eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-10-15
37
No. 3
1
9
347
A characterization of shellable and sequentially Cohen-Macaulay
S. Moradi
s-moradi@araku.ac.ir
1
D. Kiani
dkiani@aut.ac.ir
2
Amirkabir University of Technology
Amirkabir University of Technology
We consider a class of hypergraphs called
hypercycles and we show that a hypercycle $C_n^{d,alpha}$ is
shellable or sequentially the Cohen--Macaulay if and only if
$nin{3,5}$. Also, we characterize Cohen--Macaulay hypercycles.
These results are hypergraph versions of results proved for cycles
in graphs.
http://bims.iranjournals.ir/article_347_7a249698165516accceec04e5a5ba578.pdf
Edge ideals
shellable complex
sequentially Cohen-Macaulay ring
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
11
20
348
Non-linear ergodic theorems in complete non-positive curvature metric spaces
B. Ahmadi Kakavandi
1
M. Amini
mamini48@yahoo.com
2
Tarbiat Modares University
Tarbiat Modares University
Hadamard (or complete $CAT(0)$) spaces are complete, non-positive curvature, metric spaces. Here,
we prove a nonlinear ergodic theorem for continuous non-expansive semigroup in these spaces as well as a strong convergence theorem for
the commutative case. Our results extend the standard non-linear
ergodic theorems for non-expansive maps on real Hilbert spaces,
to non-expansive maps on Hadamard spaces, which include for example (possibly infinite-dimensional) complete simply
connected Riemannian manifolds with non-positive sectional
curvature.
http://bims.iranjournals.ir/article_348_bd937fd396e4bfd643f273cb0f5b9aed.pdf
Hadamard Space
continuous non-expansive semigroup
invariant mean
asymptotic center
non-linear ergodic theorem
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
21
32
349
A characterization of L-dual frames and L-dual Riesz bases
A. Ahmadi
1
A. Askari Hemmat
2
This paper is an investigation of $L$-dual frames with respect
to a function-valued inner product, the so called $L$-bracket
product on $L^{2}(G)$, where G is a locally compact abelian group
with a uniform lattice $L$. We show that several well known theorems
for dual frames and dual Riesz bases in a Hilbert space
remain valid for $L$-dual frames and $L$-dual Riesz bases in $L^{2}(G)$.
http://bims.iranjournals.ir/article_349_e505bfd0f796940777bc05b6fd51c8f5.pdf
Hyers-Ulam-Rassias stability
generalized
derivation
bounded central approximate identity
faithful Banach
algebra
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2012-09-15
37
No. 3
33
37
350
On rainbow 4-term arithmetic progressions
M. H. Shirdareh Haghighi
1
P. Salehi Nowbandegani
2
{sl Let $[n]={1,dots, n}$ be colored in $k$ colors. A rainbow
AP$(k)$ in $[n]$ is a $k$ term arithmetic progression whose
elements have different colors. Conlon, Jungi'{c} and
Radoiv{c}i'{c} cite{conlon} prove that there exists an
equinumerous 4-coloring of $[4n]$ which is rainbow AP(4) free,
when $n$ is even. Based on their construction, we show that such
a coloring of $[4n]$
also exists for odd $n>1$.
We conclude that for nonnegative integers $kgeq 3$
and $n > 1$, every equinumerous $k$-coloring of $[kn]$ contains a
rainbow AP$(k)$ if and only if $k=3$.}
http://bims.iranjournals.ir/article_350_89e63dba5b5df3fefe16dd3a01425b8e.pdf
Rainbow arithmetic progression
4-term arithmetic progression
AP(4)
AP($k$)
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
39
75
352
Second symmetric powers of chain complexes
A. Frankild
1
S. Sather-Wagstaff
2
A. Taylor
3
We investigate Buchbaum and Eisenbud's construction of the second
symmetric power $s_R(X)$ of a chain complex $X$ of modules over
a commutative ring $R$. We state and prove a number of results
from the folklore of the subject for which we know of no good
direct references. We also provide several explicit computations
and examples. We use this construction to prove the following
version of a result of Avramov, Buchweitz, and c{S}ega: let
$Rto S$ be a module-finite ring homomorphism such that $R$ is
noetherian and local, and such that 2 is a unit in $R$. Let $X$
be a complex of finite rank free $S$-modules such that $X_n=0$
for each $n<0$. If
$cup_nass_R(HH_n(Xotimes_SX))subseteqass(R)$ and if
$X_{p}simeq S_{p}$ for each $pinass(R)$, then $Xsimeq S$.
