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Diffstat (limited to 'theories/Numbers/Cyclic/DoubleCyclic/DoubleLift.v')
| -rw-r--r-- | theories/Numbers/Cyclic/DoubleCyclic/DoubleLift.v | 475 |
1 files changed, 0 insertions, 475 deletions
diff --git a/theories/Numbers/Cyclic/DoubleCyclic/DoubleLift.v b/theories/Numbers/Cyclic/DoubleCyclic/DoubleLift.v deleted file mode 100644 index f65b47c8..00000000 --- a/theories/Numbers/Cyclic/DoubleCyclic/DoubleLift.v +++ /dev/null @@ -1,475 +0,0 @@ -(************************************************************************) -(* v * The Coq Proof Assistant / The Coq Development Team *) -(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2016 *) -(* \VV/ **************************************************************) -(* // * This file is distributed under the terms of the *) -(* * GNU Lesser General Public License Version 2.1 *) -(************************************************************************) -(* Benjamin Gregoire, Laurent Thery, INRIA, 2007 *) -(************************************************************************) - -Set Implicit Arguments. - -Require Import ZArith. -Require Import BigNumPrelude. -Require Import DoubleType. -Require Import DoubleBase. - -Local Open Scope Z_scope. - -Section DoubleLift. - Variable w : Type. - Variable w_0 : w. - Variable w_WW : w -> w -> zn2z w. - Variable w_W0 : w -> zn2z w. - Variable w_0W : w -> zn2z w. - Variable w_compare : w -> w -> comparison. - Variable ww_compare : zn2z w -> zn2z w -> comparison. - Variable w_head0 : w -> w. - Variable w_tail0 : w -> w. - Variable w_add: w -> w -> zn2z w. - Variable w_add_mul_div : w -> w -> w -> w. - Variable ww_sub: zn2z w -> zn2z w -> zn2z w. - Variable w_digits : positive. - Variable ww_Digits : positive. - Variable w_zdigits : w. - Variable ww_zdigits : zn2z w. - Variable low: zn2z w -> w. - - Definition ww_head0 x := - match x with - | W0 => ww_zdigits - | WW xh xl => - match w_compare w_0 xh with - | Eq => w_add w_zdigits (w_head0 xl) - | _ => w_0W (w_head0 xh) - end - end. - - - Definition ww_tail0 x := - match x with - | W0 => ww_zdigits - | WW xh xl => - match w_compare w_0 xl with - | Eq => w_add w_zdigits (w_tail0 xh) - | _ => w_0W (w_tail0 xl) - end - end. - - - (* 0 < p < ww_digits *) - Definition ww_add_mul_div p x y := - let zdigits := w_0W w_zdigits in - match x, y with - | W0, W0 => W0 - | W0, WW yh yl => - match ww_compare p zdigits with - | Eq => w_0W yh - | Lt => w_0W (w_add_mul_div (low p) w_0 yh) - | Gt => - let n := low (ww_sub p zdigits) in - w_WW (w_add_mul_div n w_0 yh) (w_add_mul_div n yh yl) - end - | WW xh xl, W0 => - match ww_compare p zdigits with - | Eq => w_W0 xl - | Lt => w_WW (w_add_mul_div (low p) xh xl) (w_add_mul_div (low