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rmodp0p : rmodp p 0 = p. Proof. by rewrite /rmodp unlock 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
rmodp0
rscalp_smallp q : size p < size q -> rscalp p q = 0. Proof. rewrite /rscalp unlock; case: eqP => _ // spq. by case sp: (size p) => [| s] /=; rewrite spq. 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
rscalp_small
ltn_rmodpp q : (size (rmodp p q) < size q) = (q != 0). Proof. rewrite /rdivp /rmodp /rscalp unlock; have [->|q0] := eqVneq q 0. by rewrite /= size_poly0 ltn0. elim: (size p) 0%N 0 {1 3}p (leqnn (size p)) => [|n ihn] k q1 r. move/size_poly_leq0P->. by rewrite /= size_poly0 size_poly_gt0 q0 size_poly0 size_poly_gt0. move=> hr /=; case: (ltnP (size r)) => // hsrq; apply/ihn/leq_sizeP => j hnj. rewrite coefB -scalerAl !coefZ coefXnM coefMC ltn_subRL ltnNge. have sq: 0 < size q by rewrite size_poly_gt0. have sr: 0 < size r by apply: leq_trans hsrq. have hj: (size r).-1 <= j by apply: leq_trans hnj; rewrite -ltnS prednK. move: (leq_add sq hj); rewrite add1n prednK // => -> /=. move: hj; rewrite leq_eqVlt prednK // => /predU1P [<- | hj]. by rewrite -predn_sub subKn // !lead_coefE subrr. have/leq_sizeP -> //: size q <= j - (size r - size q). by rewrite subnBA // leq_subRL ?leq_add2r // (leq_trans hj) // leq_addr. by move/leq_sizeP: hj => -> //; rewrite mul0r mulr0 subr0. 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
ltn_rmodp
ltn_rmodpN0p q : q != 0 -> size (rmodp p q) < size q. Proof. by rewrite ltn_rmodp. 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
ltn_rmodpN0
rmodp1p : rmodp p 1 = 0. Proof. apply/eqP; have := ltn_rmodp p 1. by rewrite !oner_neq0 -size_poly_eq0 size_poly1 ltnS leqn0. 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
rmodp1
rmodp_smallp q : size p < size q -> rmodp p q = p. Proof. rewrite /rmodp unlock; have [->|_] := eqP; first by rewrite size_poly0. by case sp: (size p) => [| s] Hs /=; rewrite sp Hs /=. 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
rmodp_small
leq_rmodpm d : size (rmodp m d) <= size m. Proof. have [/rmodp_small -> //|h] := ltnP (size m) (size d). have [->|d0] := eqVneq d 0; first by rewrite rmodp0. by apply: leq_trans h; apply: ltnW; rewrite ltn_rmodp. 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_rmodp
rmodpCp c : c != 0 -> rmodp p c%:P = 0. Proof. move=> Hc; apply/eqP; rewrite -size_poly_leq0 -ltnS. have -> : 1%N = nat_of_bool (c != 0) by rewrite Hc. by rewrite -size_polyC ltn_rmodp polyC_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
rmodpC
rdvdp0d : rdvdp d 0. Proof. by rewrite /rdvdp rmod0p. 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
rdvdp0
rdvd0pn : rdvdp 0 n = (n == 0). Proof. by rewrite /rdvdp rmodp0. 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
rdvd0p
rdvd0pPn : reflect (n = 0) (rdvdp 0 n). Proof. by apply: (iffP idP); rewrite rdvd0p; move/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
rdvd0pP
rdvdpN0p q : rdvdp p q -> q != 0 -> p != 0. Proof. by move=> pq hq; apply: contraTneq pq => ->; rewrite rdvd0p. 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
rdvdpN0
