On the Equivalence Functional Relation Estimated for Vector-Valued Singular Integrals with Semigroups of Operators
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Republic of the Sudan Ministry of High Education and Scientific Research University of Nile Valley Faculty of Postgraduate Studies On The Equivalence Functional Relation Estimated For Vector-Valued Singular Integrals with Semigroups of Operators. A Thesis Submitted in Partial Fulfillment for the Degree of M.sc in Mathematics Prepared by: Mohammed Salih Mukhtar Dahab Ahmed Supervised by: Dr. Adam Abedalla Abbakar Hassan December, 2009 اﻵية ق ال اهلل تعالي ِ ِ }يَْومَ نَطْوِي السََّماء َكطَ ِّي السِّجلِّ لْل ُكتُ ِب كََما بَدَأْنَ ا أَوَّلَ ِ ِِ خَْل ٍق نُّعيدُهُ َو ْعداً عَل َْينَ ا إِن َّا ُكن َّا ف َاعلي َن {اﻷنبياء401 وق ال اهلل تعالي أيضا ِ ِ }َوَما قَدَُروا اللَّوَ َح َّق قَ ْدرِه َواْﻷَْر ُض َجميعا ً قَْب َضتُوُ يَْومَ ِ ِ ِ ِ ِِ اْلقيَ اَمة َوالسَّماَوا ُت َمطْوِي َّا ٌت بيَمينو ُسْبَحانَوُ َوتََعالَى عَمَّا يُ ْشرِ ُكو َن {الزمر76 وق ال اهلل تعالي أيضا ِ ٍ ِ }َوالسََّماء بَنَْينَ ا َىا بأَْيد َوإِن َّا لَُموسُعو َن * َواْﻷَْر َض فََر ْشنَ ا َىا فَنِعم اْلما ِىدون {الذاريات16، 14 ْ َ َ ُ َ صدق اهلل العظيم Dedication TO My parents who survived for me to be i My great thanks after my God to my supervisor Dr. Adam Abedd- Alla Abbakar who suggested this title , for his wise advice and guidance. Thanks are Also due to the library staff of the Facluty of Mathematical Sciences U.of.K and especially for Mr. Mohammed Yasein the secretary. Also are extended to the teaching staff and administrators of the M.sc program at the Nile Valley University Omdurman branch. ii Abstract In this thesis we have present a mathematical techniques in estimation of vector – valued singular integral by using equivalence functional relations with semigroups of operators. This thesis contains four chapters. The first chapter is the function and the functional relations. The second chapter with the title vector – valued singular integrals. Chapter three under the title of semigroups and semigroups of operators. The last , chapter four, in which the estimation of the singular integragrls have been done by developing a generalized Littlewood-paley theory for semigroups acting on Lp -spaces of functions with values in uniformly convex or smooth Banach spaces, this general theory becomes more satisfactory (and easier to be handled) in virtue of the theory of vector-valued Calder´on-Zygmund singular integral operators. iii الخﻻصة قددت في ددًيهدد ي لبحددبيب ددتي لات ٌدديفي ل ٌيمددٌدي ل ددا ت دي ددًياتددتٌ ي لامددي في ل ف تةيأوي لشي ةيي في لتٌ ددي تاايهٌددي لادًيا دا تعي ل قديفي لت لٌددي د ي دثر في شبهي لز .يٌحاوييهد ي لبحدبيليدًيأ ب ددي دو ي,ي لف د ي وو يب دو اي لت لدديوي ل قيفي لت لٌدي,يو لف ي لري ًيٌ ا تي لفمديا في ل ااهدديو لامدي في ل فد تةي أوي لشددي ةيي يآفي لتٌ دددي تاايهٌدددي.ي لف دد ي لريلددبيلدداي ددثر فيشددبهي لز دد ي,يأ دديي لبيبي ل ب يو و ٌ ياعي ٌهياتتٌ يايكي لامدي فيلدايي ٌدطيايدوٌ ي ظ ٌدديلٌايدووتي –يبٌيى(Littlewood-Paley theory) يلشبهي لز ي لاًيادثر ي دًيتو ي مديا في لبٌ ددٌج)Lebeseque space)ي في لتٌ دددي ددًي بدديفيبي ددي (Banach space)ي له ت ٌدي ل اظ دي ل حتبد(convex)يأويي لافيميٌدي ل يل د)smooth(يلا دبحيهد هي ل ظ ٌدي في فسي ٌزةي ثر فيميلٌت واي–يز ٌت و تييليامي في ل ف تةيأوي لشدي ةيي في لتٌ دددي تاايهٌدددي Calderon-Zagmound vector-valued singular) (integrals ي ي vi v List of contents Dedication…………………………………………………………i Acknoweledgement…………………………………………….…ii Abstract…………………………………………………………...iii Abstract (Arabic)………………………………………………....iv List of contents……..……………………………….…………….v List of symbols and abbreviations……………………………….vii Introduction……………………………………………….………x Chapter one 1-Function and functional relations.….…………………….……..1 11 The function…………………………………………………………..1 12 The functional relations…………………………………………6 13 The equivalence functional relations……………………..18 Chapter two 2-Vector –valued singular integrals……………………………..27 21 Vector space……………………………………………....28 22 Topological vector space…………………………………29 23 Kernel mathematic………………………………………..32 24 Convolution………………………………………………………..40 25 Integral transform……………………………………………….42 26 Singular integrals………………………………………………..43 27 Hardy – Littlewood maximal function…………………..47 28 Littlewood-Paley theory……………………………………….50 29 Fefferman - Stein function and vector-valued operators...53 v Chapter three 3-Semigroups and semigroups of operators……………………55 31 The semigroups…………………………………………...56 32 Semigroups action………………………………….…….60 33 Transformation semigroup………………………………..63 34 Inverse semigroup………………………………………...64 35 Semigroups of operators………………………………….67 36 Hille–Yosida theorem……………………………………69 37 C0-semigroup……………………………………………72 38 Special integral operators…………………………………77 Chapter four 4-Estimation of vector-valued singular integrals with semigroups of operators………………………………………………...