Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Common fixed points of f-weak contractions in cone metric spaces
293
303
EN
Wultipol
Sintunavarat
King Mongkut's University of Technology Thonburi (KMUTT)
poom_teun@hotmail.com
Poom
Kumam
King Mongkut's University of Technology Thonburi (KMUTT)
poom.kum@kmutt.ac.th
Recently, Choudhury and Metiya [Fixed points of weak contractions in cone metric spaces, Nonlinear Analysis 72 (2010) 1589-1593] proved some fixed point theorems for weak contractions in cone metric spaces. Weak contractions are generalizations of the Banach's contraction mapping, which have been studied by several authors. In this paper, we introduce the notion of $f$-weak contractions and also establish a coincidence and common fixed point result for $f$-weak contractions in cone metric spaces. Our result is supported by an example which include and generalize the results of Choudhury and Metiya's work.
Cone metric spaces,Weak contraction,f-weak
contraction,coincidence point,common fixed point
http://bims.iranjournals.ir/article_218.html
http://bims.iranjournals.ir/article_218_d595625aa45af7f415864e2b1458807a.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Rings with a setwise polynomial-like condition
305
311
EN
Ali
Tavakoli
Islamic Azad University - Majlesi Branch
ali_tavakoli_targhi@yahoo.com
Alireza
Abdollahi
University of Isfahan
a.abdollahi@math.ui.ac.ir
Howard E.
Bell
Brock University
hbell@brocku.ca
Let $R$ be an infinite ring. Here we prove that if $0_R$ belongs to ${x_1x_2cdots x_n ;|; x_1,x_2,dots,x_nin X}$ for every infinite subset $X$ of $R$, then $R$ satisfies the polynomial identity $x^n=0$. Also we prove that if $0_R$ belongs to ${x_1x_2cdots x_n-x_{n+1} ;|; x_1,x_2,dots,x_n,x_{n+1}in X}$ for every infinite subset $X$ of $R$, then $x^n=x$ for all $xin R$.
Primitive rings,Polynomial identities,Combinatorial conditions
http://bims.iranjournals.ir/article_231.html
http://bims.iranjournals.ir/article_231_c96d633637c016b61c15d2693daeeffb.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
A new family in the stable homotopy groups of spheres
313
322
EN
Xiugui
Liu
School of Mathematical Sciences and LPMC,
Nankai University,
Tianjin 300071,
P. R China
xgliu@nankai.edu.cn
Kai
Ma
Mathematics and Information
Science College,Hebei Normal University, 050016,Shijiazhuang, P. R. China
kai-ma@163.com
Let $p$ be a prime number greater than three. In this paper, we prove the existence of a new family of homotopy elements in the stable homotopy groups of spheres $pi_{ast}(S)$ which is represented by $h_nh_mtilde{beta}_{s+2}in {rm Ext}_A^{s+4, q[p^n+p^m+(s+2)p+(s+1)]+s}(mathbb{Z}_p,mathbb{Z}_p)$ up to nonzero scalar in the Adams spectral sequence, where $ngeq m+2>5$, $0leq sExt}_A^{s+2,q[(s+2)p+(s+1)]+s}(mathbb{Z}_p,mathbb{Z}_p)$ was defined by X. Wang and Q. Zheng.
stable homotopy groups of spheres,Adams spectral
sequence,May spectral sequence
http://bims.iranjournals.ir/article_204.html
http://bims.iranjournals.ir/article_204_3e0a128f7a5b367bd3351fe6549af39e.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Branches in random recursive k-ary trees
323
331
EN
Mehri
Javanian
Javanian
javanian_m@yahoo.com
Mohammad Q.
Vahidi Asl
Vahidi-Asl
m-vahidi@sbu.ac.ir
In this paper, using generalized {polya} urn models we find the expected value of the size of a branch in recursive $k$-ary trees. We also find the expectation of the number of nodes of a given outdegree in a branch of such trees.
trees,random recursive trees,generalized
P'olya urn models
http://bims.iranjournals.ir/article_200.html
http://bims.iranjournals.ir/article_200_0fb18b5d341305095aa3c67a34c101b0.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Horvitz-Thompson estimator of population mean under inverse sampling designs
333
347
EN
Mohammad
Mohammadi
School of Mathematical Science, Isfahan University of Technology, Isfahan, Iran.
m.mohammadi@sci.ui.ac.ir
Mohammad
Salehi Marzijarani
Department of Mathematical Sciences, Isfahan University of Technology 84156-83111, Iran;
Department of Mathematics, Statistics and Physics, Qatar University, P.O.Box 2713, Doha, Qatar.
salehi_m@cc.iut.ac.ir
Inverse sampling design is generally considered to be appropriate technique when the population is divided into two subpopulations, one of which contains only few units. In this paper, we derive the Horvitz-Thompson estimator for the population mean under inverse sampling designs, where subpopulation sizes are known. We then introduce an alternative unbiased estimator, corresponding to post-stratification approach. Both of these are not location-invariant, but this is ignorable for alternative estimator. Using a simulation study, we find that Horvitz-Thompson estimator is an efficient estimator when the mean of the off-interest subpopulation is close to zero while the alternative estimator appears to be an efficient estimator in general.
