2018-06-19T22:38:39Z
http://bims.iranjournals.ir/?_action=export&rf=summon&issue=64
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Bulletin of the Iranian Mathematical Society
2014
02
01
http://bims.iranjournals.ir/article_478_fab78335a362c9587481032ba27cf24c.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
A lower estimate of harmonic functions
Guoshuang
Pan
Lei
Qiao
Guantie
Deng
We shall give a lower estimate of harmonic functions of order greater than one in a half space, which generalize the result obtained by B. Ya. Levin in a half plane.
Lower estimate
Harmonic function
Half space
2014
02
01
1
7
http://bims.iranjournals.ir/article_479_2cdf12321f02f3726af6042859a49ca3.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Investigation on the Hermitian matrix expression subject to some consistent equations
Xiang
Zhang
In this paper, we study the extremal ranks and inertias of the Hermitian matrix expression $$ f(X,Y)=C_{4}-B_{4}Y-(B_{4}Y)^{*}-A_{4}XA_{4}^{*},$$ where $C_{4}$ is Hermitian, $*$ denotes the conjugate transpose, $X$ and $Y$ satisfy the following consistent system of matrix equations $A_{3}Y=C_{3}, A_{1}X=C_{1},XB_{1}=D_{1},A_{2}XA_{2}^{*}=C_{2},X=X^{*}.$ As consequences, we get the necessary and sufficient conditions for the above expression $f(X,Y)$ to be (semi) positive, (semi) negative. The relations between the Hermitian part of the solution to the matrix equation $A_{3}Y=C_{3}$ and the Hermitian solution to the system of matrix equations $A_{1}X=C_{1},XB_{1}=D_{1},A_{2}XA_{2}^{*}=C_{2}$ are also characterized. Moreover, we give the necessary and sufficient conditions for the solvability to the following system of matrix equations $A_{3}Y=C_{3},A_{1}X=C_{1},XB_{1}=D_{1}, A_{2}XA_{2}^{*}=C_{2},X=X^{*}, B_{4}Y+(B_{4}Y)^{*}+A_{4}XA_{4}^{*}=C_{4} $ and provide an expression of the general solution to this system when it is solvable.
Linear matrix equation
Moore-Penrose inverse
Rank
Inertia
2014
02
01
9
28
http://bims.iranjournals.ir/article_480_368a4a67459524d7aa8a44355b07f8d1.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Coupled fixed point results for weakly related mappings in partially ordered metric spaces
Naval
Singh
Reena
Jain
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
2014
02
01
29
40
http://bims.iranjournals.ir/article_481_4e6a03a572aeff155f37a395d5757e77.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
A matrix LSQR algorithm for solving constrained linear operator equations
Masoud
Hajarian
In this work, an iterative method based on a matrix form of LSQR algorithm is constructed for solving the linear operator equation $mathcal{A}(X)=B$ and the minimum Frobenius norm residual problem $||mathcal{A}(X)-B||_F$ 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 $textsf{R}^{rtimes s}$, $mathcal{G}$ is a linear self-conjugate involution operator and $Bin textsf{R}^{rtimes s}$. Numerical examples are given to verify the efficiency of the constructed method.
Iterative method
Bidiagonalization procedure
Linear operator equation
2014
02
01
41
53
http://bims.iranjournals.ir/article_482_84ccde0152b76da6ba408ddf2be03cef.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Maximal prehomogeneous subspaces on classical groups
Xiaoxiang
Yu
Dengyin
Wang
Suppose $G$ is a split connected reductive orthogonal or symplectic group over an infinite field $F,$ $P=MN$ is a maximal parabolic subgroup of $G,$ $frak{n}$ is the Lie algebra of the unipotent radical $N.$ Under the adjoint action of its stabilizer in $M,$ every maximal prehomogeneous subspaces of $frak{n}$ is determined.
prehomogeneous space
adjoint action
orthogonal
symplectic
orbit
2014
02
01
55
81
http://bims.iranjournals.ir/article_483_e3bd93459034ea5c23b49e16867e543d.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Sequential second derivative general linear methods for stiff systems
Ali
Ezzeddine
Gholamreza
Hojjati
Ali
Abdi
Second derivative general linear methods (SGLMs) as an extension of general linear methods (GLMs) have been introduced to improve the stability and accuracy properties of GLMs. The coefficients of SGLMs are given by six matrices, instead of four matrices for GLMs, which are obtained by solving nonlinear systems of order and usually Runge--Kutta stability conditions. In this paper, we introduce a technique for construction of an special case of SGLMs which decreases the complexity of finding coefficients matrices.
General linear methods
Two--derivative methods
ordinary differential equation
Order conditions
A- and
L-stability
2014
02
01
83
100
http://bims.iranjournals.ir/article_484_e8bcd98926dd7174a8892e92e75c9438.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
On the numerical solution of generalized Sylvester matrix equations
Amer
Kaabi
The global FOM and GMRES algorithms are among the effective methods to solve Sylvester matrix equations. In this paper, we study these algorithms in the case that the coefficient matrices are real symmetric (real symmetric positive definite) and extract two CG-type algorithms for solving generalized Sylvester matrix equations. The proposed methods are iterative projection methods onto matrix Krylov subspaces. Numerical examples are presented.