p) xl w_0) - | Gt => - let n := low (ww_sub p zdigits) in - w_W0 (w_add_mul_div n xl w_0) - end - | WW xh xl, WW yh yl => - match ww_compare p zdigits with - | Eq => w_WW xl yh - | Lt => w_WW (w_add_mul_div (low p) xh xl) (w_add_mul_div (low p) xl yh) - | Gt => - let n := low (ww_sub p zdigits) in - w_WW (w_add_mul_div n xl yh) (w_add_mul_div n yh yl) - end - end. - - Section DoubleProof. - Variable w_to_Z : w -> Z. - - Notation wB := (base w_digits). - Notation wwB := (base (ww_digits w_digits)). - Notation "[| x |]" := (w_to_Z x) (at level 0, x at level 99). - Notation "[[ x ]]" := (ww_to_Z w_digits w_to_Z x)(at level 0, x at level 99). - - Variable spec_w_0 : [|w_0|] = 0. - Variable spec_to_Z : forall x, 0 <= [|x|] < wB. - Variable spec_to_w_Z : forall x, 0 <= [[x]] < wwB. - Variable spec_w_WW : forall h l, [[w_WW h l]] = [|h|] * wB + [|l|]. - Variable spec_w_W0 : forall h, [[w_W0 h]] = [|h|] * wB. - Variable spec_w_0W : forall l, [[w_0W l]] = [|l|]. - Variable spec_compare : forall x y, - w_compare x y = Z.compare [|x|] [|y|]. - Variable spec_ww_compare : forall x y, - ww_compare x y = Z.compare [[x]] [[y]]. - Variable spec_ww_digits : ww_Digits = xO w_digits. - Variable spec_w_head00 : forall x, [|x|] = 0 -> [|w_head0 x|] = Zpos w_digits. - Variable spec_w_head0 : forall x, 0 < [|x|] -> - wB/ 2 <= 2 ^ ([|w_head0 x|]) * [|x|] < wB. - Variable spec_w_tail00 : forall x, [|x|] = 0 -> [|w_tail0 x|] = Zpos w_digits. - Variable spec_w_tail0 : forall x, 0 < [|x|] -> - exists y, 0 <= y /\ [|x|] = (2* y + 1) * (2 ^ [|w_tail0 x|]). - Variable spec_w_add_mul_div : forall x y p, - [|p|] <= Zpos w_digits -> - [| w_add_mul_div p x y |] = - ([|x|] * (2 ^ [|p|]) + - [|y|] / (2 ^ ((Zpos w_digits) - [|p|]))) mod wB. - Variable spec_w_add: forall x y, - [[w_add x y]] = [|x|] + [|y|]. - Variable spec_ww_sub: forall x y, - [[ww_sub x y]] = ([[x]] - [[y]]) mod wwB. - - Variable spec_zdigits : [| w_zdigits |] = Zpos w_digits. - Variable spec_low: forall x, [| low x|] = [[x]] mod wB. - - Variable spec_ww_zdigits : [[ww_zdigits]] = Zpos ww_Digits. - - Hint Resolve div_le_0 div_lt w_to_Z_wwB: lift. - Ltac zarith := auto with zarith lift. - - Lemma spec_ww_head00 : forall x, [[x]] = 0 -> [[ww_head0 x]] = Zpos ww_Digits. - Proof. - intros x; case x; unfold ww_head0. - intros HH; rewrite spec_ww_zdigits; auto. - intros xh xl; simpl; intros Hx. - case (spec_to_Z xh); intros Hx1 Hx2. - case (spec_to_Z xl); intros Hy1 Hy2. - assert (F1: [|xh|] = 0). - { Z.le_elim Hy1; auto. - - absurd (0 < [|xh|] * wB + [|xl|]); auto with zarith. - apply Z.lt_le_trans with (1 := Hy1); auto with zarith. - pattern [|xl|] at 1; rewrite <- (Z.add_0_l [|xl|]). - apply Z.add_le_mono_r; auto with zarith. - - Z.le_elim Hx1; auto. - absurd (0 < [|xh|] * wB + [|xl|]); auto with zarith. - rewrite <- Hy1; rewrite Z.add_0_r; auto with zarith. - apply Z.mul_pos_pos; auto with zarith. } - rewrite spec_compare. case Z.compare_spec. - intros H; simpl. - rewrite spec_w_add; rewrite spec_w_head00. - rewrite spec_zdigits; rewrite spec_ww_digits. - rewrite Pos2Z.inj_xO; auto with zarith. - rewrite F1 in Hx; auto with zarith. - rewrite spec_w_0; auto with zarith. - rewrite spec_w_0; auto with zarith. - Qed. - - Lemma spec_ww_head0 : forall x, 0 < [[x]] -> - wwB/ 2 <= 2 ^ [[ww_head0 x]] * [[x]] < wwB. - Proof. - clear spec_ww_zdigits. - rewrite wwB_div_2;rewrite Z.mul_comm;rewrite wwB_wBwB. - assert (U:= lt_0_wB w_digits); destruct x as [ |xh xl];simpl ww_to_Z;intros H. - unfold Z.lt in H;discriminate H. - rewrite spec_compare, spec_w_0. case Z.compare_spec; intros H0. - rewrite <- H0 in *. simpl Z.add. simpl in H. - case (spec_to_Z w_zdigits); - case (spec_to_Z (w_head0 xl)); intros HH1 HH2 HH3 HH4. - rewrite spec_w_add. - rewrite spec_zdigits; rewrite Zpower_exp; auto with zarith. - case (spec_w_head0 H); intros H1 H2. - rewrite Z.pow_2_r; fold wB; rewrite <- Z.mul_assoc; split. - apply Z.mul_le_mono_nonneg_l; auto with zarith. - apply Z.mul_lt_mono_pos_l; auto with zarith. - assert (H1 := spec_w_head0 H0). - rewrite spec_w_0W. - split. - rewrite Z.mul_add_distr_l;rewrite Z.mul_assoc. - apply Z.le_trans with (2 ^ [|w_head0 xh|] * [|xh|] * wB). - rewrite Z.mul_comm; zarith. - assert (0 <= 2 ^ [|w_head0 xh|] * [|xl|]);zarith. - assert (H2:=spec_to_Z xl);apply Z.mul_nonneg_nonneg;zarith. - case (spec_to_Z (w_head0 xh)); intros H2 _. - generalize ([|w_head0 xh|]) H1 H2;clear H1 H2; - intros p H1 H2. - assert (Eq1 : 2^p < wB). - rewrite <- (Z.mul_1_r (2^p));apply Z.le_lt_trans with (2^p*[|xh|]);zarith. - assert (Eq2: p < Zpos w_digits). - destruct (Z.le_gt_cases (Zpos w_digits) p);trivial;contradict Eq1. - apply Z.le_ngt;unfold base;apply Zpower_le_monotone;zarith. - assert (Zpos w_digits = p + (Zpos w_digits - p)). ring. - rewrite Z.pow_2_r. - unfold base at 2;rewrite H3;rewrite Zpower_exp;zarith. - rewrite <- Z.mul_assoc; apply Z.mul_lt_mono_pos_l; zarith. - rewrite <- (Z.add_0_r (2^(Zpos w_digits - p)*wB));apply beta_lex_inv;zarith. - apply Z.mul_lt_mono_pos_r with (2 ^ p); zarith. - rewrite <- Zpower_exp;zarith. - rewrite Z.mul_comm;ring_simplify (Zpos w_digits - p + p);fold wB;zarith. - assert (H1 := spec_to_Z xh);zarith. - Qed. - - Lemma spec_ww_tail00 : forall x, [[x]] = 0 -> [[ww_tail0 x]] = Zpos ww_Digits. - Proof. - intros x; case x; unfold ww_tail0. - intros HH; rewrite spec_ww_zdigits; auto. - intros xh xl; simpl; intros Hx. - case (spec_to_Z xh); intros Hx1 Hx2. - case (spec_to_Z xl); intros Hy1 Hy2. - assert (F1: [|xh|] = 0). - { Z.le_elim