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    On harmonic maps from stochastically complete manifolds

    , Article Archiv der Mathematik ; Volume 92, Issue 6 , 2009 , Pages 637-644 ; 0003889X (ISSN) Ranjbar Motlagh, A. R ; Sharif University of Technology
    2009
    Abstract
    The main purpose of this article is to generalize a theorem about the size of minimal submanifolds in Euclidean spaces. In fact, we state and prove a non-existence theorem about harmonic maps from a stochastically complete manifold into a cone type domain. The proof is based on a generalized version of the maximum principle applied to the Lapalace-Beltrami operator on Riemannian manifolds. © 2009 Birkhäuser Verlag Basel/Switzerland  

    A note on isometries of Lipschitz spaces

    , Article Journal of Mathematical Analysis and Applications ; Vol. 411, Issue. 2 , 2014 , Pages 555-558 ; ISSN: 0022247X Ranjbar Motlagh, A ; Sharif University of Technology
    2014
    Abstract
    The main purpose of this article is to generalize a recent result about isometries of Lipschitz spaces. Botelho, Fleming and Jamison [2] described surjective linear isometries between vector-valued Lipschitz spaces under certain conditions. In this article, we extend the main result of [2] by removing the quasi-sub-reflexivity condition from Banach spaces  

    An integral type characterization of constant functions on metric-measure spaces

    , Article Journal of Mathematical Analysis and Applications ; Volume 385, Issue 1 , January , 2012 , Pages 194-201 ; 0022247X (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    2012
    Abstract
    The main purpose of this article is to generalize a characterization of constant functions to the context of metric-measure spaces. In fact, we approximate a measurable function, in terms of a certain integrability condition, by Lipschitz functions. Then, similar to Brezis (2002) [2], we establish a necessary and sufficient condition in order that any measurable function which satisfies an integrability condition to be constant a.e. Also, we provide a different proof for the main result of Pietruska-Pałuba (2004) [7] in the setting of Dirichlet forms  

    Generalized rademacher-stepanov type theorem and applications

    , Article Zeitschrift fur Analysis und ihre Anwendung ; Volume 28, Issue 3 , 2009 , Pages 249-275 ; 02322064 (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    2009
    Abstract
    The main purpose of this article is to generalize a theorem of Stepanov which provides a necessary and sufficient condition for almost everywhere differentiability of functions over Euclidean spaces. We state and prove an Lp-type generalization of the Stepanov theorem and then we extend it to the context of Orlicz spaces. Then, this generalized Rademacher-Stepanov type theorem is applied to the Sobolev and bounded variation maps with values into a metric space. It is shown that several generalized differentiability type theorems are valid for the Sobolev maps from a Lipschitz manifold into a metric space. As a byproduct, it is shown that the Sobolev spaces of Korevaar-Schoen and Reshetnyak... 

    A non-existence theorem for isometric immersions

    , Article Journal of Geometry and Physics ; Volume 59, Issue 3 , 2009 , Pages 263-266 ; 03930440 (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    2009
    Abstract
    Let f : M {long rightwards arrow} over(M, -) be an isometric immersion between Riemannian manifolds. For certain conditions on M and over(M, -) in terms of curvatures and external diameter, we extend the non-embedding theorem of Chern and Kuiper to the isometric immersions of non-compact manifolds. Also, our results generalize and improve the main results of Jorge and Koutroufiotis [L. Jorge, D. Koutroufiotis, An estimate for the curvature of bounded submanifolds, Amer. J. Math. 103 (4) (1981) 711-725] and Veeravalli [A. R. Veeravalli, A sharp lower bound for the Ricci curvature of bounded hypersurfaces in space forms, Bull. Austral. Math. Soc. 62 (1) (2000) 165-170]. © 2008 Elsevier B.V.... 

