@@ -2088,9 +2088,10 @@ Qed.
20882088End Closed_Ball_normedModType.
20892089
20902090Section InfiniteNorm.
2091- Variables (R : numFieldType) (V : vectType R) (B : (\dim (@fullv _ V)).-tuple V) .
2091+ Variables (R : numFieldType) (V : vectType R).
20922092Let V' := @fullv _ V.
2093- Hypothesis (Bbasis : basis_of V' B).
2093+ Variable B : (\dim V').-tuple V.
2094+ Hypothesis Bbasis : basis_of V' B.
20942095
20952096Definition oo_norm x := \big[Order.max/0]_(i < \dim V') `|coord B i x|.
20962097
@@ -2103,40 +2104,31 @@ HB.instance Definition _ := Pointed.copy oo_space V^o.
21032104Lemma oo_norm_ge0 x : 0 <= oo_norm x.
21042105Proof .
21052106rewrite /oo_norm.
2106- elim: (index_enum _) => /=; first by rewrite big_nil.
2107- by move=> i l IHl; rewrite big_cons /Order.max/=; case: ifP.
2107+ by elim/big_ind : _ => //= ? ? ? ?; rewrite /Order.max; case: ifP.
21082108Qed .
21092109
21102110Lemma le_coord_oo_norm x i : `|coord B i x| <= oo_norm x.
21112111Proof .
21122112rewrite /oo_norm; elim: (index_enum _) (mem_index_enum i) => //= j l IHl.
2113- rewrite inE big_cons /Order.max/= => /orP[/eqP <-|/IHl {}IHl];
2114- case: ifP => [/ltW|]//.
2115- move=> /negP/negP.
2116- have bR: \big[Order.max/0]_(i <- l) `|coord B i x| \is Num.real.
2117- exact: bigmax_real.
2118- move: (real_comparable bR (normr_real (coord B j x))).
2119- by move=> /comparable_leNgt <- /(le_trans IHl).
2113+ rewrite inE big_cons [X in _ <= X _ _]/Order.max/= => /predU1P[<-|/IHl {}IHl];
2114+ case: ifP => [/ltW|]// /negbT.
2115+ set b := (X in _ < X); have bR : b \is Num.real by exact: bigmax_real.
2116+ have /comparable_leNgt <- := real_comparable bR (normr_real (coord B j x)).
2117+ by move=> /(le_trans IHl).
21202118Qed .
21212119
21222120Lemma ler_oo_normD x y : oo_norm (x + y) <= oo_norm x + oo_norm y.
21232121Proof .
2124- apply: bigmax_le => [|/= i _].
2125- by apply: addr_ge0; apply: oo_norm_ge0.
2126- rewrite raddfD/=.
2127- by apply/(le_trans (ler_normD _ _))/lerD; apply: le_coord_oo_norm.
2122+ apply: bigmax_le => [|/= i _]; first by rewrite addr_ge0// oo_norm_ge0.
2123+ by rewrite raddfD/= (le_trans (ler_normD _ _))// lerD// le_coord_oo_norm.
21282124Qed .
21292125
21302126Lemma oo_norm0_eq0 x : oo_norm x = 0 -> x = 0.
21312127Proof .
2132- move=> x0.
2133- rewrite (coord_basis Bbasis (memvf x)).
2128+ move=> x0; rewrite (coord_basis Bbasis (memvf x)).
21342129suff: forall i, coord B i x = 0.
2135- move=> {}x0.
2136- under eq_bigr do rewrite x0.
2137- by rewrite -scaler_sumr scale0r.
2138- move=> i; apply/normr0_eq0/le_anti/andP; split; last exact: normr_ge0.
2139- by rewrite -x0; apply: le_coord_oo_norm.
2130+ by move=> {}x0; rewrite big1//= => j _; rewrite x0 scale0r.
2131+ by move=> i; apply/normr0_eq0/le_anti; rewrite normr_ge0 -x0 le_coord_oo_norm.
21402132Qed .
21412133
21422134Lemma oo_normZ r x : oo_norm (r *: x) = `|r| * oo_norm x.
@@ -2174,124 +2166,85 @@ Let Voo := oo_space (vbasisP (@fullv _ V)).
21742166(* N.B. Get Trocq to prove the continuity part automatically. *)
21752167Lemma oo_closed_ball_compact : compact (closed_ball (0 : Voo) 1).
21762168Proof .
2177- rewrite closed_ballE/closed_ball_//= .
2169+ rewrite closed_ballE// /closed_ball_ .
21782170under eq_set do rewrite sub0r normrN.
21792171rewrite -[forall x, _]/(compact _).