Hy1; auto. - - absurd (0 < [|xh|] * wB + [|xl|]); auto with zarith. - apply Z.lt_le_trans with (1 := Hy1); auto with zarith. - pattern [|xl|] at 1; rewrite <- (Z.add_0_l [|xl|]). - apply Z.add_le_mono_r; auto with zarith. - - Z.le_elim Hx1; auto. - absurd (0 < [|xh|] * wB + [|xl|]); auto with zarith. - rewrite <- Hy1; rewrite Z.add_0_r; auto with zarith. - apply Z.mul_pos_pos; auto with zarith. } - assert (F2: [|xl|] = 0). - rewrite F1 in Hx; auto with zarith. - rewrite spec_compare; case Z.compare_spec. - intros H; simpl. - rewrite spec_w_add; rewrite spec_w_tail00; auto. - rewrite spec_zdigits; rewrite spec_ww_digits. - rewrite Pos2Z.inj_xO; auto with zarith. - rewrite spec_w_0; auto with zarith. - rewrite spec_w_0; auto with zarith. - Qed. - - Lemma spec_ww_tail0 : forall x, 0 < [[x]] -> - exists y, 0 <= y /\ [[x]] = (2 * y + 1) * 2 ^ [[ww_tail0 x]]. - Proof. - clear spec_ww_zdigits. - destruct x as [ |xh xl];simpl ww_to_Z;intros H. - unfold Z.lt in H;discriminate H. - rewrite spec_compare, spec_w_0. case Z.compare_spec; intros H0. - rewrite <- H0; rewrite Z.add_0_r. - case (spec_to_Z (w_tail0 xh)); intros HH1 HH2. - generalize H; rewrite <- H0; rewrite Z.add_0_r; clear H; intros H. - case (@spec_w_tail0 xh). - apply Z.mul_lt_mono_pos_r with wB; auto with zarith. - unfold base; auto with zarith. - intros z (Hz1, Hz2); exists z; split; auto. - rewrite spec_w_add; rewrite (fun x => Z.add_comm [|x|]). - rewrite spec_zdigits; rewrite Zpower_exp; auto with zarith. - rewrite Z.mul_assoc; rewrite <- Hz2; auto. - - case (spec_to_Z (w_tail0 xh)); intros HH1 HH2. - case (spec_w_tail0 H0); intros z (Hz1, Hz2). - assert (Hp: [|w_tail0 xl|] < Zpos w_digits). - case (Z.le_gt_cases (Zpos w_digits) [|w_tail0 xl|]); auto; intros H1. - absurd (2 ^ (Zpos w_digits) <= 2 ^ [|w_tail0 xl|]). - apply Z.lt_nge. - case (spec_to_Z xl); intros HH3 HH4. - apply Z.le_lt_trans with (2 := HH4). - apply Z.le_trans with (1 * 2 ^ [|w_tail0 xl|]); auto with zarith. - rewrite Hz2. - apply Z.mul_le_mono_nonneg_r; auto with zarith. - apply Zpower_le_monotone; auto with zarith. - exists ([|xh|] * (2 ^ ((Zpos w_digits - [|w_tail0 xl|]) - 1)) + z); split. - apply Z.add_nonneg_nonneg; auto. - apply Z.mul_nonneg_nonneg; auto with zarith. - case (spec_to_Z xh); auto. - rewrite spec_w_0W. - rewrite (Z.mul_add_distr_l 2); rewrite <- Z.add_assoc. - rewrite Z.mul_add_distr_r; rewrite <- Hz2. - apply f_equal2 with (f := Z.add); auto. - rewrite (Z.mul_comm 2). - repeat rewrite <- Z.mul_assoc. - apply f_equal2 with (f := Z.mul); auto. - case (spec_to_Z (w_tail0 xl)); intros HH3 HH4. - pattern 2 at 2; rewrite <- Z.pow_1_r. - lazy beta; repeat rewrite <- Zpower_exp; auto with zarith. - unfold base; apply f_equal with (f := Z.pow 2); auto with