Finite Population,Inverse Sampling,Post-stratification,Random Sample Size
http://bims.iranjournals.ir/article_255.html
http://bims.iranjournals.ir/article_255_8bc393a21f635d83fc2a4bdda66f1e39.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Comparison results on the preconditioned mixed-type splitting
iterative method for M-matrix linear systems
349
367
EN
M.
Mohseni Moghadam
Shahid Bahonar University of Kerman
mohseni@mail.uk.ac.ir
Fatemeh
Panjeh Ali Beik
Vali-Asr University of Rafsanjan
f.beik@vru.ac.ir
Consider the linear system Ax=b where the coefficient matrix A is an M-matrix. In the present work, it is proved that the rate of convergence of the Gauss-Seidel method is faster than the mixed-type splitting and AOR (SOR) iterative methods for solving M-matrix linear systems. Furthermore, we improve the rate of convergence of the mixed-type splitting iterative method by applying a preconditioned matrix. Comparison theorems show that the rate of convergence of the preconditioned Gauss-Seidel method is faster than the preconditioned mixed-type splitting and AOR (SOR) iterative methods. Finally, some numerical examples are presented to illustrate the reality of our comparison theorems.
Linear systems,Mixed-type splitting iterative method,Preconditioned matrix,M-matrix
http://bims.iranjournals.ir/article_211.html
http://bims.iranjournals.ir/article_211_dc5b9e9e1b2a179a471b622100c26a58.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
An iterative method for amenable semigroup and infinite family of non expansive mappings
in Hilbert spaces
369
389
EN
Husain
Piri
Department of Mathematics, Bonab Higher Education Complex
husain.piri@gmail.com
Hamid
Vaezi
Faculty of Mathematical Sciences University
of Tabriz, Tabriz, Iran
hvaezi@tabrizu.ac.ir
begin{abstract} In this paper, we introduce an iterative method for amenable semigroup of non expansive mappings and infinite family of non expansive mappings in the frame work of Hilbert spaces. We prove the strong convergence of the proposed iterative algorithm to the unique solution of a variational inequality, which is the optimality condition for a minimization problem. The results presented in this paper mainly extend the corresponding results announced by Qin et al. [X. Qin, Y. J. Cho, and S. M. Kang, An iterative method for an infinite family of non-expansive mappings in Hilbert spaces, Bull. Malays. Math. Sci. Soc. 32 (2009) 161-171] and many others. end{abstract}
common fixed point,strong convergence,Amenable
semigroup
http://bims.iranjournals.ir/article_207.html
http://bims.iranjournals.ir/article_207_7d5d8ff16fbbbca2e1790a0f9ab74c87.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2011
02
23
Recurrent metrics in the geometry of second order differential equations
391
401
EN
Mircea
Crasmareanu
Faculty of Mathematics
University "Al. I. Cuza"
Iasi, 700506
mcrasm@uaic.ro
Given a pair (semispray $S$, metric $g$) on a tangent bundle, the family of nonlinear connections $N$ such that $g$ is recurrent with respect to $(S, N)$ with a fixed recurrent factor is determined by using the Obata tensors. In particular, we obtain a characterization for a pair $(N, g)$ to be recurrent as well as for the triple $(S, stackrel{c}{N}, g)$ where $stackrel{c}{N}$ is the canonical nonlinear connection of the semispray $S$. Also, the Weyl connection of conformal gauge theories is obtained as a particular case.
Semispray,nonlinear connection,recurrent metric,Obata operators
http://bims.iranjournals.ir/article_215.html
http://bims.iranjournals.ir/article_215_dcd58d4931f7da614e2cbc66aa27cade.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Projective maximal submodules of extending regular modules
403
412
EN
E.
Momtahan
Yasouj University
We show that a projective maximal submodule of afinitely generated, regular, extending module is a directsummand. Hence, every finitely generated, regular, extendingmodule with projective maximal submodules is semisimple. As aconsequence, we observe that every regular, hereditary, extendingmodule is semisimple. This generalizes and simplifies a result of Dung and Smith. As another consequence, we observe thatevery right continuous ring, whose maximal right ideals areprojective, is semisimple Artinian. This generalizes some resultsof Osofsky and Karamzadeh. We also observe thatfour classes of rings, namely right $aleph_0$-continuous rings,right continuous rings, right $aleph_0$-continuous regular ringsand right continuous regular rings are not axiomatizable.
continuous rings,extending rings,regular
rings,\aleph_0-self-injective rings
http://bims.iranjournals.ir/article_407.html
http://bims.iranjournals.ir/article_407_6a4d7f84d031275eb5d254f9f2871b8d.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Finite p-groups with few non-linear irreducible character kernels
413
422
EN
Hossein
Doostie
Tarbiat Moallem University
doostih@tmu.as.ir
Amin
Saeidi
Tarbiat Moallem University
saeidi.amin@gmail.com
Abstract. In this paper, we classify all of the ﬁnite p-groups with at most three non linear irreducible character kernels.