2180- pose f (X : {ptws 'I_(\dim V') -> R^o }) : Voo :=
2181- \sum_(i < \dim V') ( X i) *: (vbasis V')`_i.
2182- have -> :
2183- [set x : Voo | `|x| <= 1] = f @` [set X | forall i, `[-1, 1]%classic (X i)].
2184- apply/seteqP; split=> x/=.
2185- move=> x1; exists (fun i => coord (vbasis V') i x); last first.
2172+ pose f (X : {ptws 'I_(\dim V') -> R}) : Voo :=
2173+ \sum_(i < \dim V') X i *: (vbasis V')`_i.
2174+ have -> : [set x : Voo | `|x| <= 1] =
2175+ f @` [set X | forall i, `[-1, 1]%classic (X i)].
2176+ apply/seteqP; split=> [ x/= x1|x/= [X X1 <-]] .
2177+ - exists (coord (vbasis V') ^~ x); last first.
21862178 exact/esym/(@coord_vbasis _ _ (x : V))/memvf.
2187- move=> i; rewrite in_itv/= -ler_norml.
2188- apply: (le_trans _ x1).
2189- exact: le_coord_oo_norm.
2190- move=> [X] X1 <-.
2191- rewrite /normr/=/oo_norm.
2192- apply: bigmax_le => //= i _.
2193- rewrite coord_sum_free; last exact/basis_free/vbasisP.
2194- rewrite ler_norml.
2195- exact: X1.
2196- apply: (@continuous_compact _ _ f); last first.
2197- apply: (@tychonoff 'I_(\dim V') (fun=> R^o) (fun=> `[-1, 1 : R^o]%classic)).
2198- move=> _.
2179+ by move=> i; rewrite in_itv/= -ler_norml (le_trans _ x1)// le_coord_oo_norm.
2180+ - rewrite /normr/= /oo_norm bigmax_le => //= i _.
2181+ by rewrite coord_sum_free ?ler_norml; [exact: X1|exact/basis_free/vbasisP].
2182+ apply: (@continuous_compact _ _ f).
2183+ - apply/continuous_subspaceT/sum_continuous => /= i _ x.
2184+ exact/continuousZr_tmp/proj_continuous.
2185+ - apply: (@tychonoff 'I_(\dim V') (fun=> R^o) (fun=> `[-1, 1]%classic)) => _.
21992186 exact: segment_compact.
2200- apply/continuous_subspaceT/sum_continuous => i _/= x.
2201- exact/continuousZl/proj_continuous.
22022187Qed .
22032188
22042189Lemma equivalence_norms (N : V -> R) :
22052190 N 0 = 0 -> (forall x, 0 <= N x) -> (forall x, N x = 0 -> x = 0) ->
22062191 (forall x y, N (x + y) <= N x + N y) ->
22072192 (forall r x, N (r *: x) = `|r| * N x) ->
2208- exists M, 0 < M /\ forall x : Voo, `|x| <= M * N x /\ N x <= M * `|x|.
2193+ exists2 M, 0 < M & forall x : Voo, `|x| <= M * N x /\ N x <= M * `|x|.
22092194Proof .
22102195move=> N0 N_ge0 N0_eq0 ND NZ.
22112196set M0 := 1 + \sum_(i < \dim V') N (vbasis V')`_i.
2212- have N_sum (I : Type) (r : seq I) (F : I -> V):
2213- N (\sum_(i <- r) F i) <= \sum_(i <- r) N (F i).
2214- elim: r => [|x r IHr]; first by rewrite !big_nil N0.
2215- by rewrite !big_cons; apply/(le_trans (ND _ _))/lerD.
2216- have leNoo: forall x : Voo, N x <= M0 * `|x|.
2217- move=> x.
2218- rewrite [in leLHS](coord_vbasis (memvf (x : V))).
2219- apply: (le_trans (N_sum _ _ _)).
2220- rewrite mulrDl mul1r mulr_suml -[leLHS]add0r.
2221- apply: lerD => //.
2222- apply: ler_sum => /= i _.
2223- rewrite NZ mulrC; apply: ler_pM => //.
2224- exact: le_coord_oo_norm.
2225- have M00 : 0 < M0.
2226- rewrite -[ltLHS]addr0.
2227- by apply: ltr_leD => //; apply: sumr_ge0.
2197+ have M00 : 0 < M0 by rewrite ltr_pwDl// sumr_ge0.
2198+ have N_sum (I : Type) (r : seq I) (F : I -> V) :
2199+ N (\sum_(i <- r) F i) <= \sum_(i <- r) N (F i).
2200+ by elim/big_ind2 : _ => *; rewrite ?N0// (le_trans (ND _ _))// lerD.
