Some Classes of Function Spaces, Their Properties, and Applications
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The Semi-M Property for Normed Riesz Spaces Compositio Mathematica, Tome 34, No 2 (1977), P
COMPOSITIO MATHEMATICA EP DE JONGE The semi-M property for normed Riesz spaces Compositio Mathematica, tome 34, no 2 (1977), p. 147-172 <http://www.numdam.org/item?id=CM_1977__34_2_147_0> © Foundation Compositio Mathematica, 1977, tous droits réservés. L’accès aux archives de la revue « Compositio Mathematica » (http: //http://www.compositio.nl/) implique l’accord avec les conditions géné- rales d’utilisation (http://www.numdam.org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infrac- tion pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright. Article numérisé dans le cadre du programme Numérisation de documents anciens mathématiques http://www.numdam.org/ COMPOSITIO MATHEMATICA, Vol. 34, Fasc. 2, 1977, pag. 147-172 Noordhoff International Publishing Printed in the Netherlands THE SEMI-M PROPERTY FOR NORMED RIESZ SPACES Ep de Jonge 1. Introduction It is well-known that if (0394, F, IL) is a u-finite measure space and if 1 ~ p 00, then the Banach dual L *p of the Banach space Lp = Lp(0394, IL) can be identified with Lq = Lq(L1, 03BC), where p-1 + q-1 = 1. For p =00 the situation is different; the space Li is a linear subspace of L*, and only in a very trivial situation (the finite-dimensional case) we have Li = Lfi. Restricting ourselves to the real case, the Banach dual L *~ is a (real) Riesz space, i.e., a vector lattice, and Li is now a band in L*. The disjoint complement (i.e., the set of all elements in L* disjoint to all elements in LI) is also a band in L*, called the band of singular linear functionals on Loo. -
Burkholder's Inequalities in Noncommutative Lorentz
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 138, Number 7, July 2010, Pages 2431–2441 S 0002-9939(10)10267-6 Article electronically published on March 24, 2010 BURKHOLDER’S INEQUALITIES IN NONCOMMUTATIVE LORENTZ SPACES YONG JIAO (Communicated by Marius Junge) Abstract. We prove Burkholder’s inequalities in noncommutative Lorentz spaces Lp,q(M), 1 <p<∞, 1 ≤ q<∞, associated with a von Neumann algebra M equipped with a faithful normal tracial state. These estimates generalize the classical inequalities in the commutative case. 1. Introduction Martingale inequalities and sums of independent random variables are important tools in classical harmonic analysis. A fundamental result due to Burkholder [1, 2] can be stated as follows. Given a probability space (Ω, F ,P), let {Fn}n≥1 be a nondecreasing sequence of σ-fields of F such that F = ∨Fn and let En be the conditional expectation operator relative to Fn. Given 2 ≤ p<∞ and an p L -bounded martingale f =(fn)n≥1, we have ∞ ∞ 1/2 1/p 2 p (1.1) fLp ≈ Ek−1(|df k| ) + |df k| . Lp Lp k=1 k=1 The first term on the right is called the conditioned square function of f, while the second is called the p-variation of f. Rosenthal’s inequalities [14] can be regarded as the particular case where the sequence df =(df 1,df2, ...) is a family of independent mean-zero random variables df k = ak. In this case it is easy to reduce Rosenthal’s inequalities to ∞ ∞ ∞ 1/2 1/p ≈ 2 p (1.2) ak Lp ak 2 + ak p . -
Arxiv:1712.01188V2 [Math.AP]