rdvdp1d : rdvdp d 1 = (size d == 1). Proof. rewrite /rdvdp; have [->|] := eqVneq d 0. by rewrite rmodp0 size_poly0 (negPf (oner_neq0 _)). rewrite -size_poly_leq0 -ltnS; case: ltngtP => // [|/eqP] hd _. by rewrite rmodp_small ?size_poly1 // oner_eq0. have [c cn0 ->] := size_poly1P _ hd. rewrite /rmodp unlock -size_poly_eq0 size_poly1 /= size_poly1 size_polyC cn0 /=. by rewrite polyC_eq0 (negPf cn0) !lead_coefC !scale1r subrr !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
rdvdp1
rdvd1pm : rdvdp 1 m. Proof. by rewrite /rdvdp rmodp1. 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
rdvd1p
Nrdvdp_small(n d : {poly R}) : n != 0 -> size n < size d -> rdvdp d n = false. Proof. by move=> nn0 hs; rewrite /rdvdp (rmodp_small hs); apply: negPf. 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
Nrdvdp_small
rmodp_eq0Pp q : reflect (rmodp p q = 0) (rdvdp q p). Proof. exact: (iffP 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
rmodp_eq0P
rmodp_eq0p q : rdvdp q p -> rmodp p q = 0. Proof. exact: rmodp_eq0P. 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
rmodp_eq0
rdvdp_leqp q : rdvdp p q -> q != 0 -> size p <= size q. Proof. by move=> dvd_pq; rewrite leqNgt; apply: contra => /rmodp_small <-. 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
rdvdp_leq
rgcdpp 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 := rmodp 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.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
rgcdp
rgcd0p: left_id 0 rgcdp. Proof. move=> p; rewrite /rgcdp size_poly0 size_poly_gt0 if_neg. case: ifP => /= [_ | nzp]; first by rewrite eqxx. by rewrite polySpred !(rmodp0, nzp) //; case: _.-1 => [|m]; rewrite rmod0p 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
rgcd0p
rgcdp0: right_id 0 rgcdp. Proof. move=> p; have:= rgcd0p p; rewrite /rgcdp size_poly0 size_poly_gt0. by case: eqVneq => p0; rewrite ?(eqxx, p0) //= 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
rgcdp0
rgcdpEp q : rgcdp p q = if size p < size q then rgcdp (rmodp q p) p else rgcdp (rmodp p q) q. Proof. pose rgcdp_rec := fix rgcdp_rec (n : nat) (pp qq : {poly R}) {struct n} := let rr := rmodp pp qq in if rr == 0 then qq else if n is n1.+1 then rgcdp_rec n1 qq rr else rr. have Irec: forall m n p q, size q <= m -> size q <= n -> size q < size p -> rgcdp_rec m p q = rgcdp_rec n p q. + elim=> [|m Hrec] [|n] //= p1 q1. - move/size_poly_leq0P=> -> _; rewrite size_poly0 size_poly_gt0 rmodp0. by move/negPf->; case: n => [|n] /=; rewrite rmod0p eqxx. - move=> _ /size_poly_leq0P ->; rewrite size_poly0 size_poly_gt0 rmodp0. by move/negPf->; case: m {Hrec} => [|m] /=; rewrite rmod0p eqxx. case: eqVneq => Epq Sm Sn Sq //; have [->|nzq] := eqVneq q1 0. by case: n m {Sm Sn Hrec} => [|m] [|n] //=; rewrite rmod0p eqxx. apply: Hrec; last by rewrite ltn_rmodp. by rewrite -ltnS (leq_trans _ Sm) // ltn_rmodp. by rewrite -ltnS (leq_trans _ Sn) // ltn_rmodp. have [->|nzp] := eqVneq p 0. by rewrite rmod0p rmodp0 rgcd0p rgcdp0 if_same. have [->|nzq] := eqVneq q 0. by rewrite rmod0p rmodp0 rgcd0p rgcdp0 if_same. rewrite /rgcdp -/rgcdp_rec !ltn_rmodp (negPf nzp) (negPf nzq) /=. have [ltpq|leqp] := ltnP; rewrite !(negPf nzp, negPf nzq) //= polySpred //=. have [->|nzqp] := eqVneq. by case: (size p) => [|[|s]]; rewrite /= rmodp0 (negPf nzp) // rmod0p eqxx. apply: Irec => //; last by rewrite ltn_rmodp. by rewrite -ltnS -polySpred // (leq_tr ...