2201+ have leNoo (x : Voo) : N x <= M0 * `|x|.
2202+ rewrite [in leLHS](coord_vbasis (memvf (x : V))) (le_trans (N_sum _ _ _))//.
2203+ rewrite mulrDl mul1r mulr_suml ler_wpDl// ler_sum => //= i _.
2204+ by rewrite NZ mulrC ler_pM// le_coord_oo_norm.
2205+ have NZN a : N (- a) = N a by rewrite -scaleN1r NZ normrN1 mul1r.
22282206have NC0 : continuous (N : Voo -> R).
2229- move=> /= x.
2230- rewrite /continuous_at.
2207+ move=> /= x; rewrite /continuous_at.
22312208 apply: cvg_zero; first exact: nbhs_filter.
22322209 apply/cvgr0Pnorm_le; first exact: nbhs_filter.
22332210 move=> /= e e0.
22342211 near=> y.
2235- rewrite -[_ y]/(N y - N x).
2236- apply: (@le_trans _ _ (N (y - x))).
2237- apply/real_ler_normlP.
2238- by apply: realB; apply: ger0_real.
2239- have NB a b : N a <= N b + N (a - b).
2240- by rewrite -[a in N a]addr0 -(subrr b) addrCA ND.
2241- rewrite opprB !lerBlDl; split; last exact: NB.
2242- by rewrite -opprB -scaleN1r NZ normrN1 mul1r NB.
2243- apply: (le_trans (leNoo _)).
2244- rewrite mulrC -ler_pdivlMr// -opprB normrN.
2245- near: y; apply: cvgr_dist_le; first exact: cvg_id.
2246- exact: divr_gt0.
2212+ rewrite -[_ y]/(N y - N x) (@le_trans _ _ (N (y - x)))//.
2213+ apply/ler_normlP.
2214+ have NB a b : N a <= N b + N (a - b).
2215+ by rewrite (le_trans _ (ND _ _)) ?subrKC.
2216+ by rewrite opprB !lerBlDl NB -opprB NZN NB.
2217+ rewrite (le_trans (leNoo _))// mulrC -ler_pdivlMr// -opprB normrN.
2218+ by near: y; apply: cvgr_dist_le; [exact: cvg_id|exact: divr_gt0].
22472219have: compact [set x : Voo | `|x| = 1].
2248- apply: (subclosed_compact _ oo_closed_ball_compact); last first.
2249- apply/subsetP => x.
2250- rewrite closed_ballE// !inE/=.
2251- by rewrite /closed_ball_/= sub0r normrN => ->.
2252- apply: (@closed_comp _ _ _ [set 1 : R]); last exact: closed_eq.
2253- by rewrite /prop_in1 => + _; apply: norm_continuous.
2220+ apply: (subclosed_compact _ oo_closed_ball_compact).
2221+ - apply: (@closed_comp _ _ _ [set 1 : R]); last exact: closed_eq.
2222+ by move=> *; exact: norm_continuous.
2223+ - by move => x/=; rewrite closed_ballE// /closed_ball_/= sub0r normrN => ->.
22542224move=> /(@continuous_compact _ _ (N : Voo -> R)) -/(_ _)/wrap[].
22552225 exact: continuous_subspaceT.
22562226move=> /(@continuous_compact _ _ (@GRing.inv R)) -/(_ _)/wrap[].
2257- move=> /= x.
2258- rewrite /continuous_at.
2227+ move=> /= x; rewrite /continuous_at.
22592228 apply: (@continuous_in_subspaceT _ _
22602229 [set N x | x in [set x : Voo | `|x| = 1]] (@GRing.inv R)).
2261- move=> r /set_mem/=[] y y1 <-.
2230+ move=> /= r /set_mem/= [ y y1 <-] .
22622231 apply: inv_continuous.
2263- apply/negP => /eqP/N0_eq0 y0.
2264- move: y1; rewrite y0 normr0 => /esym.
2265- by move: (@oner_neq0 R) => /eqP.
2266- move=> /compact_bounded[] M1 [] M1R /(_ (1 + M1)).
2267- rewrite -subr_gt0 -addrA subrr addr0 => /(_ ltr01).
2232+ by apply: contra_eq_neq y1 => /N0_eq0 ->; rewrite normr0 eq_sym oner_eq0.
2233+ move=> /compact_bounded[M1 [M1R /(_ (1 + M1))]] /(_ (ltr_pwDl ltr01 (lexx _))).
22682234rewrite /globally/= => M1N.
2269- exists (maxr M0 (1 + M1)).
2270- split=> [|x]; first by apply: (lt_le_trans M00); rewrite le_max lexx.