GREEN’S FUNCTION FOR SECOND ORDER ELLIPTIC EQUATIONS WITH SINGULAR LOWER ORDER COEFFICIENTS SEICK KIM AND GEORGIOS SAKELLARIS Abstract. We construct Green’s function for second order elliptic operators of the form Lu = −∇ · (A∇u + bu) + c · ∇u + du in a domain and obtain pointwise bounds, as well as Lorentz space bounds. We assume that the matrix of principal coefficients A is uniformly elliptic and bounded and the lower order coefficients b, c, and d belong to certain Lebesgue classes and satisfy the condition d −∇· b ≥ 0. In particular, we allow the lower order coefficients to be singular. We also obtain the global pointwise bounds for the gradient of Green’s function in the case when the mean oscillations of the coefficients A and b satisfy the Dini conditions and the domain is C1,Dini. 1. Introduction Let Ω be a domain (i.e., an open connected set) in Rn with n ≥ 3. We consider second order elliptic operators in divergence form n n ij i i Lu = − Di(a (x)Dju + b (x)u) + c (x)Diu + d(x)u, iX,j=1 Xi=1 which hereafter shall be abbreviated as Lu = − div(A∇u + bu) + c · ∇u + du. We assume that the principal coefficients A = (aij) are measurable n × n matrices that are bounded and uniformly elliptic; i.e. there is a constant λ> 0 such that n λ|ξ|2 ≤ A(x)ξ · ξ = aij(x)ξiξj, ∀x ∈ Ω, ∀ξ ∈ Rn. (1.1) iX,j=1 We also assume that the lower order coefficients b = (b1,..., bn), c = (c1,..., cn), and d are such that b ∈ Lq(Ω), c ∈ Lr(Ω), d ∈ Ls(Ω) for some q, r ≥ n, s ≥ n/2. -
Fourier Analysis in Function Space Theory
Course No. 401-4463-62L Fourier Analysis in Function Space Theory Dozent: Tristan Rivi`ere Assistant: Alessandro Pigati Contents 1 The Fourier transform of tempered distributions 1 1.1 The Fourier transforms of L1 functions . 1 1.2 The Schwartz Space S(Rn)........................... 4 1.3 Frechet Spaces . 6 1.4 The space of tempered distributions S0(Rn).................. 12 1.5 Convolutions in S0(Rn)............................. 21 2 The Hardy-Littlewood Maximal Function 26 2.1 Definition and elementary properties. 26 2.2 Hardy-Littlewood Lp−theorem for the Maximal Function. 27 2.3 The limiting case p =1. ............................ 30 3 Quasi-normed vector spaces 32 3.1 The Metrizability of quasi-normed vector spaces . 32 3.2 The Lorentz spaces Lp;1 ............................ 36 3.3 Decreasing rearrangement . 37 3.4 The Lorentz spaces Lp;q ............................ 39 3.5 Functional inequalities for Lorentz spaces . 44 3.6 Dyadic characterization of some Lorentz spaces and another proof of Lorentz{ Sobolev embedding (optional) . 49 4 The Lp−theory of Calder´on-Zygmund convolution operators. 52 4.1 Calder´on-Zygmund decompositions. 52 4.2 An application of Calder´on-Zygmund decomposition . 54 4.3 The Marcinkiewicz Interpolation Theorem - The Lp case . 56 4.4 Calderon Zygmund Convolution Operators over Lp ............. 58 4.4.1 A \primitive" formulation . 60 4.4.2 A singular integral type formulation . 64 4.4.3 The case of homogeneous kernels . 69 4.4.4 A multiplier type formulation . 71 4.4.5 Applications: The Lp theory of the Riesz Transform and the Laplace and Bessel Operators . 74 4.4.6 The limiting case p =1........................ -
Weak-Type Weights and Normable Lorentz Spaces 1
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY Volume 124, Number 3, March 1996 WEAK-TYPE WEIGHTS AND NORMABLE LORENTZ SPACES MAR´IA J. CARRO, ALEJANDRO GARC´IA DEL AMO, AND JAVIER SORIA (Communicated by J. Marshall Ash) Abstract. We show that the Lorentz space Λ1(w) is a Banach space if and only if the Hardy-Littlewood maximal operator M satisfies a certain weak-type estimate. We also consider the case of general measures. Finally, we study some properties of several indices associated to these spaces. 1. Introduction We are going to study weighted Lorentz spaces of functions defined in Rn as follows (for standard notation we refer to [BS] and [GR]): If u is a weight in Rn, + w is a weight in R , fu∗ denotes the decreasing rearrangement of f with respect to the measure u(x) dx and 0 <p< , we define ∞ 1/p ∞ p p p Λu(w)= f; f Λu(w) = fu∗(t) w(t)dt < . k k 0 ∞ Z If u 1, we will only write Λp(w). Classical examples are obtained by choosing ≡ (p/q) 1 p q,p w(t)=t − .InthiscaseΛ(w)=L . A classical result of G.G. Lorentz (see [Lo]) shows that Λ1(w) is a norm, if and only if, w is a decreasing function. The problem of findingk·k conditions on w so that Λp(w) is a Banach space (that is, there exists a norm equivalent to Λp(w)) was solved, for p>1, by E. Sawyer ([Sa]). This condition is that the Hardy-Littlewoodk·k maximal operator is bounded on Λp(w). -