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
rgcdpE
comm_redivp_specm d : nat * {poly R} * {poly R} -> Type := ComEdivnSpec k (q r : {poly R}) of (GRing.comm d (lead_coef d)%:P -> m * (lead_coef d ^+ k)%:P = q * d + r) & (d != 0 -> size r < size d) : comm_redivp_spec m d (k, q, 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
comm_redivp_spec
comm_redivpPm d : comm_redivp_spec m d (redivp m d). Proof. rewrite unlock; have [->|Hd] := eqVneq d 0. by constructor; rewrite !(simp, eqxx). have: GRing.comm d (lead_coef d)%:P -> m * (lead_coef d ^+ 0)%:P = 0 * d + m. by rewrite !simp. elim: (size m) 0%N 0 {1 4 6}m (leqnn (size m)) => [|n IHn] k q r Hr /=. move/size_poly_leq0P: Hr ->. suff hsd: size (0: {poly R}) < size d by rewrite hsd => /= ?; constructor. by rewrite size_poly0 size_poly_gt0. case: ltnP => Hlt Heq; first by constructor. apply/IHn=> [|Cda]; last first. rewrite mulrDl addrAC -addrA subrK exprSr polyCM mulrA Heq //. by rewrite mulrDl -mulrA Cda mulrA. apply/leq_sizeP => j Hj; rewrite coefB coefMC -scalerAl coefZ coefXnM. rewrite ltn_subRL ltnNge (leq_trans Hr) /=; last first. by apply: leq_ltn_trans Hj _; rewrite -add1n leq_add2r size_poly_gt0. move: Hj; rewrite leq_eqVlt; case/predU1P => [<-{j} | Hj]; last first. rewrite !nth_default ?simp ?oppr0 ?(leq_trans Hr) //. by rewrite -{1}(subKn Hlt) leq_sub2r // (leq_trans Hr). move: Hr; rewrite leq_eqVlt ltnS; case/predU1P=> Hqq; last first. by rewrite !nth_default ?simp ?oppr0 // -{1}(subKn Hlt) leq_sub2r. rewrite /lead_coef Hqq polySpred // subSS subKn ?addrN //. by rewrite -subn1 leq_subLR add1n -Hqq. 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
comm_redivpP
rmodppp : GRing.comm p (lead_coef p)%:P -> rmodp p p = 0. Proof. move=> hC; rewrite /rmodp unlock; have [-> //|] := eqVneq. rewrite -size_poly_eq0 /redivp_rec; case sp: (size p)=> [|n] // _. rewrite sp ltnn subnn expr0 hC alg_polyC !simp subrr. by case: n sp => [|n] sp; rewrite size_polyC /= 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
rmodpp
rcoprimep(p q : {poly R}) := size (rgcdp p q) == 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
rcoprimep
rgdcop_recq p n := if n is m.+1 then if rcoprimep p q then p else rgdcop_rec q (rdivp p (rgcdp 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
rgdcop_rec
rgdcopq p := rgdcop_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
rgdcop
rgdcop0q : rgdcop q 0 = (q == 0)%:R. Proof. by rewrite /rgdcop 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
rgdcop0
redivp_eqq r : size r < size d -> let k := (redivp (q * d + r) d).1.1 in let c := (lead_coef d ^+ k)%:P in redivp (q * d + r) d = (k, q * c, r * c). Proof. move=> lt_rd; case: comm_redivpP=> k q1 r1 /(_ Cdl) Heq. have dn0: d != 0 by case: (size d) lt_rd (size_poly_eq0 d) => // n _ <-. move=> /(_ dn0) Hs. have eC : q * d * (lead_coef d ^+ k)%:P = q * (lead_coef d ^+ k)%:P * d. by rewrite -mulrA polyC_exp (commrX k Cdl) mulrA. suff e1 : q1 = q * (lead_coef d ^+ k)%:P. congr (_, _, _) => //=; move/eqP: Heq. by rewrite [_ + r1]addrC -subr_eq e1 mulrDl addrAC eC subrr add0r; move/eqP. have : (q1 - q * (lead_coef d ^+ k)%:P) * d = r * (lead_coef d ^+ k)%:P - r1. apply: (@addIr _ r1); rewrite subrK. apply: (@addrI _ ((q * (lead_coef d ^+ k)%:P) * d)). by rewrite mulrDl mulNr !addrA [_ + (q1 * d)]addrC addrK -eC -mulrDl. move/eqP; rewrite -[_ == _ - _]subr_eq0 rreg_div0 //. by case/andP; rewrite subr_eq0; move/eqP. rewrite size_polyN; apply: (leq_ltn_trans (size_polyD _ _)); rewrite size_polyN. rewrite gtn_max Hs (leq_ltn_trans (size_polyMleq _ _)) //. rewrite size_polyC; case: (_ == _); last by rewrite addnS addn0. by rewrite addn0; apply: leq_ltn_trans lt_rd; case: size. 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
