ON SEMI-BARRELLED SPACES Henri Bourlès
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On Quasi Norm Attaining Operators Between Banach Spaces
ON QUASI NORM ATTAINING OPERATORS BETWEEN BANACH SPACES GEUNSU CHOI, YUN SUNG CHOI, MINGU JUNG, AND MIGUEL MART´IN Abstract. We provide a characterization of the Radon-Nikod´ymproperty in terms of the denseness of bounded linear operators which attain their norm in a weak sense, which complement the one given by Bourgain and Huff in the 1970's. To this end, we introduce the following notion: an operator T : X ÝÑ Y between the Banach spaces X and Y is quasi norm attaining if there is a sequence pxnq of norm one elements in X such that pT xnq converges to some u P Y with }u}“}T }. Norm attaining operators in the usual (or strong) sense (i.e. operators for which there is a point in the unit ball where the norm of its image equals the norm of the operator) and also compact operators satisfy this definition. We prove that strong Radon-Nikod´ymoperators can be approximated by quasi norm attaining operators, a result which does not hold for norm attaining operators in the strong sense. This shows that this new notion of quasi norm attainment allows to characterize the Radon-Nikod´ymproperty in terms of denseness of quasi norm attaining operators for both domain and range spaces, completing thus a characterization by Bourgain and Huff in terms of norm attaining operators which is only valid for domain spaces and it is actually false for range spaces (due to a celebrated example by Gowers of 1990). A number of other related results are also included in the paper: we give some positive results on the denseness of norm attaining Lipschitz maps, norm attaining multilinear maps and norm attaining polynomials, characterize both finite dimensionality and reflexivity in terms of quasi norm attaining operators, discuss conditions to obtain that quasi norm attaining operators are actually norm attaining, study the relationship with the norm attainment of the adjoint operator and, finally, present some stability results. -
Quantitative Hahn-Banach Theorems and Isometric Extensions for Wavelet and Other Banach Spaces
Axioms 2013, 2, 224-270; doi:10.3390/axioms2020224 OPEN ACCESS axioms ISSN 2075-1680 www.mdpi.com/journal/axioms Article Quantitative Hahn-Banach Theorems and Isometric Extensions for Wavelet and Other Banach Spaces Sergey Ajiev School of Mathematical Sciences, Faculty of Science, University of Technology-Sydney, P.O. Box 123, Broadway, NSW 2007, Australia; E-Mail: [email protected] Received: 4 March 2013; in revised form: 12 May 2013 / Accepted: 14 May 2013 / Published: 23 May 2013 Abstract: We introduce and study Clarkson, Dol’nikov-Pichugov, Jacobi and mutual diameter constants reflecting the geometry of a Banach space and Clarkson, Jacobi and Pichugov classes of Banach spaces and their relations with James, self-Jung, Kottman and Schaffer¨ constants in order to establish quantitative versions of Hahn-Banach separability theorem and to characterise the isometric extendability of Holder-Lipschitz¨ mappings. Abstract results are further applied to the spaces and pairs from the wide classes IG and IG+ and non-commutative Lp-spaces. The intimate relation between the subspaces and quotients of the IG-spaces on one side and various types of anisotropic Besov, Lizorkin-Triebel and Sobolev spaces of functions on open subsets of an Euclidean space defined in terms of differences, local polynomial approximations, wavelet decompositions and other means (as well as the duals and the lp-sums of all these spaces) on the other side, allows us to present the algorithm of extending the main results of the article to the latter spaces and pairs. Special attention is paid to the matter of sharpness. Our approach is quasi-Euclidean in its nature because it relies on the extrapolation of properties of Hilbert spaces and the study of 1-complemented subspaces of the spaces under consideration. -
Proximal Analysis and Boundaries of Closed Sets in Banach Space, Part I: Theory
