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eqp_rdiv_divp q : rdivp p q %= divp p q. Proof. rewrite divpE eqp_sym; case: ifP=> ulcq//; apply: eqp_scale; rewrite invr_eq0//. by apply: expf_neq0; apply: contraTneq ulcq => ->; rewrite unitr0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eqp_rdiv_div
dvd_eqp_divld p q (dvd_dp : d %| q) (eq_pq : p %= q) : p %/ d %= q %/ d. Proof. case: (eqVneq q 0) eq_pq=> [->|q_neq0]; first by rewrite eqp0=> /eqP->. have d_neq0: d != 0 by apply: contraTneq dvd_dp=> ->; rewrite dvd0p. move=> eq_pq; rewrite -(@eqp_mul2r d) // !divpK // ?(eqp_dvdr _ eq_pq) //. rewrite (eqp_ltrans (eqp_scale _ _)) ?lc_expn_scalp_neq0 //. by rewrite (eqp_rtrans (eqp_scale _ _)) ?lc_expn_scalp_neq0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvd_eqp_divl
gcdpp q := let: (p1, q1) := if size p < size q then (q, p) else (p, q) in if p1 == 0 then q1 else let fix loop (n : nat) (pp qq : {poly R}) {struct n} := let rr := modp pp qq in if rr == 0 then qq else if n is n1.+1 then loop n1 qq rr else rr in loop (size p1) p1 q1. Arguments gcdp : simpl never.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp
gcd0p: left_id 0 gcdp. Proof. move=> p; rewrite /gcdp size_poly0 size_poly_gt0 if_neg. case: ifP => /= [_ | nzp]; first by rewrite eqxx. by rewrite polySpred !(modp0, nzp) //; case: _.-1 => [|m]; rewrite mod0p eqxx. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcd0p
gcdp0: right_id 0 gcdp. Proof. move=> p; have:= gcd0p p; rewrite /gcdp size_poly0 size_poly_gt0. by case: eqVneq => //= ->; rewrite eqxx. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp0
gcdpEp q : gcdp p q = if size p < size q then gcdp (modp q p) p else gcdp (modp p q) q. Proof. pose gcdpE_rec := fix gcdpE_rec (n : nat) (pp qq : {poly R}) {struct n} := let rr := modp pp qq in if rr == 0 then qq else if n is n1.+1 then gcdpE_rec n1 qq rr else rr. have Irec: forall k l p q, size q <= k -> size q <= l -> size q < size p -> gcdpE_rec k p q = gcdpE_rec l p q. + elim=> [|m Hrec] [|n] //= p1 q1. - move/size_poly_leq0P=> -> _; rewrite size_poly0 size_poly_gt0 modp0. by move/negPf ->; case: n => [|n] /=; rewrite mod0p eqxx. - move=> _ /size_poly_leq0P ->; rewrite size_poly0 size_poly_gt0 modp0. by move/negPf ->; case: m {Hrec} => [|m] /=; rewrite mod0p eqxx. case: eqP => Epq Sm Sn Sq //; have [->|nzq] := eqVneq q1 0. by case: n m {Sm Sn Hrec} => [|m] [|n] //=; rewrite mod0p eqxx. apply: Hrec; last by rewrite ltn_modp. by rewrite -ltnS (leq_trans _ Sm) // ltn_modp. by rewrite -ltnS (leq_trans _ Sn) // ltn_modp. have [->|nzp] := eqVneq p 0; first by rewrite mod0p modp0 gcd0p gcdp0 if_same. have [->|nzq] := eqVneq q 0; first by rewrite mod0p modp0 gcd0p gcdp0 if_same. rewrite /gcdp !ltn_modp !(negPf nzp, negPf nzq) /=. have [ltpq|leqp] := ltnP; rewrite !(negPf nzp, negPf nzq) /= polySpred //. have [->|nzqp] := eqVneq. by case: (size p) => [|[|s]]; rewrite /= modp0 (negPf nzp) // mod0p eqxx. apply: Irec => //; last by rewrite ltn_modp. by rewrite -ltnS -polySpred // (leq_trans _ ltpq) ?leqW // ltn_modp. by rewrite ...