redivp_eq
rdivp_eqp : p * (lead_coef d ^+ (rscalp p d))%:P = (rdivp p d) * d + (rmodp p d). Proof. by rewrite /rdivp /rmodp /rscalp; case: comm_redivpP=> k q1 r1 Hc _; apply: Hc. 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
rdivp_eq
eq_rdvdpk q1 p: p * ((lead_coef d)^+ k)%:P = q1 * d -> rdvdp d p. Proof. move=> he. have Hnq0 := rreg_lead0 Rreg; set lq := lead_coef d. pose v := rscalp p d; pose m := maxn v k. rewrite /rdvdp -(rreg_polyMC_eq0 _ (@rregX _ _ (m - v) Rreg)). suff: ((rdivp p d) * (lq ^+ (m - v))%:P - q1 * (lq ^+ (m - k))%:P) * d + (rmodp p d) * (lq ^+ (m - v))%:P == 0. rewrite rreg_div0 //; first by case/andP. by rewrite rreg_size ?ltn_rmodp //; exact: rregX. rewrite mulrDl addrAC mulNr -!mulrA polyC_exp -(commrX (m-v) Cdl). rewrite -polyC_exp mulrA -mulrDl -rdivp_eq // [(_ ^+ (m - k))%:P]polyC_exp. rewrite -(commrX (m-k) Cdl) -polyC_exp mulrA -he -!mulrA -!polyCM -/v. by rewrite -!exprD addnC subnK ?leq_maxl // addnC subnK ?subrr ?leq_maxr. 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
eq_rdvdp
rdvdp_specp q : {poly R} -> bool -> Type := | Rdvdp k q1 & p * ((lead_coef q)^+ k)%:P = q1 * q : rdvdp_spec p q 0 true | RdvdpN & rmodp p q != 0 : rdvdp_spec p q (rmodp p q) false.
Variant
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
rdvdp_spec
rdvdp_eqPp : rdvdp_spec p d (rmodp p d) (rdvdp d p). Proof. case hdvd: (rdvdp d p); last by apply: RdvdpN; move/rmodp_eq0P/eqP: hdvd. move/rmodp_eq0P: (hdvd)->; apply: (@Rdvdp _ _ (rscalp p d) (rdivp p d)). by rewrite rdivp_eq //; move/rmodp_eq0P: (hdvd)->; rewrite addr0. 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
rdvdp_eqP
rdvdp_mullp : rdvdp d (p * d). Proof. by apply: (@eq_rdvdp 0 p); rewrite expr0 mulr1. 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
rdvdp_mull
rmodp_mullp : rmodp (p * d) d = 0. Proof. exact/eqP/rdvdp_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
rmodp_mull
rmodpp: rmodp d d = 0. Proof. by rewrite -[d in rmodp d _]mul1r rmodp_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
rmodpp
rdivpp: rdivp d d = (lead_coef d ^+ rscalp d d)%:P. Proof. have dn0 : d != 0 by rewrite -lead_coef_eq0 rreg_neq0. move: (rdivp_eq d); rewrite rmodpp addr0. suff ->: GRing.comm d (lead_coef d ^+ rscalp d d)%:P by move/(rreg_lead Rreg)->. by rewrite polyC_exp; apply: commrX. 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
rdivpp
rdvdpp: rdvdp d d. Proof. exact/eqP/rmodpp. 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
rdvdpp
rdivpKp : rdvdp d p -> rdivp p d * d = p * (lead_coef d ^+ rscalp p d)%:P. Proof. by rewrite rdivp_eq /rdvdp; move/eqP->; rewrite addr0. 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
rdivpK
redivp_eqq r : size r < size d -> let k := (redivp (q * d + r) d).1.1 in redivp (q * d + r) d = (k, q, r). Proof. case: (monic_comreg mond)=> Hc Hr /(redivp_eq Hc Hr q). by rewrite (eqP mond) => -> /=; rewrite expr1n !mulr1. 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
redivp_eq
rdivp_eqp : p = rdivp p d * d + rmodp p d. Proof. rewrite -rdivp_eq (eqP mond); last exact: commr1. by rewrite expr1n mulr1. 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
rdivp_eq
rdivpp: rdivp d d = 1. Proof. by case: (monic_comreg mond) => hc hr; rewrite rdivpp // (eqP mond) expr1n. 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
rdivpp