zarith. - - contradict H0; case (spec_to_Z xl); auto with zarith. - Qed. - - Hint Rewrite Zdiv_0_l Z.mul_0_l Z.add_0_l Z.mul_0_r Z.add_0_r - spec_w_W0 spec_w_0W spec_w_WW spec_w_0 - (wB_div w_digits w_to_Z spec_to_Z) - (wB_div_plus w_digits w_to_Z spec_to_Z) : w_rewrite. - Ltac w_rewrite := autorewrite with w_rewrite;trivial. - - Lemma spec_ww_add_mul_div_aux : forall xh xl yh yl p, - let zdigits := w_0W w_zdigits in - [[p]] <= Zpos (xO w_digits) -> - [[match ww_compare p zdigits with - | Eq => w_WW xl yh - | Lt => w_WW (w_add_mul_div (low p) xh xl) - (w_add_mul_div (low p) xl yh) - | Gt => - let n := low (ww_sub p zdigits) in - w_WW (w_add_mul_div n xl yh) (w_add_mul_div n yh yl) - end]] = - ([[WW xh xl]] * (2^[[p]]) + - [[WW yh yl]] / (2^(Zpos (xO w_digits) - [[p]]))) mod wwB. - Proof. - clear spec_ww_zdigits. - intros xh xl yh yl p zdigits;assert (HwwB := wwB_pos w_digits). - case (spec_to_w_Z p); intros Hv1 Hv2. - replace (Zpos (xO w_digits)) with (Zpos w_digits + Zpos w_digits). - 2 : rewrite Pos2Z.inj_xO;ring. - replace (Zpos w_digits + Zpos w_digits - [[p]]) with - (Zpos w_digits + (Zpos w_digits - [[p]])). 2:ring. - intros Hp; assert (Hxh := spec_to_Z xh);assert (Hxl:=spec_to_Z xl); - assert (Hx := spec_ww_to_Z w_digits w_to_Z spec_to_Z (WW xh xl)); - simpl in Hx;assert (Hyh := spec_to_Z yh);assert (Hyl:=spec_to_Z yl); - assert (Hy:=spec_ww_to_Z w_digits w_to_Z spec_to_Z (WW yh yl));simpl in Hy. - rewrite spec_ww_compare; case Z.compare_spec; intros H1. - rewrite H1; unfold zdigits; rewrite spec_w_0W. - rewrite spec_zdigits; rewrite Z.sub_diag; rewrite Z.add_0_r. - simpl ww_to_Z; w_rewrite;zarith. - fold wB. - rewrite Z.mul_add_distr_r;rewrite <- Z.mul_assoc;rewrite <- Z.add_assoc. - rewrite <- Z.pow_2_r. - rewrite <- wwB_wBwB;apply Zmod_unique with [|xh|]. - exact (spec_ww_to_Z w_digits w_to_Z spec_to_Z (WW xl yh)). ring. - simpl ww_to_Z; w_rewrite;zarith. - assert (HH0: [|low p|] = [[p]]). - rewrite spec_low. - apply Zmod_small. - case (spec_to_w_Z p); intros HH1 HH2; split; auto. - generalize H1; unfold zdigits; rewrite spec_w_0W; - rewrite spec_zdigits; intros tmp. - apply Z.lt_le_trans with (1 := tmp). - unfold base. - apply Zpower2_le_lin; auto with zarith. - 2: generalize H1; unfold zdigits; rewrite spec_w_0W; - rewrite spec_zdigits; auto with zarith. - generalize H1; unfold zdigits; rewrite spec_w_0W; - rewrite spec_zdigits; auto; clear H1; intros H1. - assert (HH: [|low p|] <= Zpos w_digits). - rewrite HH0; auto with zarith. - repeat rewrite spec_w_add_mul_div with (1 := HH). - rewrite HH0. - rewrite Z.mul_add_distr_r. - pattern ([|xl|] * 2 ^ [[p]]) at 2; - rewrite shift_unshift_mod with (n:= Zpos w_digits);fold wB;zarith. - replace ([|xh|] * wB * 2^[[p]]) with ([|xh|] * 2^[[p]] * wB). 