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdpE
size_gcd1pp : size (gcdp 1 p) = 1. Proof. rewrite gcdpE size_polyC oner_eq0 /= modp1; have [|/size1_polyC ->] := ltnP. by rewrite gcd0p size_polyC oner_eq0. have [->|p00] := eqVneq p`_0 0; first by rewrite modp0 gcdp0 size_poly1. by rewrite modpC // gcd0p size_polyC p00. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
size_gcd1p
size_gcdp1p : size (gcdp p 1) = 1. Proof. rewrite gcdpE size_polyC oner_eq0 /= modp1 ltnS; case: leqP. by move/size_poly_leq0P->; rewrite gcdp0 modp0 size_polyC oner_eq0. by rewrite gcd0p size_polyC oner_eq0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
size_gcdp1
gcdpp: idempotent_op gcdp. Proof. by move=> p; rewrite gcdpE ltnn modpp gcd0p. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdpp
dvdp_gcdlrp q : (gcdp p q %| p) && (gcdp p q %| q). Proof. have [r] := ubnP (minn (size q) (size p)); elim: r => // r IHr in p q *. have [-> | nz_p] := eqVneq p 0; first by rewrite gcd0p dvdpp andbT. have [-> | nz_q] := eqVneq q 0; first by rewrite gcdp0 dvdpp /=. rewrite ltnS gcdpE; case: leqP => [le_pq | lt_pq] le_qr. suffices /IHr/andP[E1 E2]: minn (size q) (size (p %% q)) < r. by rewrite E2 andbT (dvdp_mod _ E2). by rewrite gtn_min orbC (leq_trans _ le_qr) ?ltn_modp. suffices /IHr/andP[E1 E2]: minn (size p) (size (q %% p)) < r. by rewrite E2 (dvdp_mod _ E2). by rewrite gtn_min orbC (leq_trans _ le_qr) ?ltn_modp. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_gcdlr
dvdp_gcdlp q : gcdp p q %| p. Proof. by case/andP: (dvdp_gcdlr p q). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_gcdl
dvdp_gcdrp q :gcdp p q %| q. Proof. by case/andP: (dvdp_gcdlr p q). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_gcdr
leq_gcdplp q : p != 0 -> size (gcdp p q) <= size p. Proof. by move=> pn0; move: (dvdp_gcdl p q); apply: dvdp_leq. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
leq_gcdpl
leq_gcdprp q : q != 0 -> size (gcdp p q) <= size q. Proof. by move=> qn0; move: (dvdp_gcdr p q); apply: dvdp_leq. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
leq_gcdpr
dvdp_gcdp m n : p %| gcdp m n = (p %| m) && (p %| n). Proof. apply/idP/andP=> [dv_pmn | []]. by rewrite ?(dvdp_trans dv_pmn) ?dvdp_gcdl ?dvdp_gcdr. have [r] := ubnP (minn (size n) (size m)); elim: r => // r IHr in m n *. have [-> | nz_m] := eqVneq m 0; first by rewrite gcd0p. have [-> | nz_n] := eqVneq n 0; first by rewrite gcdp0. rewrite gcdpE ltnS; case: leqP => [le_nm | lt_mn] le_r dv_m dv_n. apply: IHr => //; last by rewrite -(dvdp_mod _ dv_n). by rewrite gtn_min orbC (leq_trans _ le_r) ?ltn_modp. apply: IHr => //; last by rewrite -(dvdp_mod _ dv_m). by rewrite gtn_min orbC (leq_trans _ le_r) ?ltn_modp. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_gcd
gcdpCp q : gcdp p q %= gcdp q p. Proof. by rewrite /eqp !dvdp_gcd !dvdp_gcdl !dvdp_gcdr. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdpC
gcd1pp : gcdp 1 p %= 1. Proof. rewrite -size_poly_eq1 gcdpE size_poly1; case: ltnP. by rewrite modp1 gcd0p size_poly1 eqxx. move/size1_polyC=> e; rewrite e. have [->|p00] := eqVneq p`_0 0; first by rewrite modp0 gcdp0 size_poly1. by rewrite modpC // gcd0p size_polyC p00. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcd1p
gcdp1p : gcdp p 1 %= 1. Proof. by rewrite (eqp_ltrans (gcdpC _ _)) gcd1p. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp1
gcdp_addl_mulp q r: gcdp r (p * r + q) %= gcdp r q. Proof. suff h m n d : gcdp d n %| gcdp d (m * d + n). apply/andP; split => //. by rewrite {2}(_: q = (-p) * r + (p * r + q)) ?H // mulNr addKr. by rewrite dvdp_gcd dvdp_gcdl /= dvdp_addr ?dvdp_gcdr ?dvdp_mull ?dvdp_gcdl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_addl_mul
gcdp_addlm n : gcdp m (m + n) %= gcdp m n. Proof. by rewrite -[m in m + _]mul1r gcdp_addl_mul. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_addl
gcdp_addrm n : gcdp m (n + m) %= gcdp m n. Proof. by rewrite addrC gcdp_addl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_addr
gcdp_mullm n : gcdp n (m * n) %= n. Proof. have [-> | nn0] := eqVneq n 0; first by rewrite gcd0p mulr0 eqpxx. have [-> | mn0] := eqVneq m 0; first by rewrite mul0r gcdp0 eqpxx. rewrite gcdpE modp_mull gcd0p size_mul //; case: leqP; last by rewrite eqpxx. rewrite (polySpred mn0) addSn /= -[leqRHS]add0n leq_add2r -ltnS. rewrite -polySpred //= leq_eqVlt ltnS size_poly_leq0 (negPf mn0) orbF. case/size_poly1P=> c cn0 -> {mn0 m}; rewrite mul_polyC. suff -> : n %% (c *: n) = 0 by rewrite gcd0p; apply: eqp_scale. by apply/modp_eq0P; rewrite dvdpZl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_mull
gcdp_mulrm n : gcdp n (n * m) %= n. Proof. by rewrite mulrC gcdp_mull. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_mulr