Minimal normal subgroups,few character kernels,strong and weak conditions
http://bims.iranjournals.ir/article_208.html
http://bims.iranjournals.ir/article_208_69f56c704b32022bc49cb06797e62448.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Invariance of the barycentric subdivision of a simplicial complex
423
432
EN
Rashid
Zaare-Nahandi
Institute for Advanced Studies in Basic Sciences
rashidzn@iasbs.ac.ir
In this paper we prove that a simplicial complex is determined uniquely up to isomorphism by its barycentric subdivision as well as its comparability graph. We also put together several algebraic, combinatorial and topological invariants of simplicial complexes.
Simplicial complex,comparability graph,barycentric subdivision
http://bims.iranjournals.ir/article_212.html
http://bims.iranjournals.ir/article_212_de5bc8c7b7b3dc3bfb85ee068f5d21f6.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
On Rickart modules
433
445
EN
S
Agayev
Eropean University of Lefke, Cyprus
S
Halicioglu
Department of Mathematics
Ankara University
halici@ankara.edu.tr
A
Harmanci
Hacettepe University, Turkey
Let $R$ be an arbitrary ring with identity and $M$ a right $R$-module with $S=$ End$_R(M)$. The module $M$ is called {it Rickart} if for any $fin S$, $r_M(f)=Se$ for some $e^2=ein S$. We prove that some results of principally projective rings and Baer modules can be extended to Rickart modules for this general settings.
Rickart modules,Baer modules,reduced
modules,rigid modules
http://bims.iranjournals.ir/article_209.html
http://bims.iranjournals.ir/article_209_a482f3c0119843e2d96bfda7f6af9907.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Optimal order finite element approximation for a hyperbolic integro-differential equation
447
459
EN
Fardin
Saedpanah
University of Kurdistan,
Department of Mathematics
f_saedpanah@yahoo.com
Semidiscrete finite element approximation of a hyperbolic type integro-differential equation is studied. The model problem is treated as the wave equation which is perturbed with a memory term. Stability estimates are obtained for a slightly more general problem. These, based on energy method, are used to prove optimal order a priori error estimates.
finite element method,wave equation,
integro-differential equation,Stability,a priori error estimate
http://bims.iranjournals.ir/article_201.html
http://bims.iranjournals.ir/article_201_e72a83b9b71c31f92537ef2e58b72810.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Properties of multivalent functions associated with certain integral operator
461
468
EN
Jin-Lin
Liu
Department of Mathematics, Yangzhou University
jlliu@yzu.edu.cn
Let A(p) denote the class of functions which are analytic in the open unit disk U. By making use of certain integral operator,we obtain some interesting properties of multivalent analytic functions.
Multivalent function,analytic function,integral operator
http://bims.iranjournals.ir/article_198.html
http://bims.iranjournals.ir/article_198_05b363674deba2ef06e6925dc08db279.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Applications of epi-retractable modules
469
477
EN
Bashishth
Muni
Pandeya
Department of Applied Mathematics, Institute of Technology, Banaras Hindu University,
Varanasi-221005, India.
bmpandeya@bhu.ac.in
Avanish
Kumar
Chaturvedi
Department of Mathematics, Jaypee Institute of Information Technology,
(Deemed University) A-10, Sector-62, Noida-201307 (UP), India
akc99@rediffmail.com
Ashok
Ji
Gupta
Department of Applied Mathematics, Institute of Technology, Banaras Hindu University,
Varanasi-221005, India.
ashokg@bhu.ac.in
An R-module M is called epi-retractable if every submodule of MR is a homomorphic image of M. It is shown that if R is a right perfect ring, then every projective slightly compressible module MR is epi-retractable. If R is a Noetherian ring, then every epi-retractable right R-module has direct sum of uniform submodules. If endomorphism ring of a module MR is von-Neumann regular, then M is semi-simple if and only if M is epi-retractable. If R is a quasi Frobenius ring, then R is a right hereditary ring if and only if every injective right R-module is semi-simple. A ring R is semi-simple if and only if R is right hereditary and every epiretractable right R-module is projective. Moreover, a ring R is semi-simple if and only if R is a pri and von-Neumann regular.
