Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201A lower estimate of harmonic functions17479ENGuoshuang PanBeijing National Day SchoolLei QiaoDepartment of Mathematics and Information Science, Henan University of Economics and Law, Zhengzhou, People's Republic of ChinaGuantie DengSchool of Mathematical
Science, Beijing Normal University, Beijing, People's Republic of China.Journal Article20120910We shall give a lower estimate of harmonic functions of order greater than one in a half space, which <br />generalize the result obtained by B. Ya. Levin in a half plane.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Investigation on the Hermitian matrix expression subject to some consistent equations928480ENXiang ZhangDepartment of Mathematics, Zunyi Normal College Shanghai Road, Zunyi
563000, P.R. ChinaJournal Article20120520In this paper, we study the extremal <br />ranks and inertias of the Hermitian matrix expression $$ <br />f(X,Y)=C_{4}-B_{4}Y-(B_{4}Y)^{*}-A_{4}XA_{4}^{*},$$ where $C_{4}$ is <br />Hermitian, $*$ denotes the conjugate transpose, $X$ and $Y$ satisfy <br />the following consistent system of matrix equations $A_{3}Y=C_{3}, <br />A_{1}X=C_{1},XB_{1}=D_{1},A_{2}XA_{2}^{*}=C_{2},X=X^{*}.$ As <br />consequences, we get the necessary and sufficient conditions for the <br />above expression $f(X,Y)$ to be (semi) positive, (semi) negative. <br />The relations between the Hermitian part of the solution to the <br />matrix equation $A_{3}Y=C_{3}$ and the Hermitian solution to the <br />system of matrix equations <br />$A_{1}X=C_{1},XB_{1}=D_{1},A_{2}XA_{2}^{*}=C_{2}$ are also <br />characterized. Moreover, we give the necessary and sufficient <br />conditions for the solvability to the <br />following system of matrix equations <br />$A_{3}Y=C_{3},A_{1}X=C_{1},XB_{1}=D_{1}, <br />A_{2}XA_{2}^{*}=C_{2},X=X^{*}, <br />B_{4}Y+(B_{4}Y)^{*}+A_{4}XA_{4}^{*}=C_{4} $ and provide an <br />expression of the general solution to this system <br />when it is solvable.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Coupled fixed point results for weakly related mappings in partially ordered metric spaces2940481ENNaval Singhgovt. benazir college, bhopalReena JainTechnocrats Institute of technologyJournal Article20120215In the present paper, we show the existence of a coupled fixed point for a non-decreasing mapping in partially ordered complete metric space using a partial order induced by an appropriate function $phi$. We also define the concept of weakly related mappings on an ordered space. Moreover common coupled fixed points for two and three weakly related mappings are also proved in the same space.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201A matrix LSQR algorithm for solving constrained linear operator equations4153482ENMasoud HajarianDepartment of Mathematics
Faculty of Mathematical Sciences
Shahid Beheshti University, G.C.,
Evin, Tehran 19839
IranJournal Article20120709In this work, an iterative method based on a matrix form of LSQR algorithm is constructed for solving the linear operator equation $mathcal{A}(X)=B$ <br />and the minimum Frobenius norm residual problem $||mathcal{A}(X)-B||_F$ <br />where $Xin mathcal{S}:={Xin textsf{R}^{ntimes n}~|~X=mathcal{G}(X)}$, $mathcal{F}$ is the linear operator from $textsf{R}^{ntimes n}$ onto $textsf{R}^{rtimes s}$, <br />$mathcal{G}$ is a linear self-conjugate involution operator and <br />$Bin textsf{R}^{rtimes s}$. <br />Numerical examples are given to verify the efficiency of the constructed method.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Maximal prehomogeneous subspaces on classical groups5581483ENXiaoxiang YuXuzhou Normal University,
P.R.ChinaDengyin WangChina University of Mining and technologyJournal Article20111209Suppose $G$ is a split connected reductive orthogonal or symplectic group over an infinite field <br />$F,$ $P=MN$ is a maximal parabolic subgroup of $G,$ $frak{n}$ is <br />the Lie algebra of the unipotent radical $N.$ Under the adjoint <br />action of its stabilizer in $M,$ every maximal prehomogeneous <br />subspaces of $frak{n}$ is determined.