Real Analysis: Part II
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Duality for Outer $ L^ P \Mu (\Ell^ R) $ Spaces and Relation to Tent Spaces
p r DUALITY FOR OUTER Lµpℓ q SPACES AND RELATION TO TENT SPACES MARCO FRACCAROLI p r Abstract. We prove that the outer Lµpℓ q spaces, introduced by Do and Thiele, are isomorphic to Banach spaces, and we show the expected duality properties between them for 1 ă p ď8, 1 ď r ă8 or p “ r P t1, 8u uniformly in the finite setting. In the case p “ 1, 1 ă r ď8, we exhibit a counterexample to uniformity. We show that in the upper half space setting these properties hold true in the full range 1 ď p,r ď8. These results are obtained via greedy p r decompositions of functions in Lµpℓ q. As a consequence, we establish the p p r equivalence between the classical tent spaces Tr and the outer Lµpℓ q spaces in the upper half space. Finally, we give a full classification of weak and strong type estimates for a class of embedding maps to the upper half space with a fractional scale factor for functions on Rd. 1. Introduction The Lp theory for outer measure spaces discussed in [13] generalizes the classical product, or iteration, of weighted Lp quasi-norms. Since we are mainly interested in positive objects, we assume every function to be nonnegative unless explicitly stated. We first focus on the finite setting. On the Cartesian product X of two finite sets equipped with strictly positive weights pY,µq, pZ,νq, we can define the classical product, or iterated, L8Lr,LpLr spaces for 0 ă p, r ă8 by the quasi-norms 1 r r kfkL8ppY,µq,LrpZ,νqq “ supp νpzqfpy,zq q yPY zÿPZ ´1 r 1 “ suppµpyq ωpy,zqfpy,zq q r , yPY zÿPZ p 1 r r p kfkLpppY,µq,LrpZ,νqq “ p µpyqp νpzqfpy,zq q q , arXiv:2001.05903v1 [math.CA] 16 Jan 2020 yÿPY zÿPZ where we denote by ω “ µ b ν the induced weight on X. -
ON SEQUENCE SPACES DEFINED by the DOMAIN of TRIBONACCI MATRIX in C0 and C Taja Yaying and Merve ˙Ilkhan Kara 1. Introduction Th
Korean J. Math. 29 (2021), No. 1, pp. 25{40 http://dx.doi.org/10.11568/kjm.2021.29.1.25 ON SEQUENCE SPACES DEFINED BY THE DOMAIN OF TRIBONACCI MATRIX IN c0 AND c Taja Yaying∗;y and Merve Ilkhan_ Kara Abstract. In this article we introduce tribonacci sequence spaces c0(T ) and c(T ) derived by the domain of a newly defined regular tribonacci matrix T: We give some topological properties, inclusion relations, obtain the Schauder basis and determine α−; β− and γ− duals of the spaces c0(T ) and c(T ): We characterize certain matrix classes (c0(T );Y ) and (c(T );Y ); where Y is any of the spaces c0; c or `1: Finally, using Hausdorff measure of non-compactness we characterize certain class of compact operators on the space c0(T ): 1. Introduction Throughout the paper N = f0; 1; 2; 3;:::g and w is the space of all real valued sequences. By `1; c0 and c; we mean the spaces all bounded, null and convergent sequences, respectively. Also by `p; cs; cs0 and bs; we mean the spaces of absolutely p-summable, convergent, null and bounded series, respectively, where 1 ≤ p < 1: We write φ for the space of all sequences that terminate in zero. Moreover, we denote the space of all sequences of bounded variation by bv: A Banach space X is said to be a BK-space if it has continuous coordinates. The spaces `1; c0 and c are BK- spaces with norm kxk = sup jx j : Here and henceforth, for simplicity in notation, `1 k k the summation without limit runs from 0 to 1: Also, we shall use the notation e = (1; 1; 1;:::) and e(k) to be the sequence whose only non-zero term is 1 in the kth place for each k 2 N: Let X and Y be two sequence spaces and let A = (ank) be an infinite matrix of real th entries. -
Chapter 4 the Lebesgue Spaces
