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diff --git a/theories7/Reals/AltSeries.v b/theories7/Reals/AltSeries.v deleted file mode 100644 index af4b558a..00000000 --- a/theories7/Reals/AltSeries.v +++ /dev/null @@ -1,362 +0,0 @@ -(************************************************************************) -(* v * The Coq Proof Assistant / The Coq Development Team *) -(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *) -(* \VV/ **************************************************************) -(* // * This file is distributed under the terms of the *) -(* * GNU Lesser General Public License Version 2.1 *) -(************************************************************************) - -(*i $Id: AltSeries.v,v 1.1.2.1 2004/07/16 19:31:31 herbelin Exp $ i*) - -Require Rbase. -Require Rfunctions. -Require Rseries. -Require SeqProp. -Require PartSum. -Require Max. -V7only [ Import nat_scope. Import Z_scope. Import R_scope. ]. -Open Local Scope R_scope. - -(**********) -Definition tg_alt [Un:nat->R] : nat->R := [i:nat]``(pow (-1) i)*(Un i)``. -Definition positivity_seq [Un:nat->R] : Prop := (n:nat)``0<=(Un n)``. - -Lemma CV_ALT_step0 : (Un:nat->R) (Un_decreasing Un) -> (Un_growing [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). -Intros; Unfold Un_growing; Intro. -Cut (mult (S (S O)) (S n)) = (S (S (mult (2) n))). -Intro; Rewrite H0. -Do 4 Rewrite tech5; Repeat Rewrite Rplus_assoc; Apply Rle_compatibility. -Pattern 1 (tg_alt Un (S (mult (S (S O)) n))); Rewrite <- Rplus_Or. -Apply Rle_compatibility. -Unfold tg_alt; Rewrite <- H0; Rewrite pow_1_odd; Rewrite pow_1_even; Rewrite Rmult_1l. -Apply Rle_anti_compatibility with ``(Un (S (mult (S (S O)) (S n))))``. -Rewrite Rplus_Or; Replace ``(Un (S (mult (S (S O)) (S n))))+((Un (mult (S (S O)) (S n)))+ -1*(Un (S (mult (S (S O)) (S n)))))`` with ``(Un (mult (S (S O)) (S n)))``; [Idtac | Ring]. -Apply H. -Cut (n:nat) (S n)=(plus n (1)); [Intro | Intro; Ring]. -Rewrite (H0 n); Rewrite (H0 (S (mult (2) n))); Rewrite (H0 (mult (2) n)); Ring. -Qed. - -Lemma CV_ALT_step1 : (Un:nat->R) (Un_decreasing Un) -> (Un_decreasing [N:nat](sum_f_R0 (tg_alt Un) (mult (2) N))). -Intros; Unfold Un_decreasing; Intro. -Cut (mult (S (S O)) (S n)) = (S (S (mult (2) n))). -Intro; Rewrite H0; Do 2 Rewrite tech5; Repeat Rewrite Rplus_assoc. -Pattern 2 (sum_f_R0 (tg_alt Un) (mult (S (S O)) n)); Rewrite <- Rplus_Or. -Apply Rle_compatibility. -Unfold tg_alt; Rewrite <- H0; Rewrite pow_1_odd; Rewrite pow_1_even; Rewrite Rmult_1l. -Apply Rle_anti_compatibility with ``(Un (S (mult (S (S O)) n)))``. -Rewrite Rplus_Or; Replace ``(Un (S (mult (S (S O)) n)))+( -1*(Un (S (mult (S (S O)) n)))+(Un (mult (S (S O)) (S n))))`` with ``(Un (mult (S (S O)) (S n)))``; [Idtac | Ring]. -Rewrite H0; Apply H. -Cut (n:nat) (S n)=(plus n (1)); [Intro | Intro; Ring]. -Rewrite (H0 n); Rewrite (H0 (S (mult (2) n))); Rewrite (H0 (mult (2) n)); Ring. -Qed. - -(**********) -Lemma CV_ALT_step2 : (Un:nat->R;N:nat) (Un_decreasing Un) -> (positivity_seq Un) -> (Rle (sum_f_R0 [i:nat](tg_alt Un (S i)) (S (mult (2) N))) R0). -Intros; Induction N. -Simpl; Unfold tg_alt; Simpl; Rewrite Rmult_1r. -Replace ``-1* -1*(Un (S (S O)))`` with (Un (S (S O))); [Idtac | Ring]. -Apply Rle_anti_compatibility with ``(Un (S O))``; Rewrite Rplus_Or. -Replace ``(Un (S O))+ (-1*(Un (S O))+(Un (S (S O))))`` with (Un (S (S O))); [Apply H | Ring]. -Cut (S (mult (2) (S N))) = (S (S (S (mult (2) N)))). -Intro; Rewrite H1; Do 2 Rewrite tech5. -Apply Rle_trans with (sum_f_R0 [i:nat](tg_alt Un (S i)) (S (mult (S (S O)) N))). -Pattern 2 (sum_f_R0 [i:nat](tg_alt Un (S i)) (S (mult (S (S O)) N))); Rewrite <- Rplus_Or. -Rewrite Rplus_assoc; Apply Rle_compatibility. -Unfold tg_alt; Rewrite <- H1. -Rewrite pow_1_odd. -Cut (S (S (mult (2) (S N)))) = (mult (2) (S (S N))). -Intro; Rewrite H2; Rewrite pow_1_even; Rewrite Rmult_1l; Rewrite <- H2. -Apply Rle_anti_compatibility with ``(Un (S (mult (S (S O)) (S N))))``. -Rewrite Rplus_Or; Replace ``(Un (S (mult (S (S O)) (S N))))+( -1*(Un (S (mult (S (S O)) (S N))))+(Un (S (S (mult (S (S O)) (S N))))))`` with ``(Un (S (S (mult (S (S O)) (S N)))))``; [Idtac | Ring]. -Apply H. -Apply INR_eq; Rewrite mult_INR; Repeat Rewrite S_INR; Rewrite mult_INR; Repeat Rewrite S_INR; Ring. -Apply HrecN. -Apply INR_eq; Repeat Rewrite S_INR; Do 2 Rewrite mult_INR; Repeat Rewrite S_INR; Ring. -Qed. - -(* A more general inequality *) -Lemma CV_ALT_step3 : (Un:nat->R;N:nat) (Un_decreasing Un) -> (positivity_seq Un) -> (Rle (sum_f_R0 [i:nat](tg_alt Un (S i)) N) R0). -Intros; Induction N. -Simpl; Unfold tg_alt; Simpl; Rewrite Rmult_1r. -Apply Rle_anti_compatibility with (Un (S O)). -Rewrite Rplus_Or; Replace ``(Un (S O))+ -1*(Un (S O))`` with R0; [Apply H0 | Ring]. -Assert H1 := (even_odd_cor N). -Elim H1; Intros. -Elim H2; Intro. -Rewrite H3; Apply CV_ALT_step2; Assumption. -Rewrite H3; Rewrite tech5. -Apply Rle_trans with (sum_f_R0 [i:nat](tg_alt Un (S i)) (S (mult (S (S O)) x))). -Pattern 2 (sum_f_R0 [i:nat](tg_alt Un (S i)) (S (mult (S (S O)) x))); Rewrite <- Rplus_Or. -Apply Rle_compatibility. -Unfold tg_alt; Simpl. -Replace (plus x (plus x O)) with (mult (2) x); [Idtac | Ring]. -Rewrite pow_1_even. -Replace `` -1*( -1*( -1*1))*(Un (S (S (S (mult (S (S O)) x)))))`` with ``-(Un (S (S (S (mult (S (S O)) x)))))``; [Idtac | Ring]. -Apply Rle_anti_compatibility with (Un (S (S (S (mult (S (S O)) x))))). -Rewrite Rplus_Or; Rewrite