    An integral type characterization of lipschitz functions over metric-measure spaces

    , Article Journal of Mathematical Analysis and Applications ; Volume 479, Issue 2 , 2019 , Pages 1708-1714 ; 0022247X (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    Academic Press Inc  2019
    Abstract
    The main purpose of this article is to generalize a characterization of Lipschitz functions in the context of metric-measure spaces. The results are established in the class of metric-measure spaces which satisfy a strong version of the doubling (Bishop-Gromov regularity) condition. Indeed, we establish a necessary and sufficient condition in order that any measurable function which satisfies an integrability condition to be essentially Lipschitzian. © 2019 Elsevier Inc  

    Isometries of Lipschitz type function spaces

    , Article Mathematische Nachrichten ; Volume 291, Issue 11-12 , 2018 , Pages 1899-1907 ; 0025584X (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    Wiley-VCH Verlag  2018
    Abstract
    In this article, we describe isometries over the Lipschitz spaces under certain conditions. Indeed, we provide a unified proof for the main results of and in a more general setting. Finally, we extend our results for some other functions spaces like the space of vector-valued little Lipschitz maps and pointwise Lipschitz maps. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim  

    A remark on the bourgain-brezis-mironescu characterization of constant functions

    , Article Houston Journal of Mathematics ; Volume 46, Issue 1 , 2020 , Pages 113-115 Ranjbar Motlagh, A ; Sharif University of Technology
    University of Houston  2020
    Abstract
    The purpose of this paper is to describe a simple proof for a result originally presented by H. Brezis in [B], with roots in J. Bourgain, H. Brezis and P. Mironescu [BBM]. © 2020 University of Houston  

    A remark on isometries of absolutely continuous spaces

    , Article Journal of Function Spaces ; Volume 2020 , 2020 Ranjbar Motlagh, A ; Sharif University of Technology
    Hindawi Limited  2020
    Abstract
    The purpose of this article is to study the isometries between vector-valued absolutely continuous function spaces, over compact subsets of the real line. Indeed, under certain conditions, it is shown that such isometries can be represented as a weighted composition operator. © 2020 Alireza Ranjbar-Motlagh  

    Generalizations of the Liouville theorem

    , Article Differential Geometry and its Application ; Volume 26, Issue 3 , 2008 , Pages 339-345 ; 09262245 (ISSN) Ranjbar-Motlagh, A ; Sharif University of Technology
    2008
    Abstract
    The purpose of this paper is to generalize the Liouville theorem for functions which are defined on the complete Riemannian manifolds. Then, we apply it to the isometric immersions between complete Riemannian manifolds in order to obtain an estimate for the size of the image of immersions in terms of the supremum of the length of their mean curvature vector in a quite general setting. The proofs are based on the Calabi's generalization of maximum principle for functions which are not necessarily differentiable. © 2007 Elsevier B.V. All rights reserved  

    Isometries between spaces of vector-valued differentiable functions

    , Article Journal of Function Spaces ; Volume 2021 , 2021 ; 23148896 (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    Hindawi Limited  2021
    Abstract
    This article characterizes the isometries between spaces of all differentiable functions from a compact interval of the real line into a strictly convex Banach space. © 2021 Alireza Ranjbar-Motlagh  

    A note on the Poincaré inequality

    , Article Studia Mathematica ; Volume 154, Issue 1 , 2003 , Pages 1-11 ; 00393223 (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    Instytut Matematyczny  2003
    Abstract
    The Poincaré inequality is extended to uniformly doubling metric-measure spaces which satisfy a version of the triangle comparison property. The proof is based on a generalization of the change of variables formula  

    Besov type function spaces defined on metric-measure spaces

    , Article Journal of Mathematical Analysis and Applications ; Volume 505, Issue 2 , 2022 ; 0022247X (ISSN) Ranjbar Motlagh, A ; Sharif University of Technology
    Academic Press Inc  2022
    Abstract
    The purpose of this article is to study the Besov type function spaces for maps which are defined on abstract metric-measure spaces. We extend some of the embedding theorems of the classical Besov spaces to the setting of abstract spaces. © 2021 Elsevier Inc  

    Poincaré inequality for abstract spaces

    , Article Bulletin of the Australian Mathematical Society ; Volume 71, Issue 2 , 2005 , Pages 193-204 ; 00049727 (ISSN) Ranjbar-Motlagh, A ; Sharif University of Technology
    Australian Mathematical Publishing Association  2005
    Abstract
    The Poincaré inequality is generalised to metric-measure spaces which support a strong version of the doubling condition. This generalises the Poincaré inequality for manifolds whose Ricci curvature is bounded from below and metric-measure spaces which satisfy the measure contraction property. Copyright Clearance Centre, Inc  