Can. J. Math., Vol. XXXVIII, No. 2, 1986, pp. 431-452 PROXIMAL ANALYSIS AND BOUNDARIES OF CLOSED SETS IN BANACH SPACE, PART I: THEORY J. M. BORWEIN AND H. M. STROJWAS 0. Introduction. As various types of tangent cones, generalized deriva tives and subgradients prove to be a useful tool in nonsmooth optimization and nonsmooth analysis, we witness a considerable interest in analysis of their properties, relations and applications. Recently, Treiman [18] proved that the Clarke tangent cone at a point to a closed subset of a Banach space contains the limit inferior of the contingent cones to the set at neighbouring points. We provide a considerable strengthening of this result for reflexive spaces. Exploring the analogous inclusion in which the contingent cones are replaced by pseudocontingent cones we have observed that it does not hold any longer in a general Banach space, however it does in reflexive spaces. Among the several basic relations we have discovered is the following one: the Clarke tangent cone at a point to a closed subset of a reflexive Banach space is equal to the limit inferior of the weak (pseudo) contingent cones to the set at neighbouring points. This generalizes the results of Penot [14] and Cornet [7] for finite dimensional spaces and of Penot [14] for reflexive spaces. What is more we show that this equality characterizes reflex ive spaces among Banach spaces, similarly as the analogous equality with the contingent cones instead of the weak contingent cones, characterizes finite dimensional spaces among Banach spaces. We also present several other related characterizations of reflexive spaces and variants of the considered inclusions for boundedly relatively weakly compact sets. -
Approximation Boundedness Surjectivity
APPROXIMATION BOUNDEDNESS SURJECTIVITY Olav Kristian Nygaard Dr. scient. thesis, University of Bergen, 2001 Approximation, Boundedness, Surjectivity Olav Kr. Nygaard, 2001 ISBN 82-92-160-08-6 Contents 1Theframework 9 1.1 Separability, bases and the approximation property ....... 13 1.2Thecompletenessassumption................... 16 1.3Theoryofclosed,convexsets................... 19 2 Factorization of weakly compact operators and the approximation property 25 2.1Introduction............................. 25 2.2 Criteria of the approximation property in terms of the Davis- Figiel-Johnson-Pe'lczy´nskifactorization.............. 27 2.3Uniformisometricfactorization.................. 33 2.4 The approximation property and ideals of finite rank operators 36 2.5 The compact approximation property and ideals of compact operators.............................. 39 2.6 From approximation properties to metric approximation prop- erties................................. 41 3 Boundedness and surjectivity 49 3.1Introduction............................. 49 3.2Somemorepreliminaries...................... 52 3.3 The boundedness property in normed spaces . ....... 57 3.4ThesurjectivitypropertyinBanachspaces........... 59 3.5 The Seever property and the Nikod´ymproperty......... 63 3.6 Some results on thickness in L(X, Y )∗ .............. 63 3.7Somequestionsandremarks.................... 65 4 Slices in the unit ball of a uniform algebra 69 4.1Introduction............................. 69 4.2Thesliceshavediameter2..................... 70 4.3Someremarks........................... -
Convenient Vector Spaces, Convenient Manifolds and Differential Linear Logic
Convenient Vector Spaces, Convenient Manifolds and Differential Linear Logic Richard Blute University of Ottawa ongoing discussions with Geoff Crutwell, Thomas Ehrhard, Alex Hoffnung, Christine Tasson June 20, 2011 Richard Blute Convenient Vector Spaces, Convenient Manifolds and Differential Linear Logic Goals Develop a theory of (smooth) manifolds based on differential linear logic. Or perhaps develop a differential linear logic based on manifolds. Convenient vector spaces were recently shown to be a model. There is a well-developed theory of convenient manifolds, including infinite-dimensional manifolds. Convenient manifolds reveal additional structure not seen in finite dimensions. In particular, the notion of tangent space is much more complex. Synthetic differential geometry should also provide information. Convenient vector spaces embed into an extremely good model. Richard Blute Convenient Vector Spaces, Convenient Manifolds and Differential Linear Logic Convenient vector spaces (Fr¨olicher,Kriegl) Definition A vector space is locally convex if it is equipped with a topology such that