Generalized Sylvester matrix equations
Matrix Krylove subspace
Global gmres algorithm
2014
02
01
101
113
http://bims.iranjournals.ir/article_485_1ba2c57bb65ad0afe866e7641b82604c.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
An extension theorem for finite positive measures on surfaces of finite dimensional unit balls in Hilbert spaces
Ahmad Reza
Soltani
Safieh
Mahmoodi
A consistency criteria is given for a certain class of finite positive measures on the surfaces of the finite dimensional unit balls in a real separable Hilbert space. It is proved, through a Kolmogorov type existence theorem, that the class induces a unique positive measure on the surface of the unit ball in the Hilbert space. As an application, this will naturally accomplish the work of Kanter (1973) on the existence and uniqueness of the spectral measures of finite dimensional stable random vectors to the infinite dimensional ones. The approach presented here is direct and different from the functional analysis approach in Kuelbs (1973), Linde (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
2014
02
01
115
124
http://bims.iranjournals.ir/article_486_e2f1c822857f6f622874900911e812f6.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Embedding measure spaces
M.R.
Koushesh
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
2014
02
01
125
155
http://bims.iranjournals.ir/article_487_5d8ac1365f2e598525cbe53890ad515d.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
A class of Artinian local rings of homogeneous type
Leila
Sharifan
Let $I$ be an ideal in a regular local ring $(R,n)$, we will find bounds on the first and the last Betti numbers of $(A,m)=(R/I,n/I)$. if $A$ is an Artinian ring of the embedding codimension $h$, $I$ has the initial degree $t$ and $mu(m^t)=1$, we call $A$ a {it $t-$extended stretched local ring}. This class of 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, we show that ${h+t-2choose t-1}-h+1leq tau(A)leq {h+t-2choose t-1}$ and $ {h+t-1choose t}-1 leq mu(I) leq {h+t-1choose t}$. Moreover $tau(A)$ reaches the upper bound if and only if $mu(I)$ is the maximum value. Using these results, we show when $beta_i(A)=beta_i(gr_m(A))$ for each $igeq 0$. Beside, we will investigate the rigid behavior of the Betti numbers of $A$ in the case that $I$ has initial degree $t$ and $mu(m^t)=2$. This class is a natural generalization of {it almost stretched local rings} again studied by Elias and Valla. Our research extends several results of two papers by Rossi, Elias and Valla.
artinian rings
Hilbert function
number of
generators
Cohen-Macaulay type
2014
02
01
157
181
http://bims.iranjournals.ir/article_488_46a770dbf68f66aa47bf6509eded267f.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Stochastic bounds for a single server queue with general retrial times
Mohamed
Boualem
Natalia
Djellab
Djamil
Aïssani
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
2014
02
01
183
198
http://bims.iranjournals.ir/article_489_d8f721e663cfe851a582b1a8bde9e06e.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Existence and uniqueness of common coupled fixed point results via auxiliary functions
Sumit
Chandok
Erdal
Karapinar
Mohammad Saeed
Khan
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
2014
02
01
199
215
http://bims.iranjournals.ir/article_490_ff5cc3dca3e0121e2ecee853eea3a1ed.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Relative volume comparison theorems in Finsler geometry and their applications
Bing Ye
Wu
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
2014
02
01
217
234
http://bims.iranjournals.ir/article_491_a6a751d01b68cc3adc7d1c13f8010dc7.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
An eigenvalue study on the sufficient descent property of a modified Polak-Ribière-Polyak conjugate gradient method
Saman
Babaie-Kafaki
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
2014
02
01
235
242
http://bims.iranjournals.ir/article_492_329f84fb9fa3da162a1ea3377a2c650e.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Various kinds of regular injectivity for $S$-posets
Leila
Shahbaz
Mojgan
Mahmoudi
In this paper some properties of weak regular injectivity for $S$-posets, where $S$ is a pomonoid, are studied. The behaviour of different kinds of weak regular injectivity with products, coproducts and direct sums is considered. Also, some characterizations of pomonoids over which all $S$-posets are of some kind of weakly regular injective are obtained. Further, we give some Baer conditions which state the relation among some kinds of weak regular injectivity.
$S$-poset
regular injective
weakly regular injective
2014
02
01
243
261
http://bims.iranjournals.ir/article_493_ffd4d4411686956bba1a760f8c5969b5.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Implicit iteration approximation for a finite family of asymptotically quasi-pseudocontractive type mappings
Shuyi
Zhang
In this paper, strong convergence theorems of Ishikawa type implicit iteration process with errors for a finite family of asymptotically nonexpansive in the intermediate sense and asymptotically quasi-pseudocontractive type mappings in normed linear spaces are established by using a new analytical method, which essentially improve and extend some recent results obtained by Yang [Convergence theorems of implicit iteration process for asymptotically pseudocontractive mappings, Bulletin of the Iranian Mathematical Society, Available Online from 12 April 2011] and others.
Normed linear spaces
implicit iteration process
asymptotically quasi-pseudocontractive type mappings
nonexpansive mappings
2014
02
01
263
279
http://bims.iranjournals.ir/article_494_3783b5bd681d2f9f26ad8b170b0d7dba.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
On the norm of the derived subgroups of all subgroups of a finite group
Zhencai
Shen
Shirong
Li
Wujie
Shi
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 subgroups of a finite group, J. Algebra, 323 (2010) 1349--1357]. In addition, we also give a generalization of Baer's Theorem.
Derived subgroup
solvable group
nilpotency class
Fitting length
2014
02
01
281
291
http://bims.iranjournals.ir/article_495_6dc0df68eafac1db15b433778ac7a5c1.pdf
Bulletin of the Iranian Mathematical Society
BIMS
1017-060X
1017-060X
2014
40
1
Letter of Retraction
2014
02
01
293
293
http://bims.iranjournals.ir/article_496_40e870ab09cf622e824b151176739b44.pdf