gcdp_scalelc m n : c != 0 -> gcdp (c *: m) n %= gcdp m n. Proof. move=> cn0; rewrite /eqp dvdp_gcd [gcdp m n %| _]dvdp_gcd !dvdp_gcdr !andbT. apply/andP; split; last first. by apply: dvdp_trans (dvdp_gcdl _ _) _; rewrite dvdpZr. by apply: dvdp_trans (dvdp_gcdl _ _) _; rewrite dvdpZl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_scalel
gcdp_scalerc m n : c != 0 -> gcdp m (c *: n) %= gcdp m n. Proof. move=> cn0; apply: eqp_trans (gcdpC _ _) _. by apply: eqp_trans (gcdp_scalel _ _ _) _ => //; apply: gcdpC. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_scaler
dvdp_gcd_idlm n : m %| n -> gcdp m n %= m. Proof. have [-> | mn0] := eqVneq m 0. by rewrite dvd0p => /eqP ->; rewrite gcdp0 eqpxx. rewrite dvdp_eq; move/eqP/(f_equal (gcdp m)) => h. apply: eqp_trans (gcdp_mull (n %/ m) _). by rewrite -h eqp_sym gcdp_scaler // expf_neq0 // lead_coef_eq0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_gcd_idl
dvdp_gcd_idrm n : n %| m -> gcdp m n %= n. Proof. by move/dvdp_gcd_idl; exact/eqp_trans/gcdpC. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_gcd_idr
gcdp_expp k l : gcdp (p ^+ k) (p ^+ l) %= p ^+ minn k l. Proof. case: leqP => [|/ltnW] /subnK <-; rewrite exprD; first exact: gcdp_mull. exact/(eqp_trans (gcdpC _ _))/gcdp_mull. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_exp
gcdp_eq0p q : gcdp p q == 0 = (p == 0) && (q == 0). Proof. apply/idP/idP; last by case/andP => /eqP -> /eqP ->; rewrite gcdp0. have h m n: gcdp m n == 0 -> (m == 0). by rewrite -(dvd0p m); move/eqP<-; rewrite dvdp_gcdl. by move=> ?; rewrite (h _ q) // (h _ p) // -eqp0 (eqp_ltrans (gcdpC _ _)) eqp0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_eq0
eqp_gcdrp q r : q %= r -> gcdp p q %= gcdp p r. Proof. move=> eqr; rewrite /eqp !(dvdp_gcd, dvdp_gcdl, andbT) /=. by rewrite -(eqp_dvdr _ eqr) dvdp_gcdr (eqp_dvdr _ eqr) dvdp_gcdr. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eqp_gcdr
eqp_gcdlr p q : p %= q -> gcdp p r %= gcdp q r. Proof. move=> eqr; rewrite /eqp !(dvdp_gcd, dvdp_gcdr, andbT) /=. by rewrite -(eqp_dvdr _ eqr) dvdp_gcdl (eqp_dvdr _ eqr) dvdp_gcdl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eqp_gcdl
eqp_gcdp1 p2 q1 q2 : p1 %= p2 -> q1 %= q2 -> gcdp p1 q1 %= gcdp p2 q2. Proof. move=> e1 e2; exact: eqp_trans (eqp_gcdr _ e2) (eqp_gcdl _ e1). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eqp_gcd
eqp_rgcd_gcdp q : rgcdp p q %= gcdp p q. Proof. move: {2}(minn (size p) (size q)) (leqnn (minn (size p) (size q))) => n. elim: n p q => [p q|n ihn p q hs]. rewrite leqn0; case: ltnP => _; rewrite size_poly_eq0; move/eqP->. by rewrite gcd0p rgcd0p eqpxx. by rewrite gcdp0 rgcdp0 eqpxx. have [-> | pn0] := eqVneq p 0; first by rewrite gcd0p rgcd0p eqpxx. have [-> | qn0] := eqVneq q 0; first by rewrite gcdp0 rgcdp0 eqpxx. rewrite gcdpE rgcdpE; case: ltnP hs => sp hs. have e := eqp_rmod_mod q p; apply/eqp_trans/ihn: (eqp_gcdl p e). by rewrite (eqp_size e) geq_min -ltnS (leq_trans _ hs) ?ltn_modp. have e := eqp_rmod_mod p q; apply/eqp_trans/ihn: (eqp_gcdl q e). by rewrite (eqp_size e) geq_min -ltnS (leq_trans _ hs) ?ltn_modp. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eqp_rgcd_gcd
gcdp_modlm n : gcdp (m %% n) n %= gcdp m n. Proof. have [/modp_small -> // | lenm] := ltnP (size m) (size n). by rewrite (gcdpE m n) ltnNge lenm. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_modl
gcdp_modrm n : gcdp m (n %% m) %= gcdp m n. Proof. apply: eqp_trans (gcdpC _ _); apply: eqp_trans (gcdp_modl _ _); exact: gcdpC. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_modr
gcdp_defd m n : d %| m -> d %| n -> (forall d', d' %| m -> d' %| n -> d' %| d) -> gcdp m n %= d. Proof. move=> dm dn h; rewrite /eqp dvdp_gcd dm dn !andbT. by apply: h; rewrite (dvdp_gcdl, dvdp_gcdr). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_def
coprimepp q := size (gcdp p q) == 1%N.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep
coprimep_size_gcdp q : coprimep p q -> size (gcdp p q) = 1. Proof. by rewrite /coprimep=> /eqP. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_size_gcd
coprimep_defp q : coprimep p q = (size (gcdp p q) == 1). Proof. done. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_def
coprimepZlc m n : c != 0 -> coprimep (c *: m) n = coprimep m n. Proof. by move=> ?; rewrite !coprimep_def (eqp_size (gcdp_scalel _ _ _)). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimepZl
coprimepZrc m n: c != 0 -> coprimep m (c *: n) = coprimep m n. Proof. by move=> ?; rewrite !coprimep_def (eqp_size (gcdp_scaler _ _ _)). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimepZr
coprimeppp : coprimep p p = (size p == 1). Proof. by rewrite coprimep_def gcdpp. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimepp
gcdp_eqp1p q : gcdp p q %= 1 = coprimep p q. Proof. by rewrite coprimep_def size_poly_eq1. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_eqp1