http://bims.iranjournals.ir/article_352_3993b9c37fc0e81314ac0cd20be606cf.pdf
Chain complex
symmetric power
symmetric square
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2012-09-15
37
No. 3
77
108
351
General Hardy-Type Inequalities with Non-conjugate Exponents
A. Cizmesija
1
M. Krnic
2
J. Pecaric
3
We derive whole series of new integral
inequalities of the Hardy-type, with non-conjugate exponents.
First, we prove and discuss two equivalent general
inequa-li-ties of such type, as well as their corresponding
reverse inequalities. General results are then applied to special
Hardy-type kernel and power weights. Also, some estimates of
weight functions and constant factors are obtained. In
particular, we obtain generalizations and improvements of some
recent results, in the literature.
http://bims.iranjournals.ir/article_351_52e9e19972fed6970fe01efd0a82b904.pdf
Hardy inequality
Hilbert inequality
Hardy-type kernel
Hardy-type inequality
Hilbert-type inequality
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
109
115
353
Some Optimal Codes From Designs
M. Emami
1
Ch. Maysoori
2
The binary and ternary codes spanned by the rows of the point by
block incidence matrices of some 2-designs and their
complementary
and orthogonal designs are studied. A new method is also introduced to study optimal codes.
http://bims.iranjournals.ir/article_353_1c31d56b10fe384966174ee83e0eb049.pdf
Optimal code
t-design
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
117
134
354
Extension functors of local cohomology modules
M. Aghapournahr
1
A. Taherizadeh
2
A. Vahidi
3
Let $R$ be a commutative Noetherian ring with non-zero identity,
$fa$ an ideal of $R$, and $X$ an $R$--module. Here, for fixed
integers $s, t$ and a finite $fa$--torsion $R$--module $N$, we
first study the membership of $Ext^{s+t}_{R}(N, X)$ and
$Ext^{s}_{R}(N, H^{t}_{fa}(X))$ in the Serre subcategories of
the category of $R$--modules. Then, we present some conditions
which ensure the existence of an isomorphism between them.
Finally, we introduce the concept of the Serre cofiniteness as a
generalization of cofiniteness and study this property for
certain local cohomology modules.
http://bims.iranjournals.ir/article_354_a36964c381b38b75e5e066579630220a.pdf
Local cohomology modules
Serre subcategories
cofinite
modules
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
135
148
355
Convergence of product integration method applied for numerical
solution of linear weakly singular Volterra
systems
B. Babayar-Razlighi
Babayar@tabrizu.ac.ir
1
K. Ivaz
2
M. Mokhtarzadeh
3
We develop and apply the product integration method to a large class of linear weakly singular Volterra
systems. We show that under certain sufficient conditions this
method converges. Numerical implementation of the method is
illustrated by a benchmark problem originated from heat
conduction.
http://bims.iranjournals.ir/article_355_4c05419e0679e03a7d612b134a6c9404.pdf
Product integration technique
system of singular Volterra integral equations
heat equation
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
149
157
356
On Semi-artinian Weakly Co-semisimple Modules
E. Momtahan
1
We show that every semi-artinian module which is contained in a
direct sum of
finitely presented modules in $si[M]$, is weakly co-semisimple if and only if it is regular in $si[M]$.