Rplus_Ropp_r. -Apply H0. -Apply CV_ALT_step2; Assumption. -Qed. - -(**********) -Lemma CV_ALT_step4 : (Un:nat->R) (Un_decreasing Un) -> (positivity_seq Un) -> (has_ub [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). -Intros; Unfold has_ub; Unfold bound. -Exists ``(Un O)``. -Unfold is_upper_bound; Intros; Elim H1; Intros. -Rewrite H2; Rewrite decomp_sum. -Replace (tg_alt Un O) with ``(Un O)``. -Pattern 2 ``(Un O)``; Rewrite <- Rplus_Or. -Apply Rle_compatibility. -Apply CV_ALT_step3; Assumption. -Unfold tg_alt; Simpl; Ring. -Apply lt_O_Sn. -Qed. - -(* This lemma gives an interesting result about alternated series *) -Lemma CV_ALT : (Un:nat->R) (Un_decreasing Un) -> (positivity_seq Un) -> (Un_cv Un R0) -> (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l)). -Intros. -Assert H2 := (CV_ALT_step0 ? H). -Assert H3 := (CV_ALT_step4 ? H H0). -Assert X := (growing_cv ? H2 H3). -Elim X; Intros. -Apply existTT with x. -Unfold Un_cv; Unfold R_dist; Unfold Un_cv in H1; Unfold R_dist in H1; Unfold Un_cv in p; Unfold R_dist in p. -Intros; Cut ``0<eps/2``; [Intro | Unfold Rdiv; Apply Rmult_lt_pos; [Assumption | Apply Rlt_Rinv; Sup0]]. -Elim (H1 ``eps/2`` H5); Intros N2 H6. -Elim (p ``eps/2`` H5); Intros N1 H7. -Pose N := (max (S (mult (2) N1)) N2). -Exists N; Intros. -Assert H9 := (even_odd_cor n). -Elim H9; Intros P H10. -Cut (le N1 P). -Intro; Elim H10; Intro. -Replace ``(sum_f_R0 (tg_alt Un) n)-x`` with ``((sum_f_R0 (tg_alt Un) (S n))-x)+(-(tg_alt Un (S n)))``. -Apply Rle_lt_trans with ``(Rabsolu ((sum_f_R0 (tg_alt Un) (S n))-x))+(Rabsolu (-(tg_alt Un (S n))))``. -Apply Rabsolu_triang. -Rewrite (double_var eps); Apply Rplus_lt. -Rewrite H12; Apply H7; Assumption. -Rewrite Rabsolu_Ropp; Unfold tg_alt; Rewrite Rabsolu_mult; Rewrite pow_1_abs; Rewrite Rmult_1l; Unfold Rminus in H6; Rewrite Ropp_O in H6; Rewrite <- (Rplus_Or (Un (S n))); Apply H6. -Unfold ge; Apply le_trans with n. -Apply le_trans with N; [Unfold N; Apply le_max_r | Assumption]. -Apply le_n_Sn. -Rewrite tech5; Ring. -Rewrite H12; Apply Rlt_trans with ``eps/2``. -Apply H7; Assumption. -Unfold Rdiv; Apply Rlt_monotony_contra with ``2``. -Sup0. -Rewrite (Rmult_sym ``2``); Rewrite Rmult_assoc; Rewrite <- Rinv_l_sym; [Rewrite Rmult_1r | DiscrR]. -Rewrite RIneq.double. -Pattern 1 eps; Rewrite <- (Rplus_Or eps); Apply Rlt_compatibility; Assumption. -Elim H10; Intro; Apply le_double. -Rewrite <- H11; Apply le_trans with N. -Unfold N; Apply le_trans with (S (mult (2) N1)); [Apply le_n_Sn | Apply le_max_l]. -Assumption. -Apply lt_n_Sm_le. -Rewrite <- H11. -Apply lt_le_trans with N. -Unfold N; Apply lt_le_trans with (S (mult (2) N1)). -Apply lt_n_Sn. -Apply