coprimep_symp q : coprimep p q = coprimep q p. Proof. by rewrite -!gcdp_eqp1; apply: eqp_ltrans; rewrite gcdpC. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_sym
coprime1pp : coprimep 1 p. Proof. by rewrite /coprimep -[1%N](size_poly1 R); exact/eqP/eqp_size/gcd1p. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprime1p
coprimep1p : coprimep p 1. Proof. by rewrite coprimep_sym; apply: coprime1p. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep1
coprimep0p : coprimep p 0 = (p %= 1). Proof. by rewrite /coprimep gcdp0 size_poly_eq1. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep0
coprime0pp : coprimep 0 p = (p %= 1). Proof. by rewrite coprimep_sym coprimep0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprime0p
coprimepPp q : reflect (forall d, d %| p -> d %| q -> d %= 1) (coprimep p q). Proof. rewrite /coprimep; apply: (iffP idP) => [/eqP hs d dvddp dvddq | h]. have/dvdp_eqp1: d %| gcdp p q by rewrite dvdp_gcd dvddp dvddq. by rewrite -size_poly_eq1 hs; exact. by rewrite size_poly_eq1; case/andP: (dvdp_gcdlr p q); apply: h. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimepP
coprimepPnp q : p != 0 -> reflect (exists d, (d %| gcdp p q) && ~~ (d %= 1)) (~~ coprimep p q). Proof. move=> p0; apply: (iffP idP). by rewrite -gcdp_eqp1=> ng1; exists (gcdp p q); rewrite dvdpp /=. case=> d /andP [dg]; apply: contra; rewrite -gcdp_eqp1=> g1. by move: dg; rewrite (eqp_dvdr _ g1) dvdp1 size_poly_eq1. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimepPn
coprimep_dvdlq p r : r %| q -> coprimep p q -> coprimep p r. Proof. move=> rp /coprimepP cpq'; apply/coprimepP => d dp dr. exact/cpq'/(dvdp_trans dr). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_dvdl
coprimep_dvdrp q r : r %| p -> coprimep p q -> coprimep r q. Proof. by move=> rp; rewrite ![coprimep _ q]coprimep_sym; apply/coprimep_dvdl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_dvdr
coprimep_modlp q : coprimep (p %% q) q = coprimep p q. Proof. rewrite !coprimep_def [in RHS]gcdpE. by case: ltnP => // hpq; rewrite modp_small // gcdpE hpq. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_modl
coprimep_modrq p : coprimep q (p %% q) = coprimep q p. Proof. by rewrite ![coprimep q _]coprimep_sym coprimep_modl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_modr
rcoprimep_coprimepq p : rcoprimep q p = coprimep q p. Proof. by rewrite /coprimep /rcoprimep (eqp_size (eqp_rgcd_gcd _ _)). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
rcoprimep_coprimep
eqp_coprimeprp q r : q %= r -> coprimep p q = coprimep p r. Proof. by rewrite -!gcdp_eqp1; move/(eqp_gcdr p)/eqp_ltrans. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eqp_coprimepr
eqp_coprimeplp q r : q %= r -> coprimep q p = coprimep r p. Proof. by rewrite !(coprimep_sym _ p); apply: eqp_coprimepr. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eqp_coprimepl
egcdp_recp q k {struct k} : {poly R} * {poly R} := if k is k'.+1 then if q == 0 then (1, 0) else let: (u, v) := egcdp_rec q (p %% q) k' in (lead_coef q ^+ scalp p q *: v, (u - v * (p %/ q))) else (1, 0).
Fixpoint
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
egcdp_rec
egcdpp q := if size q <= size p then egcdp_rec p q (size q) else let e := egcdp_rec q p (size p) in (e.2, e.1).
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
egcdp
egcdp0p : egcdp p 0 = (1, 0). Proof. by rewrite /egcdp size_poly0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
egcdp0
egcdp_recP: forall k p q, q != 0 -> size q <= k -> size q <= size p -> let e := (egcdp_rec p q k) in [/\ size e.1 <= size q, size e.2 <= size p & gcdp p q %= e.1 * p + e.2 * q]. Proof. elim=> [|k ihk] p q /= qn0; first by rewrite size_poly_leq0 (negPf qn0). move=> sqSn qsp; rewrite (negPf qn0). have sp : size p > 0 by apply: leq_trans qsp; rewrite size_poly_gt0. have [r0 | rn0] /= := eqVneq (p %%q) 0. rewrite r0 /egcdp_rec; case: k ihk sqSn => [|n] ihn sqSn /=. rewrite !scaler0 !mul0r subr0 add0r mul1r size_poly0 size_poly1. by rewrite dvdp_gcd_idr /dvdp ?r0. rewrite !eqxx mul0r scaler0 /= mul0r add0r subr0 mul1r size_poly0 size_poly1. by rewrite dvdp_gcd_idr /dvdp ?r0 //. have h1 : size (p %% q) <= k. by rewrite -ltnS; apply: leq_trans sqSn; rewrite ltn_modp. have h2 : size (p %% q) <= size q by rewrite ltnW // ltn_modp. have := ihk q (p %% q) rn0 h1 h2. case: (egcdp_rec _ _)=> u v /= => [[ihn'1 ihn'2 ihn'3]]. rewrite gcdpE ltnNge qsp //= (eqp_ltrans (gcdpC _ _)); split; last first. - apply: (eqp_trans ihn'3). rewrite mulrBl addrCA -scalerAl scalerAr -mulrA -mulrBr. by rewrite divp_eq addrAC subrr add0r eqpxx. - apply: (leq_trans (size_polyD _ _)). have [-> | vn0] := eqVneq v 0. rewrite mul0r size_polyN size_poly0 maxn0; apply: leq_trans ihn'1 _. exact: leq_modp. have [-> | qqn0] := eqVneq (p %/ q) 0. rewrite mulr0 size_polyN size_poly0 maxn0; apply: leq_trans ihn'1 _. exact: leq_modp. rewrite geq_max (leq_trans ihn'1) ?leq_modp //= size ...
