Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 A lower estimate of harmonic functions 1 7 EN Guoshuang Pan Beijing National Day School gsp1979@163.com Lei Qiao Department of Mathematics and Information Science, Henan University of Economics and Law, Zhengzhou, People's Republic of China qiaocqu@163.com Guantie Deng School of Mathematical Science, Beijing Normal University, Beijing, People's Republic of China. denggt@bnu.edu.cn We 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. Lower estimate,Harmonic function,Half space http://bims.iranjournals.ir/article_479.html http://bims.iranjournals.ir/article_479_2cdf12321f02f3726af6042859a49ca3.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Investigation on the Hermitian matrix expression‎ ‎subject to some consistent equations 9 28 EN Xiang Zhang Department of Mathematics, Zunyi Normal College Shanghai Road, Zunyi 563000, P.R. China zxjnsc@163.com In 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. Linear matrix equation,Moore-Penrose inverse,rank,Inertia http://bims.iranjournals.ir/article_480.html http://bims.iranjournals.ir/article_480_368a4a67459524d7aa8a44355b07f8d1.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Coupled fixed point results for weakly related mappings in partially ordered metric spaces 29 40 EN Naval Singh govt. benazir college, bhopal drsinghnaval@gmail.com Reena Jain Technocrats Institute of technology reenakhatod@gmail.com In 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. Coupled fixed point,common coupled fixed point,partially ordered space,weakly related mappings http://bims.iranjournals.ir/article_481.html http://bims.iranjournals.ir/article_481_4e6a03a572aeff155f37a395d5757e77.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 ‎A matrix LSQR algorithm for solving constrained linear operator equations 41 53 EN Masoud Hajarian Department of Mathematics Faculty of Mathematical Sciences Shahid Beheshti University, G.C., Evin, Tehran 19839 Iran mhajarian@aut.ac.ir In 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. Iterative method,Bidiagonalization procedure,Linear operator equation http://bims.iranjournals.ir/article_482.html http://bims.iranjournals.ir/article_482_84ccde0152b76da6ba408ddf2be03cef.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Maximal prehomogeneous subspaces on classical groups 55 81 EN Xiaoxiang Yu Xuzhou Normal University, P.R.China carston123@126.com Dengyin Wang China University of Mining and technology wdengyin@126.com Suppose \$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. prehomogeneous space,adjoint action,orthogonal,symplectic,orbit http://bims.iranjournals.ir/article_483.html http://bims.iranjournals.ir/article_483_e3bd93459034ea5c23b49e16867e543d.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Sequential second derivative general linear methods for stiff systems 83 100 EN Ali Karam Ezzeddine University of Tabriz aliezz@tabrizu.ac.ir Gholamreza Hojjati University of Tabriz ghojjati@yahoo.com Ali Abdi University of Tabriz a_abdi@tabrizu.ac.ir ‎Second 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. General linear methods,Two--derivative methods,ordinary differential equation,Order conditions,A- and L-stability http://bims.iranjournals.ir/article_484.html http://bims.iranjournals.ir/article_484_e8bcd98926dd7174a8892e92e75c9438.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 On the numerical solution of generalized Sylvester matrix equations 101 113 EN Amer Kaabi iran kaabi_amer@kmsu.ac.ir ‎The 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. Generalized Sylvester matrix equations,Matrix Krylove subspace,Global gmres algorithm http://bims.iranjournals.ir/article_485.html http://bims.iranjournals.ir/article_485_1ba2c57bb65ad0afe866e7641b82604c.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 An extension theorem for finite positive measures on surfaces of finite‎ ‎dimensional unit balls in Hilbert spaces 115 124 EN Ahmad Reza Soltani Kuwait University and Shiraz University soltani@kuc01.kuniv.edu.kw Safieh Mahmoodi Isfahan University of Technology mahmoodi@cc.iut.ac.ir A 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). Extension Theorem,Separable Hilbert space,Finite Measures on Surfaces of the Unit Balls,Stable distribution,Spectral measure http://bims.iranjournals.ir/article_486.html http://bims.iranjournals.ir/article_486_e2f1c822857f6f622874900911e812f6.