rdivp_addl_mul_smallq r : size r < size d -> rdivp (q * d + r) d = q. Proof. by move=> Hd; case: (monic_comreg mond)=> Hc Hr; rewrite /rdivp redivp_eq. 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
rdivp_addl_mul_small
rdivp_addl_mulq r : rdivp (q * d + r) d = q + rdivp r d. Proof. case: (monic_comreg mond)=> Hc Hr; rewrite [r in _ * _ + r]rdivp_eq addrA. by rewrite -mulrDl rdivp_addl_mul_small // ltn_rmodp monic_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
rdivp_addl_mul
rdivpDlq r : rdvdp d q -> rdivp (q + r) d = rdivp q d + rdivp r d. Proof. case: (monic_comreg mond)=> Hc Hr; rewrite [r in q + r]rdivp_eq addrA. rewrite [q in q + _ + _]rdivp_eq; move/rmodp_eq0P->. by rewrite addr0 -mulrDl rdivp_addl_mul_small // ltn_rmodp monic_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
rdivpDl
rdivpDrq r : rdvdp d r -> rdivp (q + r) d = rdivp q d + rdivp r d. Proof. by rewrite addrC; move/rdivpDl->; rewrite 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
rdivpDr
rdivp_mullp : rdivp (p * d) d = p. Proof. by rewrite -[p * d]addr0 rdivp_addl_mul rdiv0p addr0. 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
rdivp_mull
rmodp_mullp : rmodp (p * d) d = 0. Proof. by apply: rmodp_mull; rewrite (eqP mond); [apply: commr1 | apply: rreg1]. 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
rmodp_mull
rmodpp: rmodp d d = 0. Proof. by apply: rmodpp; rewrite (eqP mond); [apply: commr1 | apply: rreg1]. 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
rmodpp
rmodp_addl_mul_smallq r : size r < size d -> rmodp (q * d + r) d = r. Proof. by move=> Hd; case: (monic_comreg mond)=> Hc Hr; rewrite /rmodp redivp_eq. 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
rmodp_addl_mul_small
rmodp_id(p : {poly R}) : rmodp (rmodp p d) d = rmodp p d. Proof. by rewrite rmodp_small // ltn_rmodpN0 // monic_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
rmodp_id
rmodpDp q : rmodp (p + q) d = rmodp p d + rmodp q d. Proof. rewrite [p in LHS]rdivp_eq [q in LHS]rdivp_eq addrACA -mulrDl. rewrite rmodp_addl_mul_small //; apply: (leq_ltn_trans (size_polyD _ _)). by rewrite gtn_max !ltn_rmodp // monic_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
rmodpD
rmodpNp : rmodp (- p) d = - (rmodp p d). Proof. rewrite {1}(rdivp_eq p) opprD // -mulNr rmodp_addl_mul_small //. by rewrite size_polyN ltn_rmodp // monic_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
rmodpN
rmodpBp q : rmodp (p - q) d = rmodp p d - rmodp q d. Proof. by rewrite rmodpD rmodpN. 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
rmodpB
rmodpZa p : rmodp (a *: p) d = a *: (rmodp p d). Proof. case: (altP (a =P 0%R)) => [-> | cn0]; first by rewrite !scale0r rmod0p. have -> : ((a *: p) = (a *: (rdivp p d)) * d + a *: (rmodp p d))%R. by rewrite -scalerAl -scalerDr -rdivp_eq. rewrite rmodp_addl_mul_small //. rewrite -mul_polyC; apply: leq_ltn_trans (size_polyMleq _ _) _. rewrite size_polyC cn0 addSn add0n /= ltn_rmodp. exact: monic_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
rmodpZ
rmodp_sum(I : Type) (r : seq I) (P : pred I) (F : I -> {poly R}) : rmodp (\sum_(i <- r | P i) F i) d = (\sum_(i <- r | P i) (rmodp (F i) d)). Proof. by elim/big_rec2: _ => [|i p q _ <-]; rewrite ?(rmod0p, rmodpD). 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
rmodp_sum
rmodp_mulmrp q : rmodp (p * (rmodp q d)) d = rmodp (p * q) d. Proof. by rewrite [q in RHS]rdivp_eq mulrDr rmodpD mulrA rmodp_mull add0r. 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
rmodp_mulmr
rdvdpp: rdvdp d d. Proof. by apply: rdvdpp; rewrite (eqP mond); [apply: commr1 | apply: rreg1]. 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