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
egcdp_recP
egcdpPp q : p != 0 -> q != 0 -> forall (e := egcdp p q), [/\ size e.1 <= size q, size e.2 <= size p & gcdp p q %= e.1 * p + e.2 * q]. Proof. rewrite /egcdp => pn0 qn0; case: (leqP (size q) (size p)) => /= [|/ltnW] hp. exact: egcdp_recP. case: (egcdp_recP pn0 (leqnn (size p)) hp) => h1 h2 h3; split => //. by rewrite (eqp_ltrans (gcdpC _ _)) addrC. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
egcdpP
egcdpEp q (e := egcdp p q) : gcdp p q %= e.1 * p + e.2 * q. Proof. rewrite {}/e; have [-> /= | qn0] := eqVneq q 0. by rewrite gcdp0 egcdp0 mul1r mulr0 addr0. have [-> | pn0] := eqVneq p 0; last by case: (egcdpP pn0 qn0). by rewrite gcd0p /egcdp size_poly0 size_poly_leq0 (negPf qn0) /= !simp. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
egcdpE
Bezoutpp q : exists u, u.1 * p + u.2 * q %= (gcdp p q). Proof. have [-> | pn0] := eqVneq p 0. by rewrite gcd0p; exists (0, 1); rewrite mul0r mul1r add0r. have [-> | qn0] := eqVneq q 0. by rewrite gcdp0; exists (1, 0); rewrite mul0r mul1r addr0. pose e := egcdp p q; exists e; rewrite eqp_sym. by case: (egcdpP pn0 qn0). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Bezoutp
Bezout_coprimepPp q : reflect (exists u, u.1 * p + u.2 * q %= 1) (coprimep p q). Proof. rewrite -gcdp_eqp1; apply: (iffP idP)=> [g1|]. by case: (Bezoutp p q) => [[u v] Puv]; exists (u, v); apply: eqp_trans g1. case=> [[u v]]; rewrite eqp_sym=> Puv; rewrite /eqp (eqp_dvdr _ Puv). by rewrite dvdp_addr dvdp_mull ?dvdp_gcdl ?dvdp_gcdr //= dvd1p. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Bezout_coprimepP
coprimep_rootp q x : coprimep p q -> root p x -> q.[x] != 0. Proof. case/Bezout_coprimepP=> [[u v] euv] px0. move/eqpP: euv => [[c1 c2]] /andP /= [c1n0 c2n0 e]. suffices: c1 * (v.[x] * q.[x]) != 0. by rewrite !mulf_eq0 !negb_or c1n0 /=; case/andP. have := f_equal (horner^~ x) e; rewrite /= !hornerZ hornerD. by rewrite !hornerM (eqP px0) mulr0 add0r hornerC mulr1; move->. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_root
Gauss_dvdplp q d: coprimep d q -> (d %| p * q) = (d %| p). Proof. move/Bezout_coprimepP=>[[u v] Puv]; apply/idP/idP; last exact: dvdp_mulr. move/(eqp_mull p): Puv; rewrite mulr1 mulrDr eqp_sym=> peq dpq. rewrite (eqp_dvdr _ peq) dvdp_addr; first by rewrite mulrA mulrAC dvdp_mulr. by rewrite mulrA dvdp_mull ?dvdpp. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Gauss_dvdpl
Gauss_dvdprp q d: coprimep d q -> (d %| q * p) = (d %| p). Proof. by rewrite mulrC; apply: Gauss_dvdpl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Gauss_dvdpr
Gauss_dvdpm n p : coprimep m n -> (m * n %| p) = (m %| p) && (n %| p). Proof. have [-> | mn0] := eqVneq m 0. by rewrite coprime0p => /eqp_dvdl->; rewrite !mul0r dvd0p dvd1p andbT. have [-> | nn0] := eqVneq n 0. by rewrite coprimep0 => /eqp_dvdl->; rewrite !mulr0 dvd1p. move=> hc; apply/idP/idP => [mnmp | /andP [dmp dnp]]. move/Gauss_dvdpl: hc => <-; move: (dvdp_mull m mnmp); rewrite dvdp_mul2l //. move->; move: (dvdp_mulr n mnmp); rewrite dvdp_mul2r // andbT. exact: dvdp_mulr. move: (dnp); rewrite dvdp_eq. set c2 := _ ^+ _; set q2 := _ %/ _; move/eqP=> e2. have/esym := Gauss_dvdpl q2 hc; rewrite -e2. have -> : m %| c2 *: p by rewrite -mul_polyC dvdp_mull. rewrite dvdp_eq; set c3 := _ ^+ _; set q3 := _ %/ _; move/eqP=> e3. apply: (@eq_dvdp (c3 * c2) q3). by rewrite mulf_neq0 // expf_neq0 // lead_coef_eq0. by rewrite mulrA -e3 -scalerAl -e2 scalerA. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Gauss_dvdp
Gauss_gcdprp m n : coprimep p m -> gcdp p (m * n) %= gcdp p n. Proof. move=> co_pm; apply/eqP; rewrite /eqp !dvdp_gcd !dvdp_gcdl /= andbC. rewrite dvdp_mull ?dvdp_gcdr // -(@Gauss_dvdpl _ m). by rewrite mulrC dvdp_gcdr. apply/coprimepP=> d; rewrite dvdp_gcd; case/andP=> hdp _ hdm. by move/coprimepP: co_pm; apply. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Gauss_gcdpr