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Embedding measure spaces 125 155 EN M.R. Koushesh Isfahan University of Technology koushesh@cc.iut.ac.ir ‎For 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. Ultrafilter,thick subset,set of full outer measure,topological measure space,Baire measure,Stone--v{C}ech compactification,realcompactification http://bims.iranjournals.ir/article_487.html http://bims.iranjournals.ir/article_487_5d8ac1365f2e598525cbe53890ad515d.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 A class of Artinian local rings of homogeneous type 157 181 EN Leila Sharifan Hakim Sabzevari University, Sabzevar, Iran leilasharifan@gmail.com ‎Let \$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. artinian rings,Hilbert function,number of generators,Cohen-Macaulay type http://bims.iranjournals.ir/article_488.html http://bims.iranjournals.ir/article_488_46a770dbf68f66aa47bf6509eded267f.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Stochastic bounds for a single server queue with general retrial times 183 198 EN Mohamed Boualem University of Bejaia robertt15dz@yahoo.fr Natalia Djellab University of Annaba djellab@yahoo.fr Djamil Aïssani University of béjaia lamos_bejaia@hotmail.com We 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. Retrial queues,Markov chain,stochastic bounds,Monotonicity,ageing distributions http://bims.iranjournals.ir/article_489.html http://bims.iranjournals.ir/article_489_d8f721e663cfe851a582b1a8bde9e06e.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Existence and uniqueness of common coupled fixed point results via auxiliary functions 199 215 EN Sumit Chandok Khalsa College of Engineering & Technology (Punjab Technical University) chandhok.sumit@gmail.com Erdal Karapinar ATILIM UNIVERSITY erdalkarapinar@yahoo.com Mohammad Saeed Khan Sultan Qaboos University mohammad@squ.edu.om ‎The 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. Coupled coincidence point,ordered sets,Coupled fixed point,mixed monotone property http://bims.iranjournals.ir/article_490.html http://bims.iranjournals.ir/article_490_ff5cc3dca3e0121e2ecee853eea3a1ed.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Relative volume comparison theorems in Finsler geometry and their applications 217 234 EN Bing Ye Wu Department of Mathematics Minjiang University 569405943@qq.com We 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. extreme volume form,Finsler manifold,Gromov pre-compactness,first Betti number,fundamental group http://bims.iranjournals.ir/article_491.html http://bims.iranjournals.ir/article_491_a6a751d01b68cc3adc7d1c13f8010dc7.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 An eigenvalue study on the sufficient descent property of a‎ ‎modified Polak-Ribière-Polyak conjugate gradient method 235 242 EN Saman Babaie-Kafaki Semnan University sbk@semnan.ac.ir ‎Based 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. unconstrained optimization,Conjugate gradient algorithm,Sufficient descent condition,Eigenvalue http://bims.iranjournals.ir/article_492.html http://bims.iranjournals.ir/article_492_329f84fb9fa3da162a1ea3377a2c650e.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Various kinds of regular injectivity for \$S\$-posets 243 261 EN Leila Shahbaz University of Maragheh leilashahbaz@yahoo.com Mojgan Mahmoudi Shahid Beheshti University mojganmahmoudi@yahoo.com ‎In 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. \$S\$-poset,regular injective,weakly regular injective http://bims.iranjournals.ir/article_493.html http://bims.iranjournals.ir/article_493_ffd4d4411686956bba1a760f8c5969b5.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 Implicit iteration approximation for a‎ ‎finite family of asymptotically quasi-pseudocontractive type‎ ‎mappings 263 279 EN Shuyi Zhang Department of Mathematics, BoHai University jzzhangshuyi@126.com In 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. Normed linear spaces,implicit iteration process,asymptotically quasi-pseudocontractive type mappings,nonexpansive mappings http://bims.iranjournals.ir/article_494.html http://bims.iranjournals.ir/article_494_3783b5bd681d2f9f26ad8b170b0d7dba.pdf
Iranian Mathematical Society (IMS) Bulletin of the Iranian Mathematical Society 1017-060X 1735-8515 40 1 2014 02 01 On the norm of the derived‎ subgroups of all subgroups of a finite group 281 291 EN Zhencai Shen LMAM and School of Mathematical Sciences, Peking University, Beijing, 100871, China. zhencai688@sina.com Shirong Li Guangxi University shirong@sina.com Wujie Shi Chongqing University of Arts and Sciences shiwujie@outlook.com In 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. Derived subgroup,solvable group,nilpotency class,Fitting length http://bims.iranjournals.ir/article_495.html http://bims.iranjournals.ir/article_495_6dc0df68eafac1db15b433778ac7a5c1.pdf