HARDY-TYPE OPERATORS in LORENTZ-TYPE SPACES DEFINED on MEASURE SPACES1 Qinxiu Sun∗, Xiao Yu∗∗ and Hongliang Li∗∗∗
Indian J. Pure Appl. Math., 51(3): 1105-1132, September 2020 °c Indian National Science Academy DOI: 10.1007/s13226-020-0453-1 HARDY-TYPE OPERATORS IN LORENTZ-TYPE SPACES DEFINED ON MEASURE SPACES1 Qinxiu Sun¤, Xiao Yu¤¤ and Hongliang Li¤¤¤ ¤Department of Mathematics, Zhejiang University of Science and Technology, Hangzhou 310023, China ¤¤Department of Mathematics, Shangrao Normal University, Shangrao 334001, China ¤¤¤Department of Mathematics, Zhejiang International Studies University, Hangzhou 310012, China e-mail: [email protected] (Received 2 June 2018; accepted 12 June 2019) Weight criteria for the boundedness and compactness of generalized Hardy-type operators Z T f(x) = u1(x) f(y)u2(y)v0(y) d¹(y); x 2 X; (0.1) fÁ(y)·Ã(x)g in Orlicz-Lorentz spaces defined on measure spaces is investigated where the functions Á; Ã; u1; u2; v0 are positive measurable functions. Some sufficient conditions of boundedness of G0 G1 G0 G1;1 T :Λv0 (w0) ! Λv1 (w1) and T :Λv0 (w0) ! Λv1 (w1) are obtained on Orlicz-Lorentz spaces. Furthermore, we achieve sufficient and necessary conditions for T to be bounded and p0 p1;q1 compact from a weighted Lorentz space Λv0 (w0) to another Λv1 (w1). It is notable that the function spaces concerned here are quasi-Banach spaces instead of Banach spaces. Key words : Hardy operator; Orlicz-Lorentz spaces; weighted Lorentz spaces; boundedness; compactness. 2010 Mathematics Subject Classification : 46E30, 46B42. 1. INTRODUCTION R x For the Hardy operator S defined by Sf(x) = 0 f(t)dt, the weighted Lebesgue-norm inequalities have been characterized by many authors (e.g. -
Functional Properties of Hörmander's Space of Distributions Having A
Functional properties of Hörmander’s space of distributions having a specified wavefront set Yoann Dabrowski, Christian Brouder To cite this version: Yoann Dabrowski, Christian Brouder. Functional properties of Hörmander’s space of distributions having a specified wavefront set. 2014. hal-00850192v2 HAL Id: hal-00850192 https://hal.archives-ouvertes.fr/hal-00850192v2 Preprint submitted on 3 May 2014 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Communications in Mathematical Physics manuscript No. (will be inserted by the editor) Functional properties of H¨ormander’s space of distributions having a specified wavefront set Yoann Dabrowski1, Christian Brouder2 1 Institut Camille Jordan UMR 5208, Universit´ede Lyon, Universit´eLyon 1, 43 bd. du 11 novembre 1918, F-69622 Villeurbanne cedex, France 2 Institut de Min´eralogie, de Physique des Mat´eriaux et de Cosmochimie, Sorbonne Univer- sit´es, UMR CNRS 7590, UPMC Univ. Paris 06, Mus´eum National d’Histoire Naturelle, IRD UMR 206, 4 place Jussieu, F-75005 Paris, France. Received: date / Accepted: date ′ Abstract: The space Γ of distributions having their wavefront sets in a closed cone Γ has become importantD in physics because of its role in the formulation of quantum field theory in curved spacetime. -
Generalized Lorentz Spaces and Köthe Duality
Generalized Lorentz spaces and Köthe duality Anna Kaminska´ and Yves Raynaud University of Memphis, Paris University VI Conference on Non Linear Functional Analysis, Universitat Politecnica de Valencia, Spain, 17-20 October 2017 Anna Kaminska´ and Yves Raynaud Generalized Lorentz spaces and Köthe duality µ measure on the the measure space (Ω; A; µ) L0(Ω) = L0(Ω; A; µ) , µ-measurable real valued functions on Ω 0 0 L+(Ω) non-negative functions from L (Ω). L1 = L1(Ω), kf k1, L1 = L1(Ω), kf k1 L1 + L1(Ω), kf kL1+L1(Ω) = inffkgk1 + khk1 : f = g + hg < 1 L1 \ L1(Ω), kf kL1\L1(Ω) = maxfkf k1; kf k1g < 1. A Banach function space E over (Ω; A), is a complete vector space 0 E ⊂ L (Ω) equipped with a norm k · kE such that if 0 ≤ f ≤ g, where 0 g 2 E and f 2 L (Ω), then f 2 E and kf kE ≤ kgkE . The space E satisfies the Fatou property whenever for any 0 f 2 L (Ω), fn 2 E such that fn " f a.e. and sup kfnkE < 1 it follows that f 2 E and kfnkE " kf kE . µ distribution of f with respect to µ, df (s) = µfjf j > sg, s ≥ 0, and its ∗,µ µ decreasing rearrangement f (t) = inffs > 0 : dg (s) ≤ tg, 0 < t < µ(Ω). f ; g are equimeasurable (with respect to the measures µ and ν) if µ ν ∗,µ ∗,ν df (s) = dg (s), s ≥ 0; equivalently, f = g . Anna Kaminska´ and Yves Raynaud Generalized Lorentz spaces and Köthe duality A Banach function space E is symmetric space (with respect to µ) whenever kf kE = kgkE for every µ-equimeasurable functions f ; g 2 E. -
Arxiv:Math/9912098V1 [Math.CA] 13 Dec 1999 Otelrnzspace Lorentz the to H Ouinkresspotdo Uvsi H Ln [0,[7) Hs O These [27])
SHARP LORENTZ SPACE ESTIMATES FOR ROUGH OPERATORS Andreas Seeger and Terence Tao Abstract. We demonstrate the (H1,L1,2) or (Lp,Lp,2) mapping properties of several rough operators. In all cases these estimates are sharp in the sense that the Lorentz exponent 2 cannot be replaced by any lower number. 1. Introduction In this paper we consider the endpoint behaviour on Hardy spaces of two classes of operators, namely singular integral operators with rough homogeneous kernels [4] and singular integral operators with con- volution kernels supported on curves in the plane ([20], [27]). These operators fall outside the Calder´on- Zygmund theory; however weak type (L1,L1,∞) or (H1,L1,∞) inequalities have been established in the previous literature ([7], [9], [16] [18], [25], [29]) We shall show that the target space L1,∞ can be improved to the Lorentz space L1,2, possibly at the cost of moving to a stronger type of Hardy space (e.g. product H1). Examples of Christ [8], [17] show that these types of results are optimal in the sense that one cannot replace L1,2 by L1,q for any q< 2. The space L1,2 arises naturally as the interpolation space halfway between L1,∞ and L1. As a gross caricature of how this space arises, suppose that we have a collection of functions fi which are uniformly bounded in L1, and whose maximal function sup f is in weak L1, and we wish to estimate the quantity i | i| γifi L1,2 Xi 2 for some l co-efficients γi. If the fi are sufficiently orthogonal, we may hope to control this quantity by the square function 2 1/2 (1.1) γifi . -
Topological Vector Spaces, by A
BULLETIN OF THE AMERICAN MATHEMATICAL SOCIETY Volume 82, Number 4, July 1976 BOOK REVIEWS Topological vector spaces, by A. Grothendieck, Gordon and Breach, New York, London, Paris, 1973, x 4- 245 pp., $19.50. (Translated by Orlando Chaljub) This book is a translation of the notes of a course given by Grothendieck in Sao Paulo in 1954 and published in French during the same year (a second edition came out in 1958, a third in 1964). The original lecture notes had several distinctions: they constituted the first expository treatment of locally convex spaces, they contained much material which could not be found anywhere else, and, most importantly, they were written by a man who had become one of the leading mathematicians of the 20th century. Grothendieck was engaged in research on topological vector spaces between 1950 and 1953. During this period he put his stamp on the theory and proved some of its deepest results. In 1954 he wrote his lectures in complete mastery of the whole field as the top expert on the subject: already for this reason alone the notes deserve to appear as a printed book. It begins with a Chapter 0 entitled "Topological introduction" and contain ing preliminary material concerning topics which were less well known in 1954 than they are now: initial and final topologies, precompact sets, topologies in function spaces and equicontinuity. The writing is very concise, and since Chapters I-IV, VIII and IX of Bourbaki's "Topologie générale" are stated to be prerequisites anyway, the reader is advised to study the material in Bourbaki's Chapter X, preferably in the "entirely recast" 1961 edition. -