Gauss_gcdplp m n : coprimep p n -> gcdp p (m * n) %= gcdp p m. Proof. by move=> co_pn; rewrite mulrC Gauss_gcdpr. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Gauss_gcdpl
coprimepMrp q r : coprimep p (q * r) = (coprimep p q && coprimep p r). Proof. apply/coprimepP/andP=> [hp | [/coprimepP-hq hr]]. by split; apply/coprimepP=> d dp dq; rewrite hp //; [apply/dvdp_mulr | apply/dvdp_mull]. move=> d dp dqr; move/(_ _ dp) in hq. rewrite Gauss_dvdpl in dqr; first exact: hq. by move/coprimep_dvdr: hr; apply. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimepMr
coprimepMlp q r: coprimep (q * r) p = (coprimep q p && coprimep r p). Proof. by rewrite ![coprimep _ p]coprimep_sym coprimepMr. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimepMl
modp_coprimek u n : k != 0 -> (k * u) %% n %= 1 -> coprimep k n. Proof. move=> kn0 hmod; apply/Bezout_coprimepP. exists (((lead_coef n)^+(scalp (k * u) n) *: u), (- (k * u %/ n))). rewrite -scalerAl mulrC (divp_eq (u * k) n) mulNr -addrAC subrr add0r. by rewrite mulrC. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
modp_coprime
coprimep_pexplk m n : 0 < k -> coprimep (m ^+ k) n = coprimep m n. Proof. case: k => // k _; elim: k => [|k IHk]; first by rewrite expr1. by rewrite exprS coprimepMl -IHk andbb. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_pexpl
coprimep_pexprk m n : 0 < k -> coprimep m (n ^+ k) = coprimep m n. Proof. by move=> k_gt0; rewrite !(coprimep_sym m) coprimep_pexpl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_pexpr
coprimep_explk m n : coprimep m n -> coprimep (m ^+ k) n. Proof. by case: k => [|k] co_pm; rewrite ?coprime1p // coprimep_pexpl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_expl
coprimep_exprk m n : coprimep m n -> coprimep m (n ^+ k). Proof. by rewrite !(coprimep_sym m); apply: coprimep_expl. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_expr
gcdp_mul2lp q r : gcdp (p * q) (p * r) %= (p * gcdp q r). Proof. have [->|hp] := eqVneq p 0; first by rewrite !mul0r gcdp0 eqpxx. rewrite /eqp !dvdp_gcd !dvdp_mul2l // dvdp_gcdr dvdp_gcdl !andbT. move: (Bezoutp q r) => [[u v]] huv. rewrite eqp_sym in huv; rewrite (eqp_dvdr _ (eqp_mull _ huv)). rewrite mulrDr ![p * (_ * _)]mulrCA. by apply: dvdp_add; rewrite dvdp_mull// (dvdp_gcdr, dvdp_gcdl). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_mul2l
gcdp_mul2rq r p : gcdp (q * p) (r * p) %= gcdp q r * p. Proof. by rewrite ![_ * p]mulrC gcdp_mul2l. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gcdp_mul2r
mulp_gcdrp q r : r * (gcdp p q) %= gcdp (r * p) (r * q). Proof. by rewrite eqp_sym gcdp_mul2l. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
mulp_gcdr
mulp_gcdlp q r : (gcdp p q) * r %= gcdp (p * r) (q * r). Proof. by rewrite eqp_sym gcdp_mul2r. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
mulp_gcdl
coprimep_div_gcdp q : (p != 0) || (q != 0) -> coprimep (p %/ (gcdp p q)) (q %/ gcdp p q). Proof. rewrite -negb_and -gcdp_eq0 -gcdp_eqp1 => gpq0. rewrite -(@eqp_mul2r (gcdp p q)) // mul1r (eqp_ltrans (mulp_gcdl _ _ _)). have: gcdp p q %| p by rewrite dvdp_gcdl. have: gcdp p q %| q by rewrite dvdp_gcdr. rewrite !dvdp_eq => /eqP <- /eqP <-. have lcn0 k : (lead_coef (gcdp p q)) ^+ k != 0. by rewrite expf_neq0 ?lead_coef_eq0. by apply: eqp_gcd; rewrite ?eqp_scale. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_div_gcd
divp_eq0p q : (p %/ q == 0) = [|| p == 0, q ==0 | size p < size q]. Proof. apply/eqP/idP=> [d0|]; last first. case/or3P; [by move/eqP->; rewrite div0p| by move/eqP->; rewrite divp0|]. by move/divp_small. case: eqVneq => // _; case: eqVneq => // qn0. move: (divp_eq p q); rewrite d0 mul0r add0r. move/(f_equal (fun x : {poly R} => size x)). by rewrite size_scale ?lc_expn_scalp_neq0 // => ->; rewrite ltn_modp qn0 !orbT. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
divp_eq0