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Sequential second derivative general linear methods for stiff systems83100484ENAli KaramEzzeddineUniversity of TabrizGholamreza HojjatiUniversity of TabrizAli AbdiUniversity of TabrizJournal Article20120903Second derivative general linear methods (SGLMs) as an extension <br />of general linear methods (GLMs) have been introduced to improve <br />the stability and accuracy properties of GLMs. The coefficients of <br />SGLMs are given by six matrices, instead of four matrices for <br />GLMs, which are obtained by solving nonlinear systems of order and <br />usually Runge--Kutta stability conditions. In this paper, we <br />introduce a technique for construction of an special case of SGLMs <br />which decreases the complexity of finding coefficients matrices.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201On the numerical solution of generalized Sylvester matrix equations101113485ENAmer KaabiiranJournal Article20111116The global FOM and GMRES algorithms are among the effective <br />methods to solve Sylvester matrix equations. In this paper, we <br />study these algorithms in the case that the coefficient matrices <br />are real symmetric (real symmetric positive definite) and extract <br />two CG-type algorithms for solving generalized Sylvester matrix <br />equations. The proposed methods are iterative projection methods <br />onto matrix Krylov subspaces. Numerical examples are presented.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201An extension theorem for finite positive measures on surfaces of finite dimensional unit balls in Hilbert spaces115124486ENAhmad Reza SoltaniKuwait University and Shiraz UniversitySafieh MahmoodiIsfahan University of TechnologyJournal Article20120224A consistency criteria is given for a certain class of finite positive <br />measures on the surfaces of the finite dimensional unit balls in a real <br />separable Hilbert space. It is proved, through a Kolmogorov type existence <br />theorem, that the class induces a unique positive measure on the surface of <br />the unit ball in the Hilbert space. As an application, this will naturally <br />accomplish the work of Kanter (1973) on the existence and uniqueness of the <br />spectral measures of finite dimensional stable random vectors to the <br />infinite dimensional ones. The approach presented here is direct and <br />different from the functional analysis approach in Kuelbs (1973), Linde <br />(1983) and the indirect approach of Tortrat (1976) and Dettweiler (1976).Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Embedding measure spaces125155487ENM.R. KousheshIsfahan University of TechnologyJournal Article20121030For a given measure space $(X,{mathscr B},mu)$ we construct all measure spaces $(Y,{mathscr C},lambda)$ in which $(X,{mathscr B},mu)$ is embeddable. The construction is modeled on the ultrafilter construction of the Stone--v{C}ech compactification of a completely regular topological space. Under certain conditions the construction simplifies. Examples are given when this simplification occurs.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201A class of Artinian local rings of homogeneous type157181488ENLeila SharifanHakim Sabzevari University, Sabzevar, IranJournal Article20120715Let $I$ be an ideal in a regular local ring $(R,n)$, we will find <br />bounds on the first and the last Betti numbers of <br />$(A,m)=(R/I,n/I)$. if $A$ is an Artinian ring of the embedding <br />codimension $h$, $I$ has the initial degree $t$ and $mu(m^t)=1$, <br />we call $A$ a {it $t-$extended stretched local ring}. This class of <br />local rings is a natural generalization of the class of stretched local rings studied by Sally, Elias and Valla. For a $t-$extended stretched local ring, <br />we show that ${h+t-2choose t-1}-h+1leq tau(A)leq {h+t-2choose <br />t-1}$ and $ {h+t-1choose t}-1 leq mu(I) leq {h+t-1choose t}$. <br />Moreover $tau(A)$ reaches the upper bound if and only if $mu(I)$ <br />is the maximum value. Using these results, we show when <br />$beta_i(A)=beta_i(gr_m(A))$ for each $igeq 0$. Beside, we will <br />investigate the rigid behavior of the Betti numbers of $A$ in the <br />case that $I$ has initial degree $t$ and $mu(m^t)=2$. This class <br />is a natural generalization of {it almost stretched local rings} <br />again studied by Elias and Valla. Our research extends several <br />results of two papers by Rossi, Elias and Valla.