Epi-retractable modules,semi-simple rings,Perfect rings,Hereditary rings,von-Numann regular rings
http://bims.iranjournals.ir/article_202.html
http://bims.iranjournals.ir/article_202_388757ddee7a3a67ab050c9a998e2049.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Some vector fields on a riemannian manifold with semi-symmetric metric connection
479
490
EN
Füsun
Özen Zengin
Istanbul Technical University
fozen@itu.edu.tr
Sezgin
Altay Demirbag
Istanbul Technical University
saltay@itu.edu.tr
S. Aynur
Uysal
Dogus University
auysal@dogus.edu.tr
Hülya
Bagdatli Yilmaz
Marmara University
hbagdatli@marmara.edu.tr
In the first part of this paper, some theorems are given for a Riemannian manifold with semi-symmetric metric connection. In the second part of it, some special vector fields, for example, torse-forming vector fields, recurrent vector fields and concurrent vector fields are examined in this manifold. We obtain some properties of this manifold having the vectors mentioned above.
Semi-symmetric metric connection,sectional curvature,conformally flat manifold,pseudo symmetric manifold,concircular
vector field
http://bims.iranjournals.ir/article_203.html
http://bims.iranjournals.ir/article_203_231ecca82cd01017b92531f34000f4d6.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Riordan group approaches in matrix factorizations
491
506
EN
Emrah
Kilic
TOBB University of Economics and Technology Mathematics Department
ekilic@etu.edu.tr
Nese
Omur
Kocaeli University Mathematics Department
neseomur@kocaeli.edu.tr
Gulfer
Tatar
Kocaeli University Mathematics Department
gulfera@kocaeli.edu.tr
In this paper, we consider an arbitrary binary polynomial sequence {A_n} and then give a lower triangular matrix representation of this sequence. As main result, we obtain a factorization of the innite generalized Pascal matrix in terms of this new matrix, using a Riordan group approach. Further some interesting results and applications are derived.
Riordan Group,Factorization,Binary Recurrences,Pascal Matrix
http://bims.iranjournals.ir/article_205.html
http://bims.iranjournals.ir/article_205_da5f4f10d7f10a4b73c7db3f21ccb967.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Some homological properties of amalgamated duplication of a ring along an ideal
507
515
EN
Mohamed
Chhiti
University of Fez, Fez, Morocco
chhiti.med@hotmail.com
Najib
Mahdou
Department of Mathematics, Faculty of Sciences and Technology, University of Fez, Fez, Morocco.
mahdou@hotmail.com
In this work, we investigate the transfer of some homological properties from a ring $R$ to its amalgamated duplication along some ideal $I$ of $R$ $Rbowtie I$, and then generate new and original families of rings with these properties.
Amalgamated,Perfect ring,(n,d)-ring
http://bims.iranjournals.ir/article_210.html
http://bims.iranjournals.ir/article_210_485789e3f153661d4d8c1136c73cb0d1.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
A note on the socle of certain types of f-rings
517
528
EN
Themba
Dube
University of South Africa
tdube2013@yahoo.co.za
For any reduced commutative $f$-ring with identity and bounded inversion, we show that a condition which is obviously necessary for the socle of the ring to coincide with the socle of its bounded part, is actually also sufficient. The condition is that every minimal ideal of the ring consist entirely of bounded elements. It is not too stringent, and is satisfied, for instance, by rings of continuous functions.
frame,function rings,ideal,socle
http://bims.iranjournals.ir/article_214.html
http://bims.iranjournals.ir/article_214_3c1783bf3988903f43f20700e3e575bc.pdf
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
38
2
2012
07
15
Ring structures of mod p equivariant cohomology rings and ring homomorphisms between them
529
542
EN
Yanchang
Chen
College of Mathematics and Information Science, Hebei Normal University, Yuhua
Road 113, Shijiazhuang 050016, P. R. China
cyc810707@163.com
Yanying
Wang
College of Mathematics and Information Science, Hebei Normal University, Yuhua Road 113, Shijiazhuang 050016, P. R. China
wyanying2003@yahoo.com.cn
In this paper, we consider a class of connected oriented (with respect to Z/p) closed G-manifolds with a non-empty finite fixed point set, each of which is G-equivariantly formal, where G = Z/p and p is an odd prime. Using localization theorem and equivariant index, we give an explicit description of the mod p equivariant cohomology ring of such a G-manifold in terms of algebra. This makes it possible to determine the number of equivariant cohomology rings (up to isomorphism) of such 2-dimensional G-manifolds. Moreover, we obtain a description of the ring homomorphism between equivariant cohomology rings of such two G-manifolds induced by a G-equivariant map, and show a characterization of the ring homomorphism.
G-manifold,equivariant index,equivariant cohomology,ring homomorphism
http://bims.iranjournals.ir/article_217.html
http://bims.iranjournals.ir/article_217_d78bd5727580f199e3b327f8189d5d8a.pdf