2:ring. - rewrite Z.add_assoc;rewrite <- Z.mul_add_distr_r. rewrite <- Z.add_assoc. - unfold base at 5;rewrite <- Zmod_shift_r;zarith. - unfold base;rewrite Zmod_shift_r with (b:= Zpos (ww_digits w_digits)); - fold wB;fold wwB;zarith. - rewrite wwB_wBwB;rewrite Z.pow_2_r; rewrite Zmult_mod_distr_r;zarith. - unfold ww_digits;rewrite Pos2Z.inj_xO;zarith. apply Z_mod_lt;zarith. - split;zarith. apply Zdiv_lt_upper_bound;zarith. - rewrite <- Zpower_exp;zarith. - ring_simplify ([[p]] + (Zpos w_digits - [[p]]));fold wB;zarith. - assert (Hv: [[p]] > Zpos w_digits). - generalize H1; clear H1. - unfold zdigits; rewrite spec_w_0W; rewrite spec_zdigits; auto with zarith. - clear H1. - assert (HH0: [|low (ww_sub p zdigits)|] = [[p]] - Zpos w_digits). - rewrite spec_low. - rewrite spec_ww_sub. - unfold zdigits; rewrite spec_w_0W; rewrite spec_zdigits. - rewrite <- Zmod_div_mod; auto with zarith. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - apply Z.le_lt_trans with (Zpos w_digits); auto with zarith. - unfold base; apply Zpower2_lt_lin; auto with zarith. - exists wB; unfold base. - unfold ww_digits; rewrite (Pos2Z.inj_xO w_digits). - rewrite <- Zpower_exp; auto with zarith. - apply f_equal with (f := fun x => 2 ^ x); auto with zarith. - assert (HH: [|low (ww_sub p zdigits)|] <= Zpos w_digits). - rewrite HH0; auto with zarith. - replace (Zpos w_digits + (Zpos w_digits - [[p]])) with - (Zpos w_digits - ([[p]] - Zpos w_digits)); zarith. - lazy zeta; simpl ww_to_Z; w_rewrite;zarith. - repeat rewrite spec_w_add_mul_div;zarith. - rewrite HH0. - pattern wB at 5;replace wB with - (2^(([[p]] - Zpos w_digits) - + (Zpos w_digits - ([[p]] - Zpos w_digits)))). - rewrite Zpower_exp;zarith. rewrite Z.mul_assoc. - rewrite Z_div_plus_l;zarith. - rewrite shift_unshift_mod with (a:= [|yh|]) (p:= [[p]] - Zpos w_digits) - (n := Zpos w_digits);zarith. fold wB. - set (u := [[p]] - Zpos w_digits). - replace [[p]] with (u + Zpos w_digits);zarith. - rewrite Zpower_exp;zarith. rewrite Z.mul_assoc. fold wB. - repeat rewrite Z.add_assoc. rewrite <- Z.mul_add_distr_r. - repeat rewrite <- Z.add_assoc. - unfold base;rewrite Zmod_shift_r with (b:= Zpos (ww_digits w_digits)); - fold wB;fold wwB;zarith. - unfold base;rewrite Zmod_shift_r with (a:= Zpos w_digits) - (b:= Zpos w_digits);fold wB;fold wwB;zarith. - rewrite wwB_wBwB; rewrite Z.pow_2_r; rewrite Zmult_mod_distr_r;zarith. - rewrite Z.mul_add_distr_r. - replace ([|xh|] * wB * 2 ^ u) with - ([|xh|]*2^u*wB). 