 := Hu); repeat rewrite Zpower_exp; try rewrite Zpower_exp_1; auto with zarith. +ring. +exists 0; repeat split; try rewrite Zpower_1_r; try rewrite Zpower_exp_0; auto with zarith. +Qed. + +Theorem prime_div_induction: + forall (P: Z -> Prop) n, + 0 < n -> + (P 1) -> + (forall p i, prime p -> 0 <= i -> (p^i | n) -> P (p^i)) -> + (forall p q, rel_prime p q -> P p -> P q -> P (p * q)) -> + forall m, 0 <= m -> (m | n) -> P m. +intros P n P1 Hn H H1 m Hm. +generalize Hm; pattern m; apply Z_lt_induction; auto; clear m Hm. +intros m Rec Hm H2. +case (prime_dec m); intros Hm1. +rewrite <- Zpower_1_r; apply H; auto with zarith. +rewrite Zpower_1_r; auto. +case Zle_lt_or_eq with (1 := Hm); clear Hm; intros Hm; subst. +2: contradict P1; case H2; intros; subst; auto with zarith. +case (Zle_lt_or_eq 1 m); auto with zarith; clear Hm; intros Hm; subst; auto. +case Zdivide_div_prime_le_square with m; auto. +intros p (Hp1, (Hp2, Hp3)). +case (div_power_max p m); auto with zarith. +generalize (prime_ge_2 p Hp1); auto with zarith. +intros i (Hi, (Hi1, Hi2)). +case Zle_lt_or_eq with (1 := Hi); clear Hi; intros Hi. +assert (Hpi: 0 < p ^ i). +apply Zpower_gt_0; auto with zarith. +apply Zlt_le_trans with 2; try apply prime_ge_2; auto with zarith. +rewrite (Z_div_exact_2 m (p ^ i)); auto with zarith. +apply H1; auto with zarith. +apply rel_prime_sym; apply rel_prime_Zpower_r; auto with zarith. +apply rel_prime_sym. +apply prime_rel_prime; auto. +contradict Hi2. +case Hi1; intros; subst. +rewrite Z_div_mult in Hi2; auto with zarith. +case Hi2; intros q0 Hq0; subst. +exists q0; rewrite Zpower_exp; try rewrite Zpower_1_r; auto with zarith. +apply H; auto with zarith. +apply Zdivide_trans with (1 := Hi1); auto. +apply Rec; auto with zarith. +split; auto with zarith. +apply Z_div_pos; auto with zarith. +apply Z_div_lt; auto with zarith. +apply Zle_ge; apply Zle_trans with p. +apply prime_ge_2; auto. +pattern p at 1; rewrite <- Zpower_1_r; apply Zpower_le_monotone; auto with zarith. +apply Zlt_le_trans with 2; try apply prime_ge_2; auto with zarith. +apply Z_div_pos; auto with zarith. +apply Zdivide_trans with (2 := H2); auto. +exists (p ^ i); apply Z_div_exact_2; auto with zarith. +apply Zdivide_mod; auto with zarith. +apply Zdivide_mod; auto with zarith. +case Hi2; rewrite <- Hi; rewrite Zplus_0_r; rewrite Zpower_1_r; auto. +Qed. + +Theorem prime_div_Zpower_prime: forall n p q, 0 <= n -> prime p -> prime q -> (p | q ^ n) -> p = q. +intros n p q Hp Hq; generalize p q Hq; pattern n; apply natlike_ind; auto; clear n p q Hp Hq. +intros p q Hp Hq; rewrite Zpower_0_r. +intros (r, H); subst. +case (Zmult_interval p r); auto; try rewrite Zmult_comm. +rewrite <- H; auto with zarith. +apply Zlt_le_trans with 2; try apply prime_ge_2; auto with zarith. +rewrite <- H; intros H1 H2; contradict H2; auto with zarith. +intros n1 H Rec p q Hp Hq; try rewrite Zpower_Zsucc; auto with zarith; intros H1. +case prime_mult with (2 := H1); auto. +intros H2; apply prime_div_prime; auto. +Qed. + +Definition Zmodd a b := +match a with +| Z0 => 0 +| Zpos a' => + match b with + | Z0 => 0 + | Zpos _ => Zmod_POS a' b + | Zneg b' => + let r := Zmod_POS a' (Zpos b') in + match r with Z0 => 0 | _ => b + r end + end +| Zneg a' => + match b with + | Z0 => 0 + | Zpos _ => + let r := Zmod_POS a' b in + match r with Z0 => 0 | _ => b - r end + | Zneg b' => - (Zmod_POS a' (Zpos b')) + end +end. + +Theorem Zmodd_correct: forall a b, Zmodd a b = Zmod a b. +intros a b; unfold Zmod; case a; simpl; auto. +intros p; case b; simpl; auto. +intros p1; refine (Zmod_POS_correct _ _); auto. +intros p1; rewrite Zmod_POS_correct; auto. +case (Zdiv_eucl_POS p (Zpos p1)); simpl; intros z1 z2; case z2; auto. +intros p; case b; simpl; auto. +intros p1; rewrite Zmod_POS_correct; auto. +case (Zdiv_eucl_POS p (Zpos p1)); simpl; intros z1 z2; case z2; auto. +intros p1; rewrite Zmod_POS_correct; simpl; auto. +case (Zdiv_eucl_POS p (Zpos p1)); auto. +Qed. + +Theorem prime_divide_prime_eq: + forall p1 p2, prime p1 -> prime p2 -> Zdivide p1 p2 -> p1 = p2. +intros