dvdp_div_eq0p q : q %| p -> (p %/ q == 0) = (p == 0). Proof. move=> dvdp_qp; have [->|p_neq0] := eqVneq p 0; first by rewrite div0p eqxx. rewrite divp_eq0 ltnNge dvdp_leq // (negPf p_neq0) orbF /=. by apply: contraTF dvdp_qp=> /eqP ->; rewrite dvd0p. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_div_eq0
Bezout_coprimepPnp q : p != 0 -> q != 0 -> reflect (exists2 uv : {poly R} * {poly R}, (0 < size uv.1 < size q) && (0 < size uv.2 < size p) & uv.1 * p = uv.2 * q) (~~ (coprimep p q)). Proof. move=> pn0 qn0; apply: (iffP idP); last first. case=> [[u v] /= /andP [/andP [ps1 s1] /andP [ps2 s2]] e]. have: ~~(size (q * p) <= size (u * p)). rewrite -ltnNge !size_mul // -?size_poly_gt0 // (polySpred pn0) !addnS. by rewrite ltn_add2r. apply: contra => ?; apply: dvdp_leq; rewrite ?mulf_neq0 // -?size_poly_gt0 //. by rewrite mulrC Gauss_dvdp // dvdp_mull // e dvdp_mull. rewrite coprimep_def neq_ltn ltnS size_poly_leq0 gcdp_eq0. rewrite (negPf pn0) (negPf qn0) /=. case sg: (size (gcdp p q)) => [|n] //; case: n sg=> [|n] // sg _. move: (dvdp_gcdl p q); rewrite dvdp_eq; set c1 := _ ^+ _; move/eqP=> hu1. move: (dvdp_gcdr p q); rewrite dvdp_eq; set c2 := _ ^+ _; move/eqP=> hv1. exists (c1 *: (q %/ gcdp p q), c2 *: (p %/ gcdp p q)); last first. by rewrite -!scalerAl !scalerAr hu1 hv1 mulrCA. rewrite !size_scale ?lc_expn_scalp_neq0 //= !size_poly_gt0 !divp_eq0. rewrite gcdp_eq0 !(negPf pn0) !(negPf qn0) /= -!leqNgt leq_gcdpl //. rewrite leq_gcdpr //= !ltn_divpl -?size_poly_eq0 ?sg //. rewrite !size_mul // -?size_poly_eq0 ?sg // ![(_ + n.+2)%N]addnS /=. by rewrite -!(addn1 (size _)) !leq_add2l. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
Bezout_coprimepPn
dvdp_pexp2rm n k : k > 0 -> (m ^+ k %| n ^+ k) = (m %| n). Proof. move=> k_gt0; apply/idP/idP; last exact: dvdp_exp2r. have [-> // | nn0] := eqVneq n 0; have [-> | mn0] := eqVneq m 0. move/prednK: k_gt0=> {1}<-; rewrite exprS mul0r //= !dvd0p expf_eq0. by case/andP=> _ ->. set d := gcdp m n; have := dvdp_gcdr m n; rewrite -/d dvdp_eq. set c1 := _ ^+ _; set n' := _ %/ _; move/eqP=> def_n. have := dvdp_gcdl m n; rewrite -/d dvdp_eq. set c2 := _ ^+ _; set m' := _ %/ _; move/eqP=> def_m. have dn0 : d != 0 by rewrite gcdp_eq0 negb_and nn0 orbT. have c1n0 : c1 != 0 by rewrite !expf_neq0 // lead_coef_eq0. have c2n0 : c2 != 0 by rewrite !expf_neq0 // lead_coef_eq0. have c2k_n0 : c2 ^+ k != 0 by rewrite !expf_neq0 // lead_coef_eq0. rewrite -(@dvdpZr (c1 ^+ k)) ?expf_neq0 ?lead_coef_eq0 //. rewrite -(@dvdpZl (c2 ^+ k)) // -!exprZn def_m def_n !exprMn. rewrite dvdp_mul2r ?expf_neq0 //. have: coprimep (m' ^+ k) (n' ^+ k). by rewrite coprimep_pexpl // coprimep_pexpr // coprimep_div_gcd ?mn0. move/coprimepP=> hc hd. have /size_poly1P [c cn0 em'] : size m' == 1. case: (eqVneq m' 0) def_m => [-> /eqP | m'_n0 def_m]. by rewrite mul0r scale_poly_eq0 (negPf mn0) (negPf c2n0). have := hc _ (dvdpp _) hd; rewrite -size_poly_eq1. rewrite polySpred; last by rewrite expf_eq0 negb_and m'_n0 orbT. by rewrite size_exp eqSS muln_eq0 orbC eqn0Ngt k_gt0 /= -eqSS -polySpred. rewrite -(@dvdpZl c2) // def_m em' mul_polyC dvdpZl //. by rewrite -(@dvdpZr c1) // def_n dvdp_mull. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_pexp2r
root_gcdp q x : root (gcdp p q) x = root p x && root q x. Proof. rewrite /= !root_factor_theorem; apply/idP/andP=> [dg| [dp dq]]. by split; apply: dvdp_trans dg _; rewrite ?(dvdp_gcdl, dvdp_gcdr). have:= Bezoutp p q => [[[u v]]]; rewrite eqp_sym=> e. by rewrite (eqp_dvdr _ e) dvdp_addl dvdp_mull. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
root_gcd
root_biggcdx (ps : seq {poly R}) : root (\big[gcdp/0]_(p <- ps) p) x = all (fun p => root p x) ps. Proof. elim: ps => [|p ps ihp]; first by rewrite big_nil root0. by rewrite big_cons /= root_gcd ihp. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
root_biggcd
gdcop_recq p k := if k is m.+1 then if coprimep p q then p else gdcop_rec q (divp p (gcdp p q)) m else (q == 0)%:R.