    Global Regularity of Wave Maps

    , M.Sc. Thesis Sharif University of Technology Kasebian, Kaveh (Author) ; Ranjbar Motlagh, Alireza (Supervisor)

    An Extension of Hedberg’s Convolution Inequality and Applications

    , M.Sc. Thesis Sharif University of Technology Shahi, Amir (Author) ; Ranjbar Motlagh, Alireza (Supervisor)
    Abstract
    HAedbbergshtasrpraovecdtthefolowinginequalityforany1pnof;nandpIsuchft(xa)tCkfkpnp(Mf(x)1np .8Tfh2erLepe(xRisnt)saCindependent fHwuhhenedecrSbteioeobrnIgo'losefvinffie.nqieusqautlhiatleyityhReefloipsrsztihpneodtReenaeltiisinazglpwooftitefhntpaiarnlod,bil.Meem.fsrdeelnatoitnegtuhseinHgatrhdeyf-uLnitcttlieowno.ofodrmexaaxmimpalel SwohbeorelevCiniseqinudaeliptyencdaenntbeofexft,racactnkeIdbefrdofmekdnuHnspeepddbferroCgm'ksfHinepedqbuearlgit'ys.iHneeqrueawlietyw.iAllgseontehraeliczleasHsiecda-l berg'sinequalitytoOrliczspaces.
     

    Hardy Inequalities

    , M.Sc. Thesis Sharif University of Technology Tavakkoli, Mohsen (Author) ; Ranjbar Motlagh, Alireza (Supervisor)
    Abstract
    In this thesis, it has been introduced Hardy inequality and it’s extends. The fractional Hardy inequality for Ω ⊆ Rn and f ∈ C ∞ (Ω) is:1f (x) − f ( y)2∫α +n2dx dy ≥ kn,α ∫f (x)dx( )αΩ×Ωx − yΩ M α x In this thesis we are going to introduce the fractional and derivative forms of Hardy inequality then the Hardy inequality will be proved to fractional form on Euclidean and Hyperbolic domains, and finally we will get right into Hardy inequality with remainder.
     

    Schaefer–Krasnoselskii Fixed Point Theorems Using a Usual Measure of Weak Noncompactness

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Sajjad (Author) ; Ranjbar Motlagh, Alireza (Supervisor)
    Abstract
    In this thesis, we present some extension of Burton and Kirk fixed point theorem for the sum of two nonlinear operators, which one of them is compact and the other one is strict contraction; and we investigate the existence of fixed point where these two operators don’t need to be weakly continuous. Next, we will check the necessity of some conditions, like being strict contraction or compactness, in some specific Banach spaces, such as reflective spaces or Banach spaces equipped with uniformly convex norm.Finally, we analysis the existence of the solution for integral equations in L1 space by using the expressed theorems  

    Boundedness of Calderón-Zygmund Singular Inegral Operators

    , M.Sc. Thesis Sharif University of Technology Pourmohammad, Hassan (Author) ; Ranjbar-Motlagh, Alireza (Supervisor)
    Abstract
    The so called T(b) theorem for boundedness of generalized CalderonZygmund singular integrals is investigated. This theorem provides a criterion, in which boundedness of the operator is equivalent to a special condition for the image of some function under action of that operator.Then we discuss some applications of the theorem in analysis and partial differential equations  

    Extreme Points and Isometries on Vector-Valued Lipschitz Spaces

    , M.Sc. Thesis Sharif University of Technology Behrouzi, Shadi (Author) ; Ranjbar-Motlagh, Alireza (Supervisor)
    Abstract
    For a Banach space E and a compact metric space (X, d), a function F : X → E is a Lipschitz function if there exists k > 0 such that ∥F (x) − F (y)∥ ≤ kd(x, y) for all x, y ∈ X.The smallest such k is called the Lipschitz constant L(F ) for F . The space Lip(X, E) of all Lipschitz functions from X to E is a Banach space under the norm defined by ∥F ∥ = max{L(F ), ∥F ∥∞}, where ∥F ∥∞ = sup{∥F (x)∥ : x ∈ X}.Recent results characterizing isometries on these vector-valued Lipschitz spaces require the Banach space E to be strictly convex. We inves- tigate the nature of the extreme points of the dual ball for Lip(X, E) and use the information to describe the surjective isometries on Lip(X, E) under...