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Journal of the Korean Mathematical Society
Journal Basic Information
pISSN :
0304-9914
eISSN :
2234-3008
Journal DOI :
10.4134/JKMS
Frequency :
Others
Publisher:
The Korean Mathematical Society
Editor in Chief :
Volume & Issues
Volume 47, Issue 6 - Nov 2010
Volume 47, Issue 5 - Sep 2010
Volume 47, Issue 4 - Jul 2010
Volume 47, Issue 3 - May 2010
Volume 47, Issue 2 - Mar 2010
Volume 47, Issue 1 - Jan 2010
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1
OSCILLATORY BEHAVIOR OF A CERTAIN CLASS OF SECOND-ORDER NONLINEAR PERTURBED DYNAMIC EQUATIONS ON TIME SCALES
Saker, Samir H. ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 659~674
DOI : 10.4134/JKMS.2010.47.4.659
Abstract
This paper is concerned with the asymptotic behavior of solutions of the second-order nonlinear perturbed dynamic equation
on a time scale
. By using a new technique we establish some sufficient conditions which ensure that every solution oscillates or converges to zero. Our results improve the known oscillation results on the literature for the perturbed dynamic equations on time scales. Some examples illustrating our main results are given.
2
ON THE TOPOLOGY OF DIFFEOMORPHISMS OF SYMPLECTIC 4-MANIFOLDS
Kim, Jin-Hong ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 675~689
DOI : 10.4134/JKMS.2010.47.4.675
Abstract
For a closed symplectic 4-manifold X, let
(X) be the group of diffeomorphisms of X smoothly isotopic to the identity, and let Symp(X) be the subgroup of
(X) consisting of symplectic automorphisms. In this paper we show that for any finitely given collection of positive integers {
,
,
,
} and any non-negative integer m, there exists a closed symplectic (or K
hler) 4-manifold X with
(X) > m such that the homologies
of the quotient space
(X)/Symp(X) over the rational coefficients are non-trivial for all odd degrees i =
- 1,
,
- 1. The basic idea of this paper is to use the local invariants for symplectic 4-manifolds with contact boundary, which are extended from the invariants of Kronheimer for closed symplectic 4-manifolds, as well as the symplectic compactifications of Stein surfaces of Lisca and Mati
.
3
GORENSTEIN-INJECTORS, GORENSTEIN-FLATORS
Gu, Qinqin ; Zhu, Xiaosheng ; Zhou, Wenping ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 691~704
DOI : 10.4134/JKMS.2010.47.4.691
Abstract
Over a ring R, let
be a finitely generated projective right R-module. Then we define the G-injector (G-projector) if
preservers Gorenstein injective modules (Gorenstein projective modules), the Gflator if
preservers Gorenstein flat modules. G-injector (G-flator) and G-injector are characterized focus primarily on the cases where R is a Gorenstein ring, and under this condition we also study the relations between the injector (projector, flator) and the G-injector (G-projector, G-flator). Over any ring we also give the characteristics of G-injector (G-flator) by the Gorenstein injective (Gorenstein flat) dimensions of modules.
4
LIE BIALGEBRAS ARISING FROM POISSON BIALGEBRAS
Oh, Sei-Qwon ; Cho, Eun-Hee ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 705~718
DOI : 10.4134/JKMS.2010.47.4.705
Abstract
It gives a method to obtain a natural Lie bialgebra from a Poisson bialgebra by an algebraic point of view. Let g be a coboundary Lie bialgebra associated to a Poission Lie group G. As an application, we obtain a Lie bialgebra from a sub-Poisson bialgebra of the restricted dual of the universal enveloping algebra U(g).
