I • • 11 ISNM International Series of Numerical Mathematics Volume 157 Managing Editors: K.-H. Hoffmann, Bonn D. Mittelmann, Tempe Associate Editors: R. E. Bank, La Jolla H. Kawarada, Chiba R. J. LeVeque, Seattle C. Verdi, Milano Honorary Editor: J. Todd, Pasadena Inequalities and Applications Conference on Inequalities and Applications, Noszvaj (Hungary), September 2007 Catherine Bandle Attila Gilányi László Losonczi Zsolt Páles Michael Plum Editors Birkhäuser Basel · Boston · Berlin Editors: Catherine Bandle Attila Gilányi Institut Mathematik Zsolt Páles Universität Basel Department of Analysis Rheinsprung 21 Institute Mathematics & Informatics 4051 Basel University of Debrecen Switzerland Pf. 12 Email: [email protected] 4010 Debrecen Hungary László Losonczi Email: [email protected] Department Economic Analysis & [email protected] Information Technology for Business University of Debrecen Michael Plum Kassai út.26 Institut für Analysis 4028 Debrecen Universität Karlsruhe Hungary Kaiserstrasse 12 Email: [email protected] 76128 Karlsruhe Germany Email: [email protected] 2000 Mathematics Subject Classification: 15-06, 15A39,15A42, 15A45, 26D05, 26D07, 26D10, 26D15, 26D20, 26E60, 30A10, 32A22, 34A40, 35J85, 35K85, 35L85, 35R45, 39B72, 41A17, 42A05, 47A30, 47A50, 47A63, 47J20, 49J40, 51M16, 52A40, 58E35, 60E15 Library of Congress Control Number: 2008935754 Bibliographic information published by Die Deutsche Bibliothek. Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the Internet at http://dnb.ddb.de ISBN 978-3-7643-8772-3 Birkhäuser Verlag AG, Basel - Boston - Berlin This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illustrations, recitation, broadcasting, reproduction on microfilms or in other ways, and storage in data banks. For any kind of use permission of the copyright owner must be obtained. © 2009 Birkhäuser Verlag AG Basel · Boston · Berlin P.O. Box 133, CH-4010 Basel, Switzerland Part of Springer Science+Business Media Printed on acid-free paper produced from chlorine-free pulp. TCF ∞ Printed in Germany ISBN 978-3-7643-8772-3 e-ISBN 978-3-7643-8773-0 9 8 7 6 5 4 3 2 1 www.birkhauser.ch Contents Preface ................................................................... ix Abstracts of Talks ........................................................ xi Problems and Remarks ..................................................... xli List of Participants ....................................................... xlvii Part I: Inequalities Related to Ordinary and Partial Differential Equations C. Bandle A Rayleigh-Faber-KrahnInequalitiy and Some Monotonicity Properties for Eigenvalue Problems with Mixed Boundary Conditions ........... 3 H. Behnke Lower and Upper Bounds for Sloshing Frequencies ................... 13 B.M. Brown, V. Hoang, Michael Plum and I.G. Wood On Spectral Bounds for Photonic Crystal Waveguides ................ 23 C. Bu¸se Real Integrability Conditions for the Nonuniform Exponential Stability of Evolution Families on Banach Spaces .................... 31 K. Nagatou Validated Computations for Fundamental Solutions of Linear Ordinary Differential Equations ............................... 43 Part II: Integral Inequalities S. Barza and L.-E. Persson Equivalence of Modular Inequalities of Hardy Type on Non-negative Respective Non-increasing Functions ................... 53 R.C. Brown and D.B. Hinton Some One Variable Weighted Norm Inequalities and Their Applications to Sturm-Liouville and Other Differential Operators .... 61 vi Contents P. Cerone Bounding the Gini Mean Difference .................................. 77 B. Gavrea On Some Integral Inequalities ........................................ 91 M. Johansson A New Characterizationof the Hardy and Its Limit Po´lya-Knopp Inequality for Decreasing Functions .................................. 97 A. Cˇivljak, Lj. Dedi´c and M. Mati´c Euler-Gru¨ss Type Inequalities Involving Measures .................... 109 W.D. Evans, A. Gogatishvili and B. Opic The ρ-quasiconcaveFunctions and Weighted Inequalities ............. 121 Part III: Inequalities for Operators S.S. Dragomir Inequalities for the Norm and Numerical Radius of Composite Operators in Hilbert Spaces ......................................... 135 F. Kittaneh Norm Inequalities for Commutators of Normal Operators ............ 147 J. Matkowski Uniformly Continuous Superposition Operators in the Spaces of Differentiable Functions and Absolutely Continuous Functions ....... 155 T. Ogita and S. Oishi Tight Enclosures of Solutions of Linear Systems ..................... 167 Part IV: Inequalities in Approximation Theory I. Gavrea Operators of Bernstein-Stancu Type and the Monotonicity of Some Sequences Involving Convex Functions ......................... 181 A.I. Mitrea and P. Mitrea Inequalities Involving the Superdense Unbounded Divergence of Some Approximation Processes ...................................... 193 C.P. Niculescu An Overview of Absolute Continuity and Its Applications ............ 