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Stochastic bounds for a single server queue with general retrial times183198489ENMohamed BoualemUniversity of BejaiaNatalia DjellabUniversity of AnnabaDjamil AïssaniUniversity of béjaiaJournal Article20120629We propose to use a mathematical method based on stochastic comparisons of Markov chains in order to derive performance indice bounds. The main goal of this paper is to investigate various monotonicity properties of a single server retrial queue with first-come-first-served (FCFS) orbit and general retrial times using the stochastic ordering techniques.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Existence and uniqueness of common coupled fixed point results via auxiliary functions199215490ENSumit ChandokKhalsa College of Engineering & Technology (Punjab Technical University)Erdal KarapinarATILIM UNIVERSITYMohammad Saeed KhanSultan Qaboos UniversityJournal Article20120401The purpose of this paper is to establish some coupled coincidence point theorems for mappings having a mixed $g$-monotone property in partially ordered metric spaces. Also, we present a result on the existence and uniqueness of coupled common fixed points. The results presented in the paper generalize and extend several well-known results in the literature.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Relative volume comparison theorems in Finsler geometry and their applications217234491ENBing Ye WuDepartment of Mathematics
Minjiang UniversityJournal Article20120301We establish some relative volume comparison theorems for extremal volume forms of Finsler manifolds under suitable curvature bounds. As their applications, we obtain some results on curvature and topology of Finsler manifolds. Our results remove the usual assumption on S-curvature that is needed in the literature.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201An eigenvalue study on the sufficient descent property of a modified Polak-Ribière-Polyak conjugate gradient method235242492ENSaman Babaie-KafakiSemnan UniversityJournal Article20120824Based on an eigenvalue analysis, a new proof for the sufficient descent property of the modified Polak-Ribière-Polyak conjugate gradient method proposed by Yu et al. is presented.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Various kinds of regular injectivity for $S$-posets243261493ENLeila ShahbazUniversity of MaraghehMojgan MahmoudiShahid Beheshti UniversityJournal Article20120418In this paper some properties of weak regular injectivity for $S$-posets, <br />where $S$ is a pomonoid, are studied. The behaviour <br />of different kinds of weak regular injectivity with products, coproducts and direct sums is considered. Also, some <br />characterizations of pomonoids over which all $S$-posets are of <br />some kind of weakly regular injective are obtained. Further, we <br />give some Baer conditions which state the relation among some <br />kinds of weak regular injectivity.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201Implicit iteration approximation for a finite family of asymptotically quasi-pseudocontractive type mappings263279494ENShuyi ZhangDepartment of Mathematics, BoHai UniversityJournal Article20111206In this paper, strong convergence theorems of Ishikawa type implicit iteration <br />process with errors for a finite family of asymptotically <br />nonexpansive in the intermediate sense and asymptotically <br />quasi-pseudocontractive type mappings in normed linear spaces are <br />established by using a new analytical method, which essentially <br />improve and extend some recent results obtained by Yang <br />[Convergence theorems of implicit iteration process for <br />asymptotically pseudocontractive mappings, Bulletin of the Iranian <br />Mathematical Society, Available Online from 12 April 2011] and <br />others.Iranian Mathematical Society (IMS)Bulletin of the Iranian Mathematical Society1017-060X40120140201On the norm of the derived subgroups of all subgroups of a finite group281291495ENZhencai ShenLMAM and School of Mathematical Sciences, Peking
University,
Beijing, 100871, China.Shirong LiGuangxi UniversityWujie ShiChongqing University of Arts and SciencesJournal Article20120630In this paper, we give a complete proof of Theorem 4.1(ii) and a new elementary proof of Theorem 4.1(i) in [Li and Shen, On the intersection of the normalizers of the derived subgroups of all <br />subgroups of a finite group, J. Algebra, 323 (2010) 1349--1357]. <br />In addition, we also give a generalization of Baer's Theorem.