Arxiv:1811.10987V1 [Math.FA]
FRECHET´ ALGEBRAS IN ABSTRACT HARMONIC ANALYSIS Z. ALIMOHAMMADI AND A. REJALI Abstract. We provide a survey of the similarities and differences between Banach and Fr´echet algebras including some known results and examples. We also collect some important generalizations in abstract harmonic anal- ysis; for example, the generalization of the concepts of vector-valued Lips- chitz algebras, abstract Segal algebras, Arens regularity, amenability, weak amenability, ideal amenability, etc. 0. Introduction The class of Fr´echet algebras which is an important class of locally convex algebras has been widely studied by many authors. For a full understanding of Fr´echet algebras, one may refer to [27, 36]. In the class of Banach algebras, there are many concepts which were generalized to the Fr´echet case. Examples of these concepts are as follows. Biprojective Banach algebras were studied by several authors, notably A. Ya. Helemskii [35] and Yu. V. Selivanov [62]. A number of papers appeared in the literature concerned with extending the notion of biprojectivity and its results to the Fr´echet algebras; see for example [48, 63]. Flat cyclic Fr´echet modules were investigated by A. Yu. Pirkovskii [49]. Let A be a Fr´echet algebra and I be a closed left ideal in A. Pirkovskii showed that there exists a necessary and sufficient condition for a cyclic Fr´echet A-module A♯/I to be strictly flat. He also generalized a number of characterizations of amenable Ba- nach algebras to the Fr´echet algebras (ibid.). In 2008, P. Lawson and C. J. Read [43] introduced and studied the notions of approximate amenability and approxi- mate contractibility of Fr´echet algebras. -
Upper Estimates for Gâteaux Differentiability of Bump Functions in Orlicz-Lorentz Spaces
Volume 8 (2007), Issue 4, Article 113, 8 pp. UPPER ESTIMATES FOR GÂTEAUX DIFFERENTIABILITY OF BUMP FUNCTIONS IN ORLICZ-LORENTZ SPACES B. ZLATANOV DEPARTMENT OF MATHEMATICS AND INFORMATICS PLOVDIV UNIVERSITY, 24 “TZAR ASSEN” STR. PLOVDIV, 4000 BULGARIA [email protected] Received 29 January, 2007; accepted 17 November, 2007 Communicated by C.P. Niculescu ABSTRACT. Upper estimates for the order of Gâteaux smoothness of bump functions in Orlicz– Lorentz spaces d(w, M, Γ), Γ uncountable, are obtained. The best possible order of Gâteaux differentiability in the class of all equivalent norms in d(w, M, Γ) is found. Key words and phrases: Orlicz function, Orlicz–Lorentz space, Smooth bump functions. 2000 Mathematics Subject Classification. 46B25, 40E30. 1. INTRODUCTION The existence of higher order Fréchet smooth norms and bump functions and its impact on the geometrical properties of a Banach space have been subject to many investigations begin- ning with the classical result for Lp–spaces in [1] and [6]. An extensive study and bibliography may be found in [2]. As any negative result on the existence of Gâteaux smooth bump func- tions immediately applies to the problem of existence of Fréchet smooth bump functions and norms, the question arises of estimating the best possible order of Gâteaux smoothness of bump functions in a given Banach space. A variational technique (the Ekeland variational principle) was applied in [2] to show that in `1(Γ), Γ uncountable, there is no continuous Gâteaux dif- ferentiable bump function. Following the same idea and using Stegall’s variational principle, an extension of this result to Banach spaces with uncountable unconditional basis was given in [4] and to Banach spaces with uncountable symmetric basis in [9].