2271- split; last first.
2272- apply/(le_trans (leNoo x))/ler_pM => //; first exact/ltW.
2273- by rewrite /maxr; case: ifP => // /ltW.
2235+ exists (maxr M0 (1 + M1)) => [|x]; first by rewrite lt_max M00.
2236+ split; last by rewrite (le_trans (leNoo x))// ler_wpM2r// le_max lexx.
22742237have [->|x0] := eqVneq x 0; first by rewrite normr0 N0 mulr0.
2275- have Nx0: 0 < N x.
2276- rewrite lt0r N_ge0 andbT.
2277- by move: x0; apply: contra => /eqP/N0_eq0/eqP.
2278- have normx0 : 0 < `|x|.
2279- move: (lt_le_trans Nx0 (leNoo x)).
2280- by rewrite pmulr_rgt0.
2238+ have Nx0 : 0 < N x.
2239+ by rewrite lt0r N_ge0 andbT; move: x0; apply: contra_neq => /N0_eq0.
2240+ have normx0 : 0 < `|x| by rewrite normr_gt0.
22812241move: M1N => /(_ (`|x| / N x)) -/(_ _)/wrap[].
22822242 exists (N x / `|x|); last by rewrite invf_div.
2283- exists (`|x|^-1 *: x); last first.
2284- by rewrite NZ mulrC ger0_norm.
2285- rewrite normrZ mulrC ger0_norm.
2286- by rewrite divrr//; apply: unitf_gt0.
2287- by rewrite invr_ge0; apply: ltW.
2288- rewrite ger0_norm; last exact: divr_ge0.
2289- rewrite ler_pdivrMr// => xle.
2290- apply: (le_trans xle).
2291- rewrite -subr_ge0 -mulrBl pmulr_lge0// subr_ge0.
2292- by rewrite le_max lexx orbT.
2293- Unshelve. all: by end_near.
2294- Qed .
2243+ exists (`|x|^-1 *: x); last by rewrite NZ mulrC ger0_norm.
2244+ by rewrite normrZ normfV normr_id mulVf// gt_eqF.
2245+ rewrite ger0_norm ?divr_ge0// ler_pdivrMr// => /le_trans; apply.
2246+ by rewrite ler_pM2r// le_max lexx orbT.
2247+ Unshelve. all: by end_near. Qed .
22952248
22962249End EquivalenceNorms.
22972250
@@ -2301,26 +2254,22 @@ Variables (R : realType) (V : normedVectType R) (W : normedModType R).
23012254Lemma linear_findim_continuous (f : {linear V -> W}) : continuous f.
23022255Proof .
23032256set V' := @fullv _ V.
2304- set B := vbasis V' => /= x .
2305- rewrite /continuous_at.
2257+ set B := vbasis V'.
2258+ move=> /= x; rewrite /continuous_at.
23062259rewrite [x in f x](coord_vbasis (memvf x)) raddf_sum.
23072260rewrite (@eq_cvg _ _ _ _ (fun y => \sum_(i < \dim V') coord B i y *: f B`_i));
23082261 last first.
23092262 move=> y; rewrite [y in LHS](coord_vbasis (memvf y)) raddf_sum.
23102263 by apply: eq_big => // i _; apply: linearZ.
23112264apply: cvg_sum => i _.
23122265rewrite [X in _ --> X]linearZ/= -/B.
2313- apply: cvgZl .
2266+ apply: cvgZr_tmp .
23142267move: x; apply/linear_bounded_continuous/bounded_funP => r/=.
2315- have := @equivalence_norms R V (@normr R V) (@normr0 _ _) (@normr_ge0 _ _)
2316- (@normr0_eq0 _ _) (@ler_normD _ _) (@normrZ _ _).
2317- move=> [] M [] M0 MP.
2268+ have [M M0 MP] := @equivalence_norms R V (@normr R V) (@normr0 _ _)
2269+ (@normr_ge0 _ _) (@normr0_eq0 _ _) (@ler_normD _ _) (@normrZ _ _).
23182270exists (M * r) => x.
2319- move: MP => /(_ x)[] Mx Mx' xr.
2320- apply/(le_trans (le_coord_oo_norm _ _ _))/(le_trans Mx).
2321- rewrite -subr_ge0 -mulrBr; apply: mulr_ge0; first exact: ltW.
2322- by rewrite subr_ge0.
2271+ move: MP => /(_ x) [Mx _] xr.
2272+ by rewrite (le_trans (le_coord_oo_norm _ _ _))// (le_trans Mx) ?ler_wpM2l// ltW.
23232273Qed .
23242274
23252275End LinearContinuous.
2326-
0 commit comments