rdvdpp
eq_rdvdpq1 p : p = q1 * d -> rdvdp d p. Proof.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
eq_rdvdp
rdvdp_mullp : rdvdp d (p * d). Proof. by apply: rdvdp_mull; rewrite (eqP mond) //; [apply: commr1 | apply: rreg1]. 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
rdvdp_mull
rdvdpPp : reflect (exists qq, p = qq * d) (rdvdp d p). Proof. case: (monic_comreg mond)=> Hc Hr; apply: (iffP idP) => [|[qq] /eq_rdvdp //]. by case: rdvdp_eqP=> // k qq; rewrite (eqP mond) expr1n mulr1 => ->; exists qq. 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
rdvdpP
rdivpKp : rdvdp d p -> (rdivp p d) * d = p. Proof. by move=> dvddp; rewrite [RHS]rdivp_eq rmodp_eq0 ?addr0. 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
rdivpK
drop_poly_rdivpn p : drop_poly n p = rdivp p 'X^n. Proof. rewrite -[p in RHS](poly_take_drop n) addrC rdivp_addl_mul ?monicXn//. by rewrite rdivp_small ?addr0// size_polyXn ltnS size_take_poly. 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
drop_poly_rdivp
take_poly_rmodpn p : take_poly n p = rmodp p 'X^n. Proof. have mX := monicXn R n; rewrite -[p in RHS](poly_take_drop n) rmodpD//. by rewrite rmodp_small ?rmodp_mull ?addr0// size_polyXn ltnS size_take_poly. 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
take_poly_rmodp
rmodp_mulmlp q : rmodp (rmodp p d * q) d = rmodp (p * q) d. Proof. by rewrite [in LHS]mulrC [in RHS]mulrC rmodp_mulmr. 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
rmodp_mulml
rmodpXp n : rmodp ((rmodp p d) ^+ n) d = rmodp (p ^+ n) d. Proof. elim: n => [|n IH]; first by rewrite !expr0. rewrite !exprS -rmodp_mulmr // IH rmodp_mulmr //. by rewrite mulrC rmodp_mulmr // 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
rmodpX
rmodp_comprp q : rmodp (p \Po (rmodp q d)) d = (rmodp (p \Po q) d). Proof. elim/poly_ind: p => [|p c IH]; first by rewrite !comp_polyC !rmod0p. rewrite !comp_polyD !comp_polyM addrC rmodpD //. rewrite mulrC -rmodp_mulmr // IH rmodp_mulmr //. rewrite !comp_polyX !comp_polyC. by rewrite mulrC rmodp_mulmr // -rmodpD // 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
rmodp_compr
rdivp1p : rdivp p 1 = p. Proof. by rewrite -[p in LHS]mulr1 rdivp_mull // monic1. 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
rdivp1
rdvdp_XsubClp x : rdvdp ('X - x%:P) p = root p x. Proof. have [HcX Hr] := monic_comreg (monicXsubC x). apply/rmodp_eq0P/factor_theorem => [|[p1 ->]]; last exact/rmodp_mull/monicXsubC. move=> e0; exists (rdivp p ('X - x%:P)). by rewrite [LHS](rdivp_eq (monicXsubC x)) e0 addr0. 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
rdvdp_XsubCl
polyXsubCPp x : reflect (p.[x] = 0) (rdvdp ('X - x%:P) p). Proof. by apply: (iffP idP); rewrite rdvdp_XsubCl; move/rootP. 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
polyXsubCP
root_factor_theoremp x : root p x = (rdvdp ('X - x%:P) p). Proof. by rewrite rdvdp_XsubCl. 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_factor_theorem
redivp_spec(m d : {poly R}) : nat * {poly R} * {poly R} -> Type := EdivnSpec k (q r: {poly R}) of (lead_coef d ^+ k) *: m = q * d + r & (d != 0 -> size r < size d) : redivp_spec m d (k, q, 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
redivp_spec
redivpPm d : redivp_spec m d (redivp m d). Proof. rewrite redivp_def; constructor; last by move=> dn0; rewrite ltn_rmodp. by rewrite -mul_polyC mulrC rdivp_eq //= /GRing.comm 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
redivpP