each point has a neighborhood basis of convex sets, and addition and scalar multiplication are continuous. Locally convex spaces are the most well-behaved topological vector spaces, and most studied in functional analysis. Note that in any topological vector space, one can take limits and hence talk about derivatives of curves. A curve is smooth if it has derivatives of all orders. The analogue of Cauchy sequences in locally convex spaces are called Mackey-Cauchy sequences. The convergence of Mackey-Cauchy sequences implies the convergence of all Mackey-Cauchy nets. The following is taken from a long list of equivalences. Richard Blute Convenient Vector Spaces, Convenient Manifolds and Differential Linear Logic Convenient vector spaces II: Definition Theorem Let E be a locally convex vector space. -
International Centre for Theoretical Physics
zrrl^^^'C^z ic/89/30i INTERNATIONAL CENTRE FOR THEORETICAL PHYSICS ON THE APPROXIMATIVE NORMAL VALUES OF MULTIVALUES OPERATORS IN TOPOLOGICAL VECTOR SPACE Nguyen Minh Chuong and INTERNATIONAL ATOMIC ENERGY Khuat van Ninh AGENCY UNITED NATIONS EDUCATIONAL, SCIENTIFIC AND CULTURAL ORGANIZATION IC/89/301 SUNTO International Atomic Energy Agency and In questo articolo si considera il problemadell'approssimaztone di valori normali di oper- United Nations Educational Scientific and Cultural Organization atori chiusi lineari multivoci dallo spazio vettoriale topologico de Mackey, a valori in un E-spazio. INTERNATIONAL CENTRE FOR THEORETICAL PHYSICS Si dimostrano l'esistenza di un valore normale e la convergenza dei valori approssimanti il valore normale. ON THE APPROXIMATIVE NORMAL VALUES OF MULTIVALUED OPERATORS IN TOPOLOGICAL VECTOR SPACE * Nguyen Minn Chuong * International Centre for Theoretical Physics, Trieste, Italy. and Khuat van Ninh Department of Numerical Analysis, Institute of Mathematics, P.O. Box 631, Bo Ho, 10 000 Hanoi, Vietnam. ABSTRACT In this paper the problem of approximation of normal values of multivalued linear closed operators from topological vector Mackey space into E-space is considered. Existence of normal value and covergence of approximative values to normal value are proved. MIRAMARE - TRIESTE September 1989 To be submitted for publication. Permanent address: Department of Numerical Analysis, Institute of Mathematics, P.O. Box 631, Bo Ho 10 000 Hanoi, Vietnam. 1. Introduction Let X , Y be closed Eubspaces of X,Y respectively, where X is normed In recent years problems on normal value and on approximation of space and Y is Hackey space. Let T be a linear multivalued operator from normal value of multivalued linear operators have been investigated Y to X . -
Uniqueness of Von Neumann Bornology in Locally C∗-Algebras
Scientiae Mathematicae Japonicae Online, e-2009 91 UNIQUENESS OF VON NEUMANN BORNOLOGY IN LOCALLY C∗-ALGEBRAS. A BORNOLOGICAL ANALOGUE OF JOHNSON’S THEOREM M. Oudadess Received May 31, 2008; revised March 20, 2009 Abstract. All locally C∗- structures on a commutative complex algebra have the same bound structure. It is also shown that a Mackey complete C∗-convex algebra is semisimple. By the well-known Johnson’s theorem [4], there is on a given complex semi-simple algebra a unique (up to an isomorphism) Banach algebra norm. R. C. Carpenter extended this result to commutative Fr´echet locally m-convex algebras [3]. Without metrizability, it is not any more valid even in the rich context of locally C∗-convex algebras. Below there are given telling examples where even a C∗-algebra structure is involved. We follow the terminology of [5], pp. 101-102. Let E be an involutive algebra and p a vector space seminorm on E. We say that p is a C∗-seminorm if p(x∗x)=[p(x)]2, for every x. An involutive topological algebra whose topology is defined by a (saturated) family of C∗-seminorms is called a C∗-convex algebra. A complete C∗-convex algebra is called a locally C∗-algebra (by Inoue). A Fr´echet C∗-convex algebra is a metrizable C∗- convex algebra, that is equivalently a metrizable locally C∗-algebra, or also a Fr´echet locally C∗-algebra. All the bornological notions can be found in [6]. The references for m-convexity are [5], [8] and [9]. Let us recall for convenience that the bounded structure (bornology) of a locally convex algebra (l.c.a.)(E,τ) is the collection Bτ of all the subsets B of E which are bounded in the sense of Kolmogorov and von Neumann, that is B is absorbed by every neighborhood of the origin (see e.g. -