Chapter 4 The Lebesgue Spaces In this chapter we study Lp-integrable functions as a function space. Knowledge on functional analysis required for our study is briefly reviewed in the first two sections. In Section 1 the notions of normed and inner product spaces and their properties such as completeness, separability, the Heine-Borel property and espe- cially the so-called projection property are discussed. Section 2 is concerned with bounded linear functionals and the dual space of a normed space. The Lp-space is introduced in Section 3, where its completeness and various density assertions by simple or continuous functions are covered. The dual space of the Lp-space is determined in Section 4 where the key notion of uniform convexity is introduced and established for the Lp-spaces. Finally, we study strong and weak conver- gence of Lp-sequences respectively in Sections 5 and 6. Both are important for applications. 4.1 Normed Spaces In this and the next section we review essential elements of functional analysis that are relevant to our study of the Lp-spaces. You may look up any book on functional analysis or my notes on this subject attached in this webpage. Let X be a vector space over R. A norm on X is a map from X ! [0; 1) satisfying the following three \axioms": For 8x; y; z 2 X, (i) kxk ≥ 0 and is equal to 0 if and only if x = 0; (ii) kαxk = jαj kxk, 8α 2 R; and (iii) kx + yk ≤ kxk + kyk. The pair (X; k·k) is called a normed vector space or normed space for short. -
Functional Analysis Lecture Notes Chapter 3. Banach
FUNCTIONAL ANALYSIS LECTURE NOTES CHAPTER 3. BANACH SPACES CHRISTOPHER HEIL 1. Elementary Properties and Examples Notation 1.1. Throughout, F will denote either the real line R or the complex plane C. All vector spaces are assumed to be over the field F. Definition 1.2. Let X be a vector space over the field F. Then a semi-norm on X is a function k · k: X ! R such that (a) kxk ≥ 0 for all x 2 X, (b) kαxk = jαj kxk for all x 2 X and α 2 F, (c) Triangle Inequality: kx + yk ≤ kxk + kyk for all x, y 2 X. A norm on X is a semi-norm which also satisfies: (d) kxk = 0 =) x = 0. A vector space X together with a norm k · k is called a normed linear space, a normed vector space, or simply a normed space. Definition 1.3. Let I be a finite or countable index set (for example, I = f1; : : : ; Ng if finite, or I = N or Z if infinite). Let w : I ! [0; 1). Given a sequence of scalars x = (xi)i2I , set 1=p jx jp w(i)p ; 0 < p < 1; 8 i kxkp;w = > Xi2I <> sup jxij w(i); p = 1; i2I > where these quantities could be infinite.:> Then we set p `w(I) = x = (xi)i2I : kxkp < 1 : n o p p p We call `w(I) a weighted ` space, and often denote it just by `w (especially if I = N). If p p w(i) = 1 for all i, then we simply call this space ` (I) or ` and write k · kp instead of k · kp;w. -
LEBESGUE MEASURE and L2 SPACE. Contents 1. Measure Spaces 1 2. Lebesgue Integration 2 3. L2 Space 4 Acknowledgments 9 References
LEBESGUE MEASURE AND L2 SPACE. ANNIE WANG Abstract. This paper begins with an introduction to measure spaces and the Lebesgue theory of measure and integration. Several important theorems regarding the Lebesgue integral are then developed. Finally, we prove the completeness of the L2(µ) space and show that it is a metric space, and a Hilbert space. Contents 1. Measure Spaces 1 2. Lebesgue Integration 2 3. L2 Space 4 Acknowledgments 9 References 9 1. Measure Spaces Definition 1.1. Suppose X is a set. Then X is said to be a measure space if there exists a σ-ring M (that is, M is a nonempty family of subsets of X closed under countable unions and under complements)of subsets of X and a non-negative countably additive set function µ (called a measure) defined on M . If X 2 M, then X is said to be a measurable space. For example, let X = Rp, M the collection of Lebesgue-measurable subsets of Rp, and µ the Lebesgue measure. Another measure space can be found by taking X to be the set of all positive integers, M the collection of all subsets of X, and µ(E) the number of elements of E. We will be interested only in a special case of the measure, the Lebesgue measure. The Lebesgue measure allows us to extend the notions of length and volume to more complicated sets. Definition 1.2. Let Rp be a p-dimensional Euclidean space . We denote an interval p of R by the set of points x = (x1; :::; xp) such that (1.3) ai ≤ xi ≤ bi (i = 1; : : : ; p) Definition 1.4. -