2:ring. - repeat rewrite <- Z.add_assoc. - rewrite (Z.add_comm ([|xh|] * 2 ^ u * wB)). - rewrite Z_mod_plus;zarith. rewrite Z_mod_mult;zarith. - unfold base;rewrite <- Zmod_shift_r;zarith. fold base;apply Z_mod_lt;zarith. - unfold u; split;zarith. - split;zarith. unfold u; apply Zdiv_lt_upper_bound;zarith. - rewrite <- Zpower_exp;zarith. - fold u. - ring_simplify (u + (Zpos w_digits - u)); fold - wB;zarith. unfold ww_digits;rewrite Pos2Z.inj_xO;zarith. - unfold base;rewrite <- Zmod_shift_r;zarith. fold base;apply Z_mod_lt;zarith. - unfold u; split;zarith. - unfold u; split;zarith. - apply Zdiv_lt_upper_bound;zarith. - rewrite <- Zpower_exp;zarith. - fold u. - ring_simplify (u + (Zpos w_digits - u)); fold wB; auto with zarith. - unfold u;zarith. - unfold u;zarith. - set (u := [[p]] - Zpos w_digits). - ring_simplify (u + (Zpos w_digits - u)); fold wB; auto with zarith. - Qed. - - Lemma spec_ww_add_mul_div : forall x y p, - [[p]] <= Zpos (xO w_digits) -> - [[ ww_add_mul_div p x y ]] = - ([[x]] * (2^[[p]]) + - [[y]] / (2^(Zpos (xO w_digits) - [[p]]))) mod wwB. - Proof. - clear spec_ww_zdigits. - intros x y p H. - destruct x as [ |xh xl]; - [assert (H1 := @spec_ww_add_mul_div_aux w_0 w_0) - |assert (H1 := @spec_ww_add_mul_div_aux xh xl)]; - (destruct y as [ |yh yl]; - [generalize (H1 w_0 w_0 p H) | generalize (H1 yh yl p H)]; - clear H1;w_rewrite);simpl ww_add_mul_div. - replace [[WW w_0 w_0]] with 0;[w_rewrite|simpl;w_rewrite;trivial]. - intros Heq;rewrite <- Heq;clear Heq; auto. - rewrite spec_ww_compare. case Z.compare_spec; intros H1; w_rewrite. - rewrite (spec_w_add_mul_div w_0 w_0);w_rewrite;zarith. - generalize H1; w_rewrite; rewrite spec_zdigits; clear H1; intros H1. - assert (HH0: [|low p|] = [[p]]). - rewrite spec_low. - apply Zmod_small. - case (spec_to_w_Z p); intros HH1 HH2; split; auto. - apply Z.lt_le_trans with (1 := H1). - unfold base; apply Zpower2_le_lin; auto with zarith. - rewrite HH0; auto with zarith. - replace [[WW w_0 w_0]] with 0;[w_rewrite|simpl;w_rewrite;trivial]. - intros Heq;rewrite <- Heq;clear Heq. - generalize (spec_ww_compare p (w_0W w_zdigits)); - case ww_compare; intros H1; w_rewrite. - rewrite (spec_w_add_mul_div w_0 w_0);w_rewrite;zarith. - rewrite Pos2Z.inj_xO in H;zarith. - assert (HH: [|low (ww_sub p (w_0W w_zdigits)) |] = [[p]] - Zpos w_digits). - symmetry in H1; change ([[p]] > [[w_0W w_zdigits]]) in H1. - revert H1. - rewrite spec_low. - rewrite spec_ww_sub; w_rewrite; intros H1. - rewrite <- Zmod_div_mod; auto with zarith. - rewrite Zmod_small; auto with zarith. - split; auto with zarith. - apply Z.le_lt_trans with (Zpos w_digits); auto with zarith. - unfold base; apply Zpower2_lt_lin; auto with zarith. - unfold base; auto with zarith. - unfold base; auto with zarith. - exists wB; unfold base. - unfold ww_digits; rewrite (Pos2Z.inj_xO w_digits). - rewrite <- Zpower_exp; auto with zarith. - apply f_equal with (f := fun x => 2 ^ x); auto with zarith. - case (spec_to_Z xh); auto with zarith. - Qed. - - End DoubleProof. - -End DoubleLift. - |