rdivp_eqd p : (lead_coef d ^+ rscalp p d) *: p = rdivp p d * d + rmodp p d. Proof. by rewrite /rdivp /rmodp /rscalp; case: redivpP=> k q1 r1 Hc _; apply: Hc. 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
rdivp_eq
rdvdp_eqPd p : rdvdp_spec p d (rmodp p d) (rdvdp d p). Proof. case hdvd: (rdvdp d p); last by move/rmodp_eq0P/eqP/RdvdpN: hdvd. move/rmodp_eq0P: (hdvd)->; apply: (@Rdvdp _ _ _ (rscalp p d) (rdivp p d)). by rewrite mulrC mul_polyC rdivp_eq; move/rmodp_eq0P: (hdvd)->; rewrite addr0. 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
rdvdp_eqP
rdvdp_eqq p : rdvdp q p = (lead_coef q ^+ rscalp p q *: p == rdivp p q * q). Proof. rewrite rdivp_eq; apply/rmodp_eq0P/eqP => [->|/eqP]; first by rewrite addr0. by rewrite eq_sym addrC -subr_eq subrr; move/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
rdvdp_eq
uniq_roots_rdvdpp rs : all (root p) rs -> uniq_roots rs -> rdvdp (\prod_(z <- rs) ('X - z%:P)) p. Proof. move=> rrs /(uniq_roots_prod_XsubC rrs) [q ->]. exact/RingMonic.rdvdp_mull/monic_prod_XsubC. 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
uniq_roots_rdvdp
edivp_expanded_defp q := let: (k, d, r) as edvpq := redivp p q in if lead_coef q \in GRing.unit then (0, (lead_coef q)^-k *: d, (lead_coef q)^-k *: r) else edvpq. Fact edivp_key : unit. Proof. by []. Qed.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
edivp_expanded_def
edivp:= locked_with edivp_key edivp_expanded_def.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
edivp
edivp_unlockable:= [unlockable fun edivp].
Canonical
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
edivp_unlockable
divpp q := ((edivp p q).1).2.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
divp
modpp q := (edivp p q).2.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
modp
scalpp q := ((edivp p q).1).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
scalp
dvdpp q := modp q p == 0.
Definition
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
dvdp
eqpp q := (dvdp p q) && (dvdp q 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
eqp
edivp_defp q : edivp p q = (scalp p q, divp p q, modp p q). Proof. by rewrite /scalp /divp /modp; case: (edivp 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
edivp_def
edivp_redivpp q : lead_coef q \in GRing.unit = false -> edivp p q = redivp p q. Proof. by move=> hu; rewrite unlock hu; case: (redivp 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
edivp_redivp
divpEp q : p %/ q = if lead_coef q \in GRing.unit then lead_coef q ^- rscalp p q *: rdivp p q else rdivp p q. Proof. by case: ifP; rewrite /divp unlock redivp_def => ->. 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
divpE
modpEp q : p %% q = if lead_coef q \in GRing.unit then lead_coef q ^- rscalp p q *: (rmodp p q) else rmodp p q. Proof. by case: ifP; rewrite /modp unlock redivp_def => ->. 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
modpE
scalpEp q : scalp p q = if lead_coef q \in GRing.unit then 0 else rscalp p q. Proof. by case: ifP; rewrite /scalp unlock redivp_def => ->. 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
scalpE
dvdpEp q : p %| q = rdvdp p q. Proof. rewrite /dvdp modpE /rdvdp; case ulcq: (lead_coef p \in GRing.unit)=> //. rewrite -[in LHS]size_poly_eq0 size_scale ?size_poly_eq0 //. by rewrite invr_eq0 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
dvdpE
lc_expn_scalp_neq0p q : lead_coef q ^+ scalp p q != 0. Proof. have [->|nzq] := eqVneq q 0; last by rewrite expf_neq0 ?lead_coef_eq0. by rewrite /scalp 2!unlock /= eqxx lead_coef0 unitr0 /= oner_neq0. Qed. Hint Resolve lc_expn_scalp_neq0 : core.