Linear Spaces
Chapter 2 Linear Spaces Contents FieldofScalars ........................................ ............. 2.2 VectorSpaces ........................................ .............. 2.3 Subspaces .......................................... .............. 2.5 Sumofsubsets........................................ .............. 2.5 Linearcombinations..................................... .............. 2.6 Linearindependence................................... ................ 2.7 BasisandDimension ..................................... ............. 2.7 Convexity ............................................ ............ 2.8 Normedlinearspaces ................................... ............... 2.9 The `p and Lp spaces ............................................. 2.10 Topologicalconcepts ................................... ............... 2.12 Opensets ............................................ ............ 2.13 Closedsets........................................... ............. 2.14 Boundedsets......................................... .............. 2.15 Convergence of sequences . ................... 2.16 Series .............................................. ............ 2.17 Cauchysequences .................................... ................ 2.18 Banachspaces....................................... ............... 2.19 Completesubsets ....................................... ............. 2.19 Transformations ...................................... ............... 2.21 Lineartransformations.................................. ................ 2.21 -
U. Green's Functions
Theoretical Physics Prof. Ruiz, UNC Asheville, doctorphys on YouTube Chapter U Notes. Green's Functions U1. Impulse Response. We return to our low-pass filter with R 1 , C 1 , and ft( ) 1 for 1 second from t 0 to t 1 . The initial charge on the capacitor is q(0) 0 . We have already solved this problem. The charge on the capacitor is given by the following integral. t q()()() t f u g t u du 0 This solution is the convolution of our input voltage function ft() t and the capacitor-decay response function g() t e . The input function is for us to choose, but the capacitor response function is intrinsic to our low-pass filter. q dq f() t V IR I q q Our differential equation is C dt . The Laplace transform gives F()()() s sQ s Q s 1 Q()()()() s F s F s G s s 1 We know from before that a product in Laplace-transform s-space means a convolution of the respective functions in our t-space. The s-space shows clearly the separation of our input function and the response function. All of the secrets of the system are in Gs(). What is the formal way to solve for this without the Fs() getting in the way? Well, if you set ft( ) 0 , that kills things because the Laplace transform of zero is 1 Q() s (0) (0)() G s 0 zero and you would get . s 1 Michael J. Ruiz, Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License So we really want Q() s F ()() s G s (1)() G s G () s in order to get to know the system for itself. -
Multiplication and Composition Operators on Weak Lp Spaces