le_max_l. -Assumption. -Qed. - -(************************************************) -(* Convergence of alternated series *) -(* *) -(* Applications: PI, cos, sin *) -(************************************************) -Theorem alternated_series : (Un:nat->R) (Un_decreasing Un) -> (Un_cv Un R0) -> (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l)). -Intros; Apply CV_ALT. -Assumption. -Unfold positivity_seq; Apply decreasing_ineq; Assumption. -Assumption. -Qed. - -Theorem alternated_series_ineq : (Un:nat->R;l:R;N:nat) (Un_decreasing Un) -> (Un_cv Un R0) -> (Un_cv [N:nat](sum_f_R0 (tg_alt Un) N) l) -> ``(sum_f_R0 (tg_alt Un) (S (mult (S (S O)) N)))<=l<=(sum_f_R0 (tg_alt Un) (mult (S (S O)) N))``. -Intros. -Cut (Un_cv [N:nat](sum_f_R0 (tg_alt Un) (mult (2) N)) l). -Cut (Un_cv [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N))) l). -Intros; Split. -Apply (growing_ineq [N:nat](sum_f_R0 (tg_alt Un) (S (mult (2) N)))). -Apply CV_ALT_step0; Assumption. -Assumption. -Apply (decreasing_ineq [N:nat](sum_f_R0 (tg_alt Un) (mult (2) N))). -Apply CV_ALT_step1; Assumption. -Assumption. -Unfold Un_cv; Unfold R_dist; Unfold Un_cv in H1; Unfold R_dist in H1; Intros. -Elim (H1 eps H2); Intros. -Exists x; Intros. -Apply H3. -Unfold ge; Apply le_trans with (mult (2) n). -Apply le_trans with n. -Assumption. -Assert H5 := (mult_O_le n (2)). -Elim H5; Intro. -Cut ~(O)=(2); [Intro; Elim H7; Symmetry; Assumption | Discriminate]. -Assumption. -Apply le_n_Sn. -Unfold Un_cv; Unfold R_dist; Unfold Un_cv in H1; Unfold R_dist in H1; Intros. -Elim (H1 eps H2); Intros. -Exists x; Intros. -Apply H3. -Unfold ge; Apply le_trans with n. -Assumption. -Assert H5 := (mult_O_le n (2)). -Elim H5; Intro. -Cut ~(O)=(2); [Intro; Elim H7; Symmetry; Assumption | Discriminate]. -Assumption. -Qed. - -(************************************) -(* Application : construction of PI *) -(************************************) - -Definition PI_tg := [n:nat]``/(INR (plus (mult (S (S O)) n) (S O)))``. - -Lemma PI_tg_pos : (n:nat)``0<=(PI_tg n)``. -Intro; Unfold PI_tg; Left; Apply Rlt_Rinv; Apply lt_INR_0; Replace (plus (mult (2) n) (1)) with (S (mult (2) n)); [Apply lt_O_Sn | Ring]. -Qed. - -Lemma PI_tg_decreasing : (Un_decreasing PI_tg). -Unfold PI_tg Un_decreasing; Intro. -Apply Rle_monotony_contra with ``(INR (plus (mult (S (S O)) n) (S O)))``. -Apply lt_INR_0. -Replace (plus (mult (2) n) (1)) with (S (mult (2) n)); [Apply lt_O_Sn | Ring]. -Rewrite <- Rinv_r_sym. -Apply Rle_monotony_contra with ``(INR (plus (mult (S (S O)) (S n)) (S O)))``. -Apply lt_INR_0. -Replace (plus (mult (2) (S n)) (1)) with (S (mult (2) (S n))); [Apply lt_O_Sn | Ring]. -Rewrite (Rmult_sym ``(INR (plus (mult (S (S O)) (S n)) (S O)))``); Rewrite Rmult_assoc; Rewrite <- Rinv_l_sym. -Do 2 Rewrite Rmult_1r; Apply le_INR. -Replace (plus (mult (2) (S n)) (1)) with (S (S (plus (mult (2) n) (1)))). -Apply le_trans with (S (plus (mult (2) n) (1))); Apply le_n_Sn. -Apply INR_eq; Do 2 Rewrite S_INR; Do 2 Rewrite plus_INR; Do 2 Rewrite mult_INR; Repeat Rewrite S_INR; Ring. -Apply not_O_INR; Discriminate. -Apply not_O_INR; Replace (plus (mult (2) n) (1)) with (S (mult (2) n)); [Discriminate | Ring]. -Qed. - -Lemma PI_tg_cv : (Un_cv PI_tg R0). -Unfold Un_cv; Unfold R_dist; Intros. -Cut ``0<2*eps``; [Intro | Apply Rmult_lt_pos; [Sup0 | Assumption]]. -Assert H1 := (archimed ``/(2*eps)``). -Cut (Zle `0` ``(up (/(2*eps)))``). -Intro; Assert H3 := (IZN ``(up (/(2*eps)))`` H2). -Elim H3; Intros N H4. -Cut (lt O N). -Intro; Exists N; Intros. -Cut (lt O n). -Intro; Unfold Rminus; Rewrite Ropp_O; Rewrite Rplus_Or; Rewrite Rabsolu_right. -Unfold PI_tg; Apply Rlt_trans with ``/(INR (mult (S (S O)) n))``. -Apply Rlt_monotony_contra with ``(INR (mult (S (S O)) n))``. -Apply lt_INR_0. -Replace (mult (2) n) with (plus n n); [Idtac | Ring]. -Apply lt_le_trans with n. -Assumption. -Apply le_plus_l. -Rewrite <- Rinv_r_sym. -Apply Rlt_monotony_contra with ``(INR (plus (mult (S (S O)) n) (S O)))``. -Apply lt_INR_0. -Replace (plus (mult (2) n) (1)) with (S (mult (2) n)); [Apply lt_O_Sn | Ring]. -Rewrite (Rmult_sym ``(INR (plus (mult (S (S O)) n) (S O)))``). -Rewrite Rmult_assoc; Rewrite <- Rinv_l_sym. -Do 2 Rewrite Rmult_1r; Apply lt_INR. -Replace (plus (mult (2) n) (1)) with (S (mult (2) n)); [Apply lt_n_Sn | Ring]. -Apply not_O_INR; Replace (plus (mult (2) n) (1)) with (S (mult (2) n)); [Discriminate | Ring]. -Replace n with (S (pred n)). -Apply not_O_INR; Discriminate. -Symmetry; Apply S_pred with O. -Assumption. -Apply Rle_lt_trans with ``/(INR (mult (S (S O)) N))``. -Apply Rle_monotony_contra with ``(INR (mult (S (S O)) N))``. -Rewrite mult_INR; Apply Rmult_lt_pos; [Simpl; Sup0 | Apply lt_INR_0; Assumption]. -Rewrite <- Rinv_r_sym. -Apply Rle_monotony_contra with ``(INR (mult (S (S O)) n))``. -Rewrite mult_INR; Apply Rmult_lt_pos; [Simpl; Sup0 | Apply lt_INR_0; Assumption]. -Rewrite (Rmult_sym (INR (mult (S (S O)) n))); Rewrite Rmult_assoc; Rewrite <- Rinv_l_sym. -Do 2 Rewrite Rmult_1r; Apply le_INR. -Apply mult_le; Assumption. -Replace n with (S (pred n)). -Apply not_O_INR; Discriminate. -Symmetry; Apply S_pred with O. -Assumption. -Replace N with (S (pred N)). -Apply not_O_INR; Discriminate. -Symmetry; Apply S_pred with O. -Assumption. -Rewrite mult_INR. -Rewrite Rinv_Rmult. -Replace (INR (S (S O))) with ``2``; [Idtac | Reflexivity]. -Apply Rlt_monotony_contra with ``2``. -Sup0. -Rewrite <- Rmult_assoc; Rewrite <- Rinv_r_sym; [Idtac | DiscrR]. -Rewrite Rmult_1l; Apply Rlt_monotony_contra with (INR N). -Apply lt_INR_0; Assumption. -Rewrite <- Rinv_r_sym. -Apply Rlt_monotony_contra with ``/(2*eps)``. -Apply Rlt_Rinv; Assumption. -Rewrite Rmult_1r; Replace ``/(2*eps)*((INR N)*(2*eps))`` with ``(INR N)*((2*eps)*/(2*eps))``; [Idtac | Ring]. -Rewrite <- Rinv_r_sym. -Rewrite Rmult_1r; Replace (INR N) with (IZR (INZ N)). -Rewrite <- H4. -Elim H1; Intros; Assumption. -Symmetry; Apply INR_IZR_INZ. -Apply prod_neq_R0; [DiscrR | Red; Intro; Rewrite H8 in H; Elim (Rlt_antirefl ? H)]. -Apply not_O_INR. -Red; Intro; Rewrite H8 in H5; Elim (lt_n_n ? H5). -Replace (INR (S (S O))) with ``2``; [DiscrR | Reflexivity]. -Apply not_O_INR. -Red; Intro; Rewrite H8 in H5; Elim (lt_n_n ? H5). -Apply Rle_sym1; Apply PI_tg_pos. -Apply lt_le_trans with N; Assumption. -Elim H1; Intros H5 _. -Assert H6 := (lt_eq_lt_dec O N). -Elim H6; Intro. -Elim a; Intro. -Assumption. -Rewrite <- b in H4. -Rewrite H4 in H5. -Simpl in H5. -Cut ``0</(2*eps)``; [Intro | Apply Rlt_Rinv; Assumption]. -Elim (Rlt_antirefl ? (Rlt_trans ? ? ? H7 H5)). -Elim (lt_n_O ? b). -Apply le_IZR. -Simpl. -Left; Apply Rlt_trans with ``/(2*eps)``. -Apply Rlt_Rinv; Assumption. -Elim H1; Intros; Assumption. -Qed. - -Lemma exist_PI : (sigTT R [l:R](Un_cv [N:nat](sum_f_R0 (tg_alt PI_tg) N) l)). -Apply alternated_series. -Apply PI_tg_decreasing. -Apply PI_tg_cv. -Qed. - -(* Now, PI is defined *) -Definition PI : R := (Rmult ``4`` (Cases exist_PI of (existTT a b) => a end)). - -(* We can get an approximation of PI with the following inequality *) -Lemma PI_ineq : (N:nat) ``(sum_f_R0 (tg_alt PI_tg) (S (mult (S (S O)) N)))<=PI/4<=(sum_f_R0 (tg_alt PI_tg) (mult (S (S O)) N))``. -Intro; Apply alternated_series_ineq. -Apply PI_tg_decreasing. -Apply PI_tg_cv. -Unfold PI; Case exist_PI; Intro. -Replace ``(4*x)/4`` with x. -Trivial. -Unfold Rdiv; Rewrite (Rmult_sym ``4``); Rewrite Rmult_assoc; Rewrite <- Rinv_r_sym; [Rewrite Rmult_1r; Reflexivity | DiscrR]. -Qed. - -Lemma PI_RGT_0 : ``0<PI``. -Assert H := (PI_ineq O). -Apply Rlt_monotony_contra with ``/4``. -Apply Rlt_Rinv; Sup0. -Rewrite Rmult_Or; Rewrite Rmult_sym. -Elim H; Clear H; Intros H _. -Unfold Rdiv in H; Apply Rlt_le_trans with ``(sum_f_R0 (tg_alt PI_tg) (S (mult (S (S O)) O)))``. -Simpl; Unfold tg_alt; Simpl; Rewrite Rmult_1l; Rewrite Rmult_1r; Apply Rlt_anti_compatibility with ``(PI_tg (S O))``. -Rewrite Rplus_Or; Replace ``(PI_tg (S O))+((PI_tg O)+ -1*(PI_tg (S O)))`` with ``(PI_tg O)``; [Unfold PI_tg | Ring]. -Simpl; Apply Rinv_lt. -Rewrite Rmult_1l; Replace ``2+1`` with ``3``; [Sup0 | Ring]. -Rewrite Rplus_sym; Pattern 1 R1; Rewrite <- Rplus_Or; Apply Rlt_compatibility; Sup0. -Assumption. -Qed. |