Arxiv:1702.07867V1 [Math.FA]
TOPOLOGICAL PROPERTIES OF STRICT (LF )-SPACES AND STRONG DUALS OF MONTEL STRICT (LF )-SPACES SAAK GABRIYELYAN Abstract. Following [2], a Tychonoff space X is Ascoli if every compact subset of Ck(X) is equicontinuous. By the classical Ascoli theorem every k- space is Ascoli. We show that a strict (LF )-space E is Ascoli iff E is a Fr´echet ′ space or E = ϕ. We prove that the strong dual Eβ of a Montel strict (LF )- space E is an Ascoli space iff one of the following assertions holds: (i) E is a ′ Fr´echet–Montel space, so Eβ is a sequential non-Fr´echet–Urysohn space, or (ii) ′ ω D E = ϕ, so Eβ = R . Consequently, the space (Ω) of test functions and the space of distributions D′(Ω) are not Ascoli that strengthens results of Shirai [20] and Dudley [5], respectively. 1. Introduction. The class of strict (LF )-spaces was intensively studied in the classic paper of Dieudonn´eand Schwartz [3]. It turns out that many of strict (LF )-spaces, in particular a lot of linear spaces considered in Schwartz’s theory of distributions [18], are not metrizable. Even the simplest ℵ0-dimensional strict (LF )-space ϕ, n the inductive limit of the sequence {R }n∈ω, is not metrizable. Nyikos [16] showed that ϕ is a sequential non-Fr´echet–Urysohn space (all relevant definitions are given in the next section). On the other hand, Shirai [20] proved the space D(Ω) of test functions over an open subset Ω of Rn, which is one of the most famous example of strict (LF )-spaces, is not sequential. -
Polar Convolution∗
SIAM J. OPTIM. c 2019 Society for Industrial and Applied Mathematics Vol. 29, No. 2, pp. 1366{1391 POLAR CONVOLUTION∗ MICHAEL P. FRIEDLANDERy , IVES MACEDO^ z , AND TING KEI PONGx Abstract. The Moreau envelope is one of the key convexity-preserving functional operations in convex analysis, and it is central to the development and analysis of many approaches for convex optimization. This paper develops the theory for an analogous convolution operation, called the polar envelope, specialized to gauge functions. Many important properties of the Moreau envelope and the proximal map are mirrored by the polar envelope and its corresponding proximal map. These properties include smoothness of the envelope function, uniqueness, and continuity of the proximal map, which play important roles in duality and in the construction of algorithms for gauge optimization. A suite of tools with which to build algorithms for this family of optimization problems is thus established. Key words. gauge optimization, max convolution, proximal algorithms AMS subject classifications. 90C15, 90C25 DOI. 10.1137/18M1209088 1. Motivation. Let f1 and f2 be proper convex functions that map a finite- dimensional Euclidean space X to the extended reals R [ f+1g. The infimal sum convolution operation (1.1) (f1 f2)(x) = inf f f1(z) + f2(x − z) g z results in a convex function that is a \mixture" of f1 and f2. As is usually the case in convex analysis, the operation is best understood from the epigraphical viewpoint: if the infimal operation attains its optimal value at each x, then the resulting function f1 f2 satisfies the relationship epi(f1 f2) = epi f1 + epi f2: Sum convolution is thus also known as epigraphical addition [14, Page 34]. -
Nonlinear Programming and Optimal Control
.f i ! NASA CQNTRACTQR REPORT o* h d I e U NONLINEAR PROGRAMMING AND OPTIMAL CONTROL Prepared under Grant No. NsG-354 by UNIVERSITY OF CALIFORNIA Berkeley, Calif. for ,:, NATIONALAERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. 