Lemma
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
lc_expn_scalp_neq0
edivp_spec(m d : {poly R}) : nat * {poly R} * {poly R} -> bool -> Type := |Redivp_spec k (q r: {poly R}) of (lead_coef d ^+ k) *: m = q * d + r & lead_coef d \notin GRing.unit & (d != 0 -> size r < size d) : edivp_spec m d (k, q, r) false |Fedivp_spec (q r: {poly R}) of m = q * d + r & (lead_coef d \in GRing.unit) & (d != 0 -> size r < size d) : edivp_spec m d (0, q, r) true.
Variant
algebra
[ "From mathcomp Require Import ssreflect ssrfun ssrbool eqtype ssrnat seq choice", "From mathcomp Require Import fintype bigop ssralg poly" ]
algebra/polydiv.v
edivp_spec
edivpPm d : edivp_spec m d (edivp m d) (lead_coef d \in GRing.unit). Proof. have hC : GRing.comm d (lead_coef d)%:P by rewrite /GRing.comm mulrC. case ud: (lead_coef d \in GRing.unit); last first. rewrite edivp_redivp // redivp_def; constructor; rewrite ?ltn_rmodp // ?ud //. by rewrite rdivp_eq. have cdn0: lead_coef d != 0 by apply: contraTneq ud => ->; rewrite unitr0. rewrite unlock ud redivp_def; constructor => //. rewrite -scalerAl -scalerDr -mul_polyC. have hn0 : (lead_coef d ^+ rscalp m d)%:P != 0. by rewrite polyC_eq0; apply: expf_neq0. apply: (mulfI hn0); rewrite !mulrA -exprVn !polyC_exp -exprMn -polyCM. by rewrite divrr // expr1n mul1r -polyC_exp mul_polyC rdivp_eq. move=> dn0; rewrite size_scale ?ltn_rmodp // -exprVn expf_eq0 negb_and. by rewrite invr_eq0 cdn0 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
edivpP
edivp_eqd q r : size r < size d -> lead_coef d \in GRing.unit -> edivp (q * d + r) d = (0, q, r). Proof. have hC : GRing.comm d (lead_coef d)%:P by apply: mulrC. move=> hsrd hu; rewrite unlock hu; case et: (redivp _ _) => [[s qq] rr]. have cdn0 : lead_coef d != 0 by case: eqP hu => //= ->; rewrite unitr0. move: (et); rewrite RingComRreg.redivp_eq //; last exact/rregP. rewrite et /= mulrC (mulrC r) !mul_polyC; case=> <- <-. by rewrite !scalerA mulVr ?scale1r // unitrX. 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
edivp_eq
divp_eqp q : (lead_coef q ^+ scalp p q) *: p = (p %/ q) * q + (p %% q). Proof. rewrite divpE modpE scalpE. case uq: (lead_coef q \in GRing.unit); last by rewrite rdivp_eq. rewrite expr0 scale1r; have [->|qn0] := eqVneq q 0. by rewrite lead_coef0 expr0n /rscalp unlock eqxx invr1 !scale1r rmodp0 !simp. by rewrite -scalerAl -scalerDr -rdivp_eq scalerA mulVr (scale1r, unitrX). 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_eq
dvdp_eqq p : (q %| p) = (lead_coef q ^+ scalp p q *: p == (p %/ q) * q). Proof. rewrite dvdpE rdvdp_eq scalpE divpE; case: ifP => ulcq //. rewrite expr0 scale1r -scalerAl; apply/eqP/eqP => [<- | {2}->]. by rewrite scalerA mulVr ?scale1r // unitrX. by rewrite scalerA mulrV ?scale1r // unitrX. 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_eq
divpKd p : d %| p -> p %/ d * d = (lead_coef d ^+ scalp p d) *: p. Proof. by rewrite dvdp_eq; move/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
divpK
divpKCd p : d %| p -> d * (p %/ d) = (lead_coef d ^+ scalp p d) *: p. Proof. by move=> ?; rewrite mulrC divpK. 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
divpKC