As a consequence, we observe that every
semi-artinian ring is regular in the sense of von Neumann if
and only if its simple modules are $FP$-injective.
http://bims.iranjournals.ir/article_356_cf010bff12b9e95965d9ffb69052de01.pdf
Semi-artinian module
weakly co-semisimple module
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
159
170
357
Various topological forms of Von Neumann regularity in Banach algebras
G. Esslamzadeh
1
M. Shadab
2
We study topological von Neumann regularity
and principal von Neumann regularity of Banach algebras. Our
main objective is comparing these two types of Banach algebras and
some other known Banach algebras with one another. In particular,
we show that the class of topologically von Neumann regular Banach
algebras contains all $C^*$-algebras, group algebras of compact
abelian groups and certain weakly amenable Banach algebras while
it excludes measure algebras, of certain locally compact Abelian
groups. Moreover, we show that in a unital amenable Banach
algebra, principal regularity implies topological regularity.
Finally, we use topological regularity to obtain some information
about hereditary $C^*$-subalgebras of a given $C^*$-algebra.
http://bims.iranjournals.ir/article_357_bceaa5c7dfeb6e2303668f1f6eee51b4.pdf
Topologically von Neumann regular
principally von Neumann regular
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
171
181
358
Insertion of a gamma-continuous function
M. Mirmiran
1
A necessary and sufficient condition in terms of lower cut sets
are given for the insertion of a $gamma-$continuous function
between two comparable real-valued functions.
http://bims.iranjournals.ir/article_358_585a7ccdab5fde974ec45e285e1cc82f.pdf
Insertion
strong binary relation
preopen set
semi-open set
$gamma-$open set
lower cut set
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
183
195
359
Monomial Irreducible sln-Modules
M. Shahryari
1
In this article, we introduce monomial irreducible representations of the special linear Lie
algebra $sln$. We will show that this kind of representations have bases for
which the action of the Chevalley generators of the Lie algebra on the basis elements
can be given by a simple formula.
http://bims.iranjournals.ir/article_359_c314a69d352fa6f7d05794e57d93f5e2.pdf
symmetric group
character theory
representations of Lie algebras
symmetry classes of tensors
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
197
215
360
Permanence and global asymptotic stability of a delayed
predator-prey model with Hassell-Varley type functional response
K. Wang
1
Y. Zhu
2
Here, a predator-prey model with Hassell-Varley type functional
responses is studied. Some sufficient conditions are obtained
for the permanence and global asymptotic stability of the
system by using comparison theorem and constructing a suitable
Lyapunov functional. Moreover, an example is illustrated to
verify the results by simulation.
http://bims.iranjournals.ir/article_360_e5991d60269c657b39ab2541a80032d9.pdf
Permanence
asymptotic stability
comparison theorem
Lyapunov functional
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
217
233
361
Semistar dimension of polynomial rings and Prufer-like
domains
P. Sahandi
1
Let $D$ be an integral domain and $star$ a semistar operation stable and of finite type on
it. We define the semistar dimension (inequality) formula and
discover their relations with $star$-universally catenarian
domains and $star$-stably strong S-domains. As an application, we
give new characterizations of $star$-quasi-Pr"{u}fer domains
and UM$t$ domains in terms of dimension inequality formula (and
the notions of universally catenarian domain, stably strong
S-domain, strong S-domain, and Jaffard domain). We also extend
Arnold's formula to the setting of semistar operations.
http://bims.iranjournals.ir/article_361_6dbe9e5fa7817562fab715a62353d061.pdf
Semistar operation
Krull dimension
strong S-domain
Jaffard domain
quasi-Pr"{u}fer domain
UM$t$ domain
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
235
248
362
A Sharp Maximal Function Estimate for Vector-Valued Multilinear
Singular Integral Operator
Zhou Xiaosha
1
Liu Lanzhe
lanzheliu@163.com
2
We establish a sharp maximal function estimate for some vector-valued multilinear singular integral operators.
As an application, we obtain the $(L^p, L^q)$-norm inequality for vector-valued multilinear operators.
http://bims.iranjournals.ir/article_362_3e71d982083b4f407804702f349a53e1.pdf
Vector-valued multilinear operator
singular integral operator
sharp maximal function estimate
BMO
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
249
267
363
Symmetric curvature tensor
A. Heydari
1
N. Boroojerdian
2
E. Peyghan
3
Recently, we have used the symmetric bracket of vector fields,
and developed the notion of the symmetric derivation. Using this
machinery, we have defined the concept of symmetric curvature.