0 MAY 1966 TECH LIBRARY KAFB, NY NONLINEAR PROGRAMING AND OPTIMAL CONTROL By Pravin P. Varaiya Distribution of this report is provided in the interest of informationexchange. Responsibility for the contents resides in the author or organization that prepared it. Prepared under Grant No. NsG-354 by UNIVERSITY OF CALIFORNIA Berkeley, Calif. for NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - Price $3.00 I NONLINEAR PROGRAMMING AND OPTIMAL CONTROL Pravin Pratap Varaiya ABSTRACT Considerable effort has been devoted in recent years to three classes of optimization problems. These areas are non- linear programming, optimal control, and solution of large-scale systems via decomposition. We have proposed a model problem which is a generalization of the usual nonlinear programming pro- blem, and which subsumes these three classes. We derive nec- essary conditions for the solution of our problem. These condi- tions, under varying interpretations and assumptions, yield the Kuhn-Tucker theorem and the maximum principle. Furthermore, they enable us to devise decomposition techniques for a class of large convex programming problems. More important than this unification, in our opinion, is the fact that we have been able to develop a point of view which is useful for most optimization problems. Specifically, weshow that there exist sets which we call local cones and local polars (Chapter I), which play a determining role in maximization theories which consider only first variations, and that these theories give varying sets of assumptions under which these sets, or relations between them, can be obtained explicitly. -
S-Barrelled Topological Vector Spaces*
Canad. Math. Bull. Vol. 21 (2), 1978 S-BARRELLED TOPOLOGICAL VECTOR SPACES* BY RAY F. SNIPES N. Bourbaki [1] was the first to introduce the class of locally convex topological vector spaces called "espaces tonnelés" or "barrelled spaces." These spaces have some of the important properties of Banach spaces and Fréchet spaces. Indeed, a generalized Banach-Steinhaus theorem is valid for them, although barrelled spaces are not necessarily metrizable. Extensive accounts of the properties of barrelled locally convex topological vector spaces are found in [5] and [8]. In the last few years, many new classes of locally convex spaces having various types of barrelledness properties have been defined (see [6] and [7]). In this paper, using simple notions of sequential convergence, we introduce several new classes of topological vector spaces which are similar to Bourbaki's barrelled spaces. The most important of these we call S-barrelled topological vector spaces. A topological vector space (X, 2P) is S-barrelled if every sequen tially closed, convex, balanced, and absorbing subset of X is a sequential neighborhood of the zero vector 0 in X Examples are given of spaces which are S-barrelled but not barrelled. Then some of the properties of S-barrelled spaces are given—including permanence properties, and a form of the Banach- Steinhaus theorem valid for them. S-barrelled spaces are useful in the study of sequentially continuous linear transformations and sequentially continuous bilinear functions. For the most part, we use the notations and definitions of [5]. Proofs which closely follow the standard patterns are omitted. 1. Definitions and Examples. -
Topologies on the Test Function Algebra Publications Du Département De Mathématiques De Lyon, 1975, Tome 12, Fascicule 1 , P
PUBLICATIONS DU DÉPARTEMENT DE MATHÉMATIQUES DE LYON G. LASSNER O∗-Topologies on the Test Function Algebra Publications du Département de Mathématiques de Lyon, 1975, tome 12, fascicule 1 , p. 25-38 <http://www.numdam.org/item?id=PDML_1975__12_1_25_0> © Université de Lyon, 1975, tous droits réservés. L’accès aux archives de la série « Publications du Département de mathématiques de Lyon » im- plique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pé- nale. 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/ Publications du Dlpartement de Math6matiques Lyon 1975 t.12.1 0*-TOPOLOGIES ON THE TEST FUNCTION ALGEBRA G. LASSNER 1. INTRODUCTION This paper deals with C*-like topologies on the test function algebra ?l » the tensor algebra over the Schwartz space [S . These topologies are connected with continuous representations of this algebra. If R is a *-algebra and 8s a pre-Hilbert space, then a representation a A(a) of R in if is a homomorphism of R into End £ , such that <$fA(a)lf>> « <A(a*)<frfiJ;> for all $ ^ e 3) . For a representation of a Banach *-algebra R all operators A(a) are automatically bounded and the representation is uniformly continuous. In fact, for 4>c® , f(a) = <<f>,A(a)<J» is a positive functional on R and therefore [ l] : ||A(aH|| = «t>,A(a*a)<j?> = f(a*a) * f<l)||a<a|| «N«H|2 l|a||2 , 25 O* -topologies on the test function algebra which implies j !A(a)| U||a|| .