201 Contents vii Part V: Generalizations of Convexity and Inequalities for Means S. Abramovich and S.S. Dragomir Normalized Jensen Functional, Superquadracity and Related Inequalities ................................................. 217 P. Burai Comparability of Certain Homogeneous Means ....................... 229 M. Klariˇci´c Bakula, M. Mati´c and J. Peˇcari´c On Some General Inequalities Related to Jensen’s Inequality ......... 233 A.W. Marshall and I. Olkin Schur-Convexity,Gamma Functions, and Moments ................... 245 Z. Dar´oczy and Zs. P´ales A Characterizationof Nonconvexity and Its Applications in the Theory of Quasi-arithmetic Means ............................ 251 J. Mrowiec, Ja. Tabor and J´o. Tabor Approximately Midconvex Functions ................................. 261 Part VI: Inequalities, Stability, and Functional Equations W. Fechner and J. Sikorska Sandwich Theorems for Orthogonally Additive Functions ............ 269 R. Ger On Vector Pexider Differences Controlled by Scalar Ones ............ 283 Gy. Maksa and F. M´esza´ros A Characterizationof the Exponential Distribution through Functional Equations ................................................ 291 D. Popa Approximate Solutions of the Linear Equation ....................... 299 A. Varga and Cs. Vincze On a Functional Equation Containing Weighted Arithmetic Means ................................................... 305 Preface Inequalitiesarefoundinalmostallfieldsofpureandappliedmathematics.Because of their various applications in areas such as the natural and engineering sciences as well as economics, new types of interesting inequalities are discovered every year. In the theory of differential equations, in the calculus of variations and in geometry, fields which are dominated by inequalities, efforts are made to extend and improve the classical ones. Thestudyofinequalitiesreflectsthedifferentaspectsofmodernmathematics. On one hand, there is the systematic search for the basic principles, such as the deeper understanding of monotonicity and convexity. On the other hand, finding thesolutionstoaninequalityrequiresoftennewideas.Someofthemhavebecome standard tools in mathematics. In view of the wide-ranging research related to inequalities,severalrecentmathematicalperiodicalshavebeendevotedexclusively to this topic. Apossible wayto speedup the communicationbetweengroupsofspecialists of the seemingly unconnected areas is to bring them together from many parts of theglobe.DuetotheeffortsofJ´anosAcz´el,GeorgAumann,EdwinF.Beckenbach, RichardBellmanand WolfgangWalter,the firstGeneralInequalities meeting was organizedin Oberwolfach,Germany in 1976.Then six meetings wereorganizedin Oberwolfach between 1978 and 1995 and one in Noszvaj, Hungary in 2002. The Conference on Inequalities and Applications ’07 also took place at the De La Motte Castle in Noszvaj, Hungary from September 9 to 15, 2007. It was organized by the Department of Analysis of the University of Debrecen. The members of the Scientific Committee were Catherine Bandle (Basel), William Norrie Everitt (Birmingham, honorary member), La´szl´o Losonczi (De- brecen), Zsolt P´ales (Debrecen), Michael Plum (Karlsruhe) and Wolfgang Walter (Karlsruhe, honorary member). TheorganizingCommitteeconsistedofZolt´anDaro´czy(honorarychairman), Attila Gila´nyi (chairman), Miha´ly Bessenyei (scientific secretary), Zolt´an Boros, Gyula Maksa, Szabolcs Baja´k and Fruzsina M´esz´aros.There were 66 participants from 16 countries. The talks at the symposium focused on the following topics: convexity and its generalizations; mean values and functional inequalities; matrix and operator inequalities;inequalitiesforordinaryandpartialdifferentialoperators;integraland differential inequalities; variational inequalities; numerical methods. A number of x Preface sessions were, as usual, devoted to problems and remarks. The scientific program was complemented by several social events, such as a harpsichord recital of some masterpieces of Bach and Haydn, performed by A´gnes V´arallyay. This volume contains 33 research papers, about half of the works presented at the meeting. The material is arranged into six chapters ranging from Inequali- ties related to ordinary and partial differential equations to Inequalities, stability, and functional equations. The contributions given here reflect the ramification of inequalitiesintomanyareasofmathematics,andalsopresentasynthesisofresults in both theory and practice. The editors of the volume are thankful to Mrs. Phyllis H. Brown for the artistic drawings made at the conference, which are illustrations to the six chap- ters.They thank Miha´lyBessenyeifor enthusiasticallycompilingthe reportofthe meeting,AndreaPa´kozdyforthepreparationofthemanuscriptsandthepublisher, Birkh¨auser Verlag, for the careful typesetting and technical assistance. The organizationofthe meeting and the publicationof the proceedings were partially supported by the Hungarian Scientific ResearchFund Grants NK–68040 and K–62316. The Editors