……87 41 Developing a generalized Littlewood-Paley theory for semigroups acting on Lp -spaces…………………………………89 42 One-sided vector-valued Littlewood-Paley-Stein inequalities for semigroups………………………………………94 43 Duality…………………………………………………..110 44 Poisson semigroup on Rn ……………………………..113 45 Continuation of Poisson semigroup on Rn ……………..121 46 Ornstein-Uhlenbeck semigroup…………………………126 47 Almost sure finiteness…………………………………..130 References…………………………….………………………..137 vi List of symbols and abbreviations f Function CC, 0 Set of continuous functions R \0 Domain of real numbers except zero X Equivalence class : Binary relation ,,,,,,:; Equivalence relations ConX Complete lattice ker Mathematical kernel Rn N-dimensional Euclidean space (CZO) Calderón-Zygmund Operator (UMD) unconditional martingale differences The norm Lp Lebesgue spaces W kp, Sobolev spaces vii P Poisson kernel H p Hardy space M Maximal function gf Littlewood-Paley g- function f # The sharp maximal function Q Cubes H Hilbert space B Banach space Ttt0 Diffusion semigroup W Weierstrass Operators Gradient operator The Laplace operator n Gaussian measure L Ornstein–Uhlenbeck operator BMO Bounded mean oscillator G The classical Littlewood-Paley g -function viii Pt t0 The subordinated Poisson semigroup A The infinitesimal generator of semigroup q g -function” associated to subordinated Poisson semigroup T Torus Gq n -dimensional generalized g-function n Ott0 The Ornstein-Uhlenbeck semigroup on R O t t0 Poisson semigroup subordinated to the Ornstein-Uhlenbeck semigroup on gq Littlewood-Paley g -function associated to En Monotone sequence of conditional Expectations n Pt Poisson kernels both on and on R dμ Lebesgue measure Pr Poisson kernels on ix Introduction In this thesis we have to present a mathematical technique in estimation of vector – valued singular integral by using equivalence functional relations with semigroups of operators. This thesis contains four chapters. the first chapter is the function and the functional relations, in which we have introduced basic results of the function its (definition, representation, notation, properties and continuity), the functional relations (injection, bijection, surjection, isometry and homomorphism) and the equivalence functional relations with the known notations ,,,,, that used as tools to compare between mathematical terms or structures and help us to estimate. In the second chapter with the title vector – valued singular integrals we start with the vector space and topological vector spaces and their properties examples are Banach spaces, Hilbert spaces and Sobolev spaces. Those spaces are underlying valued spaces for the functions define and bounded on them. After this we view the technique to achieve the singular integral by giving definition , meaning ,and properties of the kernels like (Calderon – Zagmund kernels , Poisson kernels), then we introduce the convolution , where the singular integral is an integral transform given by convolution of the function against the kernels , also the integrable function ( Lebesque measurable functions and Bochner integrals) , integral transform , Hilbert transform in harmonic analysis in the L2 space, from this view we have studied the Calderon – Zagmund singular operator with kernels in Rn . The rest of this chapter studies the development of the function to maximal function, Hrdy-Littlewood maximal functions, Littlewood – Paley theory and Fefferman Stein extension to the latter theory. That sharp maximal function f # is defined as regarding singular integrals. x In chapter three under the title of semigroups of operators, we exhibits the semigroups with it’s definition, types, structure, action, and it’s properties. Then we introduce the semigroup operators its definition and generation, under the fundamental Hille–Yosida theorem we study the C0-semigroup and its infinitesimal operator, also known as a (strongly continuous) one-parameter semigroup, the transformation and the analytical semigroup are special type of the C0-semigroup Then we define the symmetric diffusion semigroup ,it is a collection of linear operators Ttt0 defined on Ldp , over a measure space ,d which is used in the solution of the partial differential equation and share the same application with the singular integral. At the end of this chapter we introduce some integral operators with semigroups properties, The Weierstrass operators, Poisson operator, and the Ornstein– Uhlenbeck operator used in the development of Littlewood-Paley generalized function for the semigroups in spaces. The last , chapter four, in which the estimation of the singular integragrls have been done by developing a generalized Littlewood-paley theory for semigroups acting on Lp -spaces of functions. It is well known that martingale inequalities involving square function are closely related to the corresponding inequalities