Multiplication and Composition Operators on Weak Lp spaces Ren´eErlin Castillo1, Fabio Andr´esVallejo Narvaez2 and Julio C. Ramos Fern´andez3 Abstract In a self-contained presentation, we discuss the Weak Lp spaces. Invertible and compact multiplication operators on Weak Lp are char- acterized. Boundedness of the composition operator on Weak Lp is also characterized. Keywords: Compact operator, multiplication and composition oper- ator, distribution function, Weak Lp spaces. Contents 1 Introduction 2 2 Weak Lp spaces 2 3 Convergence in measure 7 4 An interpolation result 13 5 Normability of Weak Lp for p > 1 25 6 Multiplication Operators 39 7 Composition Operator 49 A Appendix 52 02010 Mathematics subjects classification primary 47B33, 47B38; secondary 46E30 1 1 Introduction One of the real attraction of Weak Lp space is that the subject is sufficiently concrete and yet the spaces have fine structure of importance for applications. WeakLp spaces are function spaces which are closely related to Lp spaces. We do not know the exact origin of Weak Lp spaces, which is a apparently part of the folklore. The Book by Colin Benett and Robert Sharpley[4] contains a good presentation of Weak Lp but from the point of view of rearrangement function. In the present paper we study the Weak Lp space from the point of view of distribution function. This circumstance motivated us to undertake a preparation of the present paper containing a detailed exposition of these function spaces. In section 6 of the present paper we first prove a charac- terization of the boundedness of Mu in terms of u, and show that the set of multiplication operators on Weak Lp is a maximal abelian subalgebra of B WeakLp , the Banach algebra of all bounded linear operators on WeakLp. -
Normed and Banach Spaces 9 1
Funtional Analysis Lecture notes for 18.102 Richard Melrose Department of Mathematics, MIT E-mail address: [email protected] Version 0.8D; Revised: 4-5-2010; Run: February 4, 2014 . Contents Preface 5 Introduction 6 Chapter 1. Normed and Banach spaces 9 1. Vector spaces 9 2. Normed spaces 11 3. Banach spaces 13 4. Operators and functionals 16 5. Subspaces and quotients 19 6. Completion 20 7. More examples 24 8. Baire's theorem 26 9. Uniform boundedness 27 10. Open mapping theorem 28 11. Closed graph theorem 30 12. Hahn-Banach theorem 30 13. Double dual 34 14. Axioms of a vector space 34 Chapter 2. The Lebesgue integral 35 1. Integrable functions 35 2. Linearity of L1 39 3. The integral on L1 41 4. Summable series in L1(R) 45 5. The space L1(R) 47 6. The three integration theorems 48 7. Notions of convergence 51 8. Measurable functions 51 9. The spaces Lp(R) 52 10. The space L2(R) 53 11. The spaces Lp(R) 55 12. Lebesgue measure 58 13. Density of step functions 59 14. Measures on the line 61 15. Higher dimensions 62 Removed material 64 Chapter 3. Hilbert spaces 67 1. pre-Hilbert spaces 67 2. Hilbert spaces 68 3 4 CONTENTS 3. Orthonormal sets 69 4. Gram-Schmidt procedure 69 5. Complete orthonormal bases 70 6. Isomorphism to l2 71 7. Parallelogram law 72 8. Convex sets and length minimizer 72 9. Orthocomplements and projections 73 10. Riesz' theorem 74 11. Adjoints of bounded operators 75 12. -
A First Course in Topology: Explaining Continuity (For Math 112, Spring 2005)
A FIRST COURSE IN TOPOLOGY: EXPLAINING CONTINUITY (FOR MATH 112, SPRING 2005) PAUL BANKSTON CONTENTS (1) Epsilons and Deltas ................................... .................2 (2) Distance Functions in Euclidean Space . .....7 (3) Metrics and Metric Spaces . ..........10 (4) Some Topology of Metric Spaces . ..........15 (5) Topologies and Topological Spaces . ...........21 (6) Comparison of Topologies on a Set . ............27 (7) Bases and Subbases for Topologies . .........31 (8) Homeomorphisms and Topological Properties . ........39 (9) The Basic Lower-Level Separation Axioms . .......46 (10) Convergence ........................................ ..................52 (11) Connectedness . ..............60 (12) Path Connectedness . ............68 (13) Compactness ........................................ .................71 (14) Product Spaces . ..............78 (15) Quotient Spaces . ..............82 (16) The Basic Upper-Level Separation Axioms . .......86 (17) Some Countability Conditions . .............92 1 2 PAUL BANKSTON (18) Further Reading . ...............97 TOPOLOGY 3 1. Epsilons and Deltas In this course we take the overarching view that the mathematical study called topology grew out of an attempt to make precise the notion of continuous function in mathematics. This is one of the most difficult concepts to get across to beginning calculus students, not least because it took centuries for mathematicians themselves to get it right. The intuitive idea is natural enough, and has been around for at least four hundred years. The mathematically precise formulation dates back only to the ninteenth century, however. This is the one involving those pesky epsilons and deltas, the one that leaves most newcomers completely baffled. Why, many ask, do we even bother with this confusing definition, when there is the original intuitive one that makes perfectly good sense? In this introductory section I hope to give a believable answer to this quite natural question. -
An Introduction to Some Aspects of Functional Analysis
An introduction to some aspects of functional analysis Stephen Semmes Rice University Abstract These informal notes deal with some very basic objects in functional analysis, including norms and seminorms on vector spaces, bounded linear operators, and dual spaces of bounded linear functionals in particular. Contents 1 Norms on vector spaces 3 2 Convexity 4 3 Inner product spaces 5 4 A few simple estimates 7 5 Summable functions 8 6 p-Summable functions 9 7 p =2 10 8 Bounded continuous functions 11 9 Integral norms 12 10 Completeness 13 11 Bounded linear mappings 14 12 Continuous extensions 15 13 Bounded linear mappings, 2 15 14 Bounded linear functionals 16 1 15 ℓ1(E)∗ 18 ∗ 16 c0(E) 18 17 H¨older’s inequality 20 18 ℓp(E)∗ 20 19 Separability 22 20 An extension lemma 22 21 The Hahn–Banach theorem 23 22 Complex vector spaces 24 23 The weak∗ topology 24 24 Seminorms 25 25 The weak∗ topology, 2 26 26 The Banach–Alaoglu theorem 27 27 The weak topology 28 28 Seminorms, 2 28 29 Convergent sequences 30 30 Uniform boundedness 31 31 Examples 32 32 An embedding 33 33 Induced mappings 33 34 Continuity of norms 34 35 Infinite series 35 36 Some examples 36 37 Quotient spaces 37 38 Quotients and duality 38 39 Dual mappings 39 2 40 Second duals 39 41 Continuous functions 41 42 Bounded sets 42 43 Hahn–Banach, revisited 43 References 44 1 Norms on vector spaces Let V be a vector space over the real numbers R or the complex numbers C. -
O PAIRWISE LINDELOF SPACES
Re.v,u,ta. Coiomb.£ana de. Ma.te.mmc.M VoL XVII (1983), yJlfgJ.J. 31 - 58 o PAIRWISE LINDELOF SPACES by Ali A. FORA and Hasan L HDEIB A B ST RA CT. In this paper we define p:rirwiseLindelof spaces and study their properties and their relations with other topological spaces. We also study certain conditions by which a bitopological space will reduce to a single topology. Several examples are discussed and many well known theorems are generalized concerning Lin- delof spaces. RESUMEN. En este articulo se definen espacios p-Lin- delof y se estudian sus propiedades y relaciones con otros tipos de espacios topologicos. Tambien se estudian ciertas condiciones bajo las cuales un espacio bitopologi- co (con dos topologias) se reduce a uno con una sola topo- logla. Se discuten varios ejemplos y se generalizan va- rios teoremas sobre espacios d~ Lindelof. 1. I nt roduce ion. Kelly [6] introduced the notion of a bito- pological space, i.e. a triple (X,T1,T2) where X is a set and , T1 T2 are two topologies on X, he also defined pairwise Haus- 37 dorff, pairwise regular, pairwise normal spaces, and obtained generalizations of several standard results such as Urysohn's Lemma and the Tietze extension theorem. Several authors have since considered the problem of defining compactness for such spaces: see Kim [7], Fletcher, Hoyle and Patty [4], and Bir- san [1]. Cooke and Reilly [2] have discussed the relations be- tween these definitions. In this paper we give a definition of pairwise Lindelof bitopological spaces and derive some related results.