5
A STRUCTURE ON COEFFICIENTS OF NILPOTENT POLYNOMIALS
Jeon, Young-Cheol ; Lee, Yang ; Ryu, Sung-Ju ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 719~733
DOI : 10.4134/JKMS.2010.47.4.719
Abstract
We observe a structure on the products of coefficients of nilpotent polynomials, introducing the concept of n-semi-Armendariz that is a generalization of Armendariz rings. We first obtain a classification of reduced rings, proving that a ring R is reduced if and only if the n by n upper triangular matrix ring over R is n-semi-Armendariz. It is shown that n-semi-Armendariz rings need not be (n+1)-semi-Armendariz and vice versa. We prove that a ring R is n-semi-Armendariz if and only if so is the polynomial ring over R. We next study interesting properties and useful examples of n-semi-Armendariz rings, constructing various kinds of counterexamples in the process.
6
ON GENERALIZED λ
_{δ}
^{s}
-SETS AND RELATED TOPICS OPOLOGY
Caldas, Miguel ; Hatir, Esref ; Jafari, Saeid ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 735~742
DOI : 10.4134/JKMS.2010.47.4.735
Abstract
In this paper, we define and study the concept of
-closure operator and the associated topology
on a topological space (X,
) in terms of g.
-sets.
7
BOUNDARY VALUE PROBLEMS FOR THE STATIONARY NORDSTRÖM-VLASOV SYSTEM
Bostan, Mihai ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 743~766
DOI : 10.4134/JKMS.2010.47.4.743
Abstract
We study the existence of weak solution for the stationary Nordstr
m-Vlasov equations in a bounded domain. The proof follows by fixed point method. The asymptotic behavior for large light speed is analyzed as well. We justify the convergence towards the stationary Vlasov-Poisson model for stellar dynamics.
8
MODIFIED LIMITED MEMORY BFGS METHOD WITH NONMONOTONE LINE SEARCH FOR UNCONSTRAINED OPTIMIZATION
Yuan, Gonglin ; Wei, Zengxin ; Wu, Yanlin ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 767~788
DOI : 10.4134/JKMS.2010.47.4.767
Abstract
In this paper, we propose two limited memory BFGS algorithms with a nonmonotone line search technique for unconstrained optimization problems. The global convergence of the given methods will be established under suitable conditions. Numerical results show that the presented algorithms are more competitive than the normal BFGS method.
9
A VERY SINGULAR SOLUTION OF A DOUBLY DEGENERATE PARABOLIC EQUATION WITH NONLINEAR CONVECTION
Fang, Zhong Bo ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 789~804
DOI : 10.4134/JKMS.2010.47.4.789
Abstract
We here investigate an existence and uniqueness of the nontrivial, nonnegative solution of a nonlinear ordinary differential equation:
satisfying a specific decay rate:
= 0 with
:= (p - 1)/[pd-(m+1)(p-1)] and
:= [q-m(p-1)]/[pd-(m+1)(p-1)]. Here m(p-1) > 1 and m(p - 1) < q < (m+1)(p-1). Such a solution arises naturally when we study a very singular solution for a doubly degenerate equation with nonlinear convection:
defined on the half line.
10
NONBIJECTIVE IDEMPOTENTS PRESERVERS OVER SEMIRINGS
Orel, Marko ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 805~818
DOI : 10.4134/JKMS.2010.47.4.805
Abstract
We classify linear maps which preserve idempotents on
matrices over some classes of semirings. Our results include many known semirings like the semiring of all nonnegative integers, the semiring of all nonnegative reals, any unital commutative ring, which is zero divisor free and of characteristic not two (not necessarily a principal ideal domain), and the ring of integers modulo m, where m is a product of distinct odd primes.
11
PIERCE STALKS OF EXCHANGE RINGS
Chen, Huanyin ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 819~830
DOI : 10.4134/JKMS.2010.47.4.819
Abstract
We prove, in this article, that a ring R is a stable exchange ring if and only if so are all its Pierce stalks. If every Pierce stalks of R is artinian, then
= u +
with u,
U(R) if and only if for any a
R, there exist u,
U(R) such that a = u +
. Furthermore, there exists u
U(R) such that
if and only if for any a
R, there exists u
U(R) such that
. We will give analogues to normal exchange rings. The root properties of such exchange rings are also obtained.
12
PERTURBATION ANALYSIS OF THE MOORE-PENROSE INVERSE FOR A CLASS OF BOUNDED OPERATORS IN