This concept is natural and is related to the notions divergence
and Laplacian of vector fields. This concept is also related to
the derivations on the algebra of symmetric forms which has been
discussed by the authors. We introduce a new class of geometric
vector fields and prove some basic facts about them. We call
these vector fields affinewise. By contraction of the symmetric
curvature, we define two new curvatures which have direct
relations to the notions of divergence, Laplacian, and the Ricci
tensor.
http://bims.iranjournals.ir/article_363_e4d5cfe09b33d8f0691b0f0663d7edef.pdf
Curvature tensor
derivation
Fr"{o}licher-Nijenhuis bracket
Lie derivative
symmetric
differential
symmetric curvature
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
269
279
364
The (R,S)-symmetric and (R,S)-skew symmetric solutions of the pair of matrix equations A1XB1 = C1 and A2XB2 = C2
M. Dehghan
1
M. Hajarian
2
Let $Rin textbf{C}^{mtimes m}$ and $Sin textbf{C}^{ntimes n}$ be nontrivial involution matrices; i.e., $R=R^{-1}neq pm~I$ and $S=S^{-1}neq pm~I$.
An $mtimes n$ complex matrix $A$ is said to be an $(R, S)$-symmetric ($(R, S)$-skew symmetric) matrix if $RAS =A$ ($ RAS =-A$).
The $(R, S)$-symmetric and $(R, S)$-skew symmetric matrices have
a number of special properties and widely used in engineering and
scientific computating. Here, we introduce the necessary and
sufficient conditions for the solvability of the pair of matrix
equations $A_{1}XB_{1}=C_{1}$ and $A_{2}XB_{2}=C_{2}$, over $(R,
S)$-symmetric and $(R, S)$-skew symmetric matrices, and give the
general expressions of the solutions for the solvable cases.
Finally, we give necessary and sufficient conditions for the
existence of $(R, S)$-symmetric and $(R, S)$-skew symmetric
solutions and representations of these solutions to the pair of
matrix equations in some special cases.
http://bims.iranjournals.ir/article_364_7532efcddc42e213d1eae59596ad5a4a.pdf
Matrix equation
(R
S)-symmetric matrix
S)-skew symmetric matrix
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-09-15
37
No. 3
281
289
365
On the nilpotency class of the automorphism group of some finite
p-groups
S. Fouladi
1
R. Orfi
2
Let $G$ be a $p$-group of order $p^n$ and $Phi$=$Phi(G)$ be the
Frattini subgroup of $G$. It is shown that the nilpotency class of
$Autf(G)$, the group of all automorphisms of $G$ centralizing $G/
Fr(G)$, takes the maximum value $n-2$ if and only if $G$ is of
maximal class. We also determine the nilpotency class of
$Autf(G)$ when $G$ is a finite abelian $p$-group.
http://bims.iranjournals.ir/article_365_cf69e5755ef787ecc4678fb8887eef0b.pdf
Finite p-group
automorphism group
nilpotency class
eng
Iranian Mathematical Society (IMS)
Bulletin of the Iranian Mathematical Society
1017-060X
1735-8515
2011-03-15
37
No. 3
291
304
366
Linear Sphericity Testing of 3-Connected Single Source Digraphs
A. Dolati
1
It has been proved that sphericity testing for digraphs is an
NP-complete problem. Here, we
investigate sphericity of 3-connected single source digraphs. We
provide a new combinatorial characterization of sphericity and give
a linear time algorithm for sphericity testing. Our algorithm tests
whether a 3-connected single source digraph with $n$ vertices is
spherical in $O(n)$ time.
http://bims.iranjournals.ir/article_366_32f7b095391488c7c2d848a209f52492.pdf
Embedding
upward embedding
sphericity
single
source digraph