p1 p2 Hp1 Hp2 Hp3. +assert (Ha: 1 < p1). +inversion Hp1; auto. +assert (Ha1: 1 < p2). +inversion Hp2; auto. +case (Zle_lt_or_eq p1 p2); auto with zarith. +apply Zdivide_le; auto with zarith. +intros Hp4. +case (prime_div_prime p1 p2); auto with zarith. +Qed. + +Theorem Zdivide_Zpower: forall n m, 0 < n -> (forall p i, prime p -> 0 < i -> (p^i | n) -> (p^i | m)) -> (n | m). +intros n m Hn; generalize m Hn; pattern n; apply prime_induction; auto with zarith; clear n m Hn. +intros m H1; contradict H1; auto with zarith. +intros p q H Rec m H1 H2. +assert (H3: (p | m)). +rewrite <- (Zpower_1_r p); apply H2; auto with zarith; rewrite Zpower_1_r; apply Zdivide_factor_r. +case (Zmult_interval p q); auto. +apply Zlt_le_trans with 2; auto with zarith; apply prime_ge_2; auto. +case H3; intros k Hk; subst. +intros Hq Hq1. +rewrite (Zmult_comm k); apply Zmult_divide_compat_l. +apply Rec; auto. +intros p1 i Hp1 Hp2 Hp3. +case (Z_eq_dec p p1); intros Hpp1; subst. +case (H2 p1 (Zsucc i)); auto with zarith. +rewrite Zpower_Zsucc; try apply Zmult_divide_compat_l; auto with zarith. +intros q2 Hq2; exists q2. +apply Zmult_reg_r with p1. +contradict H; subst; apply not_prime_0. +rewrite Hq2; rewrite Zpower_Zsucc; try ring; auto with zarith. +apply Gauss with p. +rewrite Zmult_comm; apply H2; auto. +apply Zdivide_trans with (1:= Hp3). +apply Zdivide_factor_l. +apply rel_prime_sym; apply rel_prime_Zpower_r; auto with zarith. +apply prime_rel_prime; auto. +contradict Hpp1; apply prime_divide_prime_eq; auto. +Qed. + +Theorem prime_divide_Zpower_Zdiv: forall m a p i, 0 <= i -> prime p -> (m | a) -> ~(m | (a/p)) -> (p^i | a) -> (p^i | m). +intros m a p i Hi Hp (k, Hk) H (l, Hl); subst. +case (Zle_lt_or_eq 0 i); auto with arith; intros Hi1; subst. +assert (Hp0: 0 < p). +apply Zlt_le_trans with 2; auto with zarith; apply prime_ge_2; auto. +case (Zdivide_dec p k); intros H1. +case H1; intros k' H2; subst. +case H; replace (k' * p * m) with ((k' * m) * p); try ring; rewrite Z_div_mult; auto with zarith. +apply Gauss with k. +exists l; rewrite Hl; ring. +apply rel_prime_sym; apply rel_prime_Zpower_r; auto. +apply rel_prime_sym; apply prime_rel_prime; auto. +rewrite Zpower_0_r; apply Zone_divide. +Qed. + +Theorem Zle_square_mult: forall a b, 0 <= a <= b -> a * a <= b * b. +intros a b (H1, H2); apply Zle_trans with (a * b); auto with zarith. +Qed. + +Theorem Zlt_square_mult_inv: forall a b, 0 <= a -> 0 <= b -> a * a < b * b -> a < b. +intros a b H1 H2 H3; case (Zle_or_lt b a); auto; intros H4; apply Zmult_lt_reg_r with a; + contradict H3; apply Zle_not_lt; apply Zle_square_mult; auto. +Qed. + + +Theorem Zmod_closeby_eq: forall a b n, 0 <= a -> 0 <= b < n -> a - b < n -> a mod n = b -> a = b. +intros a b n H H1 H2 H3. +case (Zle_or_lt 0 (a - b)); intros H4. +case Zle_lt_or_eq with (1 := H4); clear H4; intros H4; auto with zarith. +contradict H2; apply Zle_not_lt; apply Zdivide_le; auto with zarith. +apply Zmod_divide_minus; auto with zarith. +rewrite <- (Zmod_small a n); try split; auto with zarith. +Qed. + + +Theorem Zpow_mod_pos_Zpower_pos_correct: forall a m n, 0 < n -> Zpow_mod_pos a m n = (Zpower_pos a m) mod n. +intros a m; elim m; simpl; auto. +intros p Rec n H1; rewrite xI_succ_xO; rewrite Pplus_one_succ_r; rewrite <- Pplus_diag; auto. +repeat rewrite Zpower_pos_is_exp; auto. +repeat rewrite Rec; auto. +replace (Zpower_pos a 1) with a; auto. +2: unfold Zpower_pos; simpl; auto with zarith. +repeat rewrite (fun x => (Zmult_mod x a)); auto. +rewrite (Zmult_mod (Zpower_pos a p)); auto. +case (Zpower_pos a p mod n); auto. +intros p Rec n H1; rewrite <- Pplus_diag; auto. +repeat rewrite Zpower_pos_is_exp; auto. +repeat rewrite Rec; auto. +rewrite (Zmult_mod (Zpower_pos a p)); auto. +case (Zpower_pos a p mod n); auto. +unfold Zpower_pos; simpl; rewrite Zmult_1_r; auto with zarith. +Qed. + +Theorem Zpow_mod_Zpower_correct: forall a m n, 1 < n -> 0 <= m -> Zpow_mod a m n = (a ^ m) mod n. +intros a m n; case m; simpl; auto. +intros; apply Zpow_mod_pos_Zpower_pos_correct; auto with zarith. +Qed. |