Fixpoint
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gdcop_rec
gdcopq p := gdcop_rec q p (size p).
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gdcop
gdcop_specq p : {poly R} -> Type := GdcopSpec r of (dvdp r p) & ((coprimep r q) || (p == 0)) & (forall d, dvdp d p -> coprimep d q -> dvdp d r) : gdcop_spec q p r.
Variant
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gdcop_spec
gdcop0q : gdcop q 0 = (q == 0)%:R. Proof. by rewrite /gdcop size_poly0. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gdcop0
gdcop_recPq p k : size p <= k -> gdcop_spec q p (gdcop_rec q p k). Proof. elim: k p => [p | k ihk p] /=. move/size_poly_leq0P->. have [->|q0] := eqVneq; split; rewrite ?coprime1p // ?eqxx ?orbT //. by move=> d _; rewrite coprimep0 dvdp1 size_poly_eq1. move=> hs; case cop : (coprimep _ _); first by split; rewrite ?dvdpp ?cop. have [-> | p0] := eqVneq p 0. by rewrite div0p; apply: ihk; rewrite size_poly0 leq0n. have [-> | q0] := eqVneq q 0. rewrite gcdp0 divpp ?p0 //= => {hs ihk}; case: k=> /=. rewrite eqxx; split; rewrite ?dvd1p ?coprimep0 ?eqpxx //=. by move=> d _; rewrite coprimep0 dvdp1 size_poly_eq1. move=> n; rewrite coprimep0 polyC_eqp1 //; rewrite lc_expn_scalp_neq0. split; first by rewrite (@eqp_dvdl 1) ?dvd1p // polyC_eqp1 lc_expn_scalp_neq0. by rewrite coprimep0 polyC_eqp1 // ?lc_expn_scalp_neq0. by move=> d _; rewrite coprimep0; move/eqp_dvdl->; rewrite dvd1p. move: (dvdp_gcdl p q); rewrite dvdp_eq; move/eqP=> e. have sgp : size (gcdp p q) <= size p. by apply: dvdp_leq; rewrite ?gcdp_eq0 ?p0 ?q0 // dvdp_gcdl. have : p %/ gcdp p q != 0; last move/negPf=>p'n0. apply: dvdpN0 (dvdp_mulIl (p %/ gcdp p q) (gcdp p q)) _. by rewrite -e scale_poly_eq0 negb_or lc_expn_scalp_neq0. have gn0 : gcdp p q != 0. apply: dvdpN0 (dvdp_mulIr (p %/ gcdp p q) (gcdp p q)) _. by rewrite -e scale_poly_eq0 negb_or lc_expn_scalp_neq0. have sp' : size (p %/ (gcdp p q)) <= k. rewrite size_divp ?sgp // leq_subLR (leq_trans hs) // -add1n leq_add2r -subn1. by rewrite ...
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gdcop_recP
gdcopPq p : gdcop_spec q p (gdcop q p). Proof. by rewrite /gdcop; apply: gdcop_recP. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
gdcopP
coprimep_gdcop q : (q != 0)%B -> coprimep (gdcop p q) p. Proof. by move=> q_neq0; case: gdcopP=> d; rewrite (negPf q_neq0) orbF. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
coprimep_gdco
size2_dvdp_gdcop q d : p != 0 -> size d = 2 -> (d %| (gdcop q p)) = (d %| p) && ~~(d %| q). Proof. have [-> | dn0] := eqVneq d 0; first by rewrite size_poly0. move=> p0 sd; apply/idP/idP. case: gdcopP=> r rp crq maxr dr; move/negPf: (p0)=> p0f. rewrite (dvdp_trans dr) //=. apply: contraL crq => dq; rewrite p0f orbF; apply/coprimepPn. by apply: contraNneq p0 => r0; move: rp; rewrite r0 dvd0p. by exists d; rewrite dvdp_gcd dr dq -size_poly_eq1 sd. case/andP=> dp dq; case: gdcopP=> r rp crq maxr; apply: maxr=> //. apply/coprimepP=> x xd xq. move: (dvdp_leq dn0 xd); rewrite leq_eqVlt sd; case/orP; last first. rewrite ltnS leq_eqVlt ltnS size_poly_leq0 orbC. case/predU1P => [x0|]; last by rewrite -size_poly_eq1. by move: xd; rewrite x0 dvd0p (negPf dn0). by rewrite -sd dvdp_size_eqp //; move/(eqp_dvdl q); rewrite xq (negPf dq). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
size2_dvdp_gdco
dvdp_gdcop q : (gdcop p q) %| q. Proof. by case: gdcopP. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_gdco
root_gdcop q x : p != 0 -> root (gdcop q p) x = root p x && ~~(root q x). Proof. move=> p0 /=; rewrite !root_factor_theorem. apply: size2_dvdp_gdco; rewrite ?p0 //. by rewrite size_polyDl size_polyX // size_polyN size_polyC ltnS; case: (x != 0). Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
root_gdco
dvdp_comp_polyr p q : (p %| q) -> (p \Po r) %| (q \Po r). Proof. have [-> | pn0] := eqVneq p 0. by rewrite comp_poly0 !dvd0p; move/eqP->; rewrite comp_poly0. rewrite dvdp_eq; set c := _ ^+ _; set s := _ %/ _; move/eqP=> Hq. apply: (@eq_dvdp c (s \Po r)); first by rewrite expf_neq0 // lead_coef_eq0. by rewrite -comp_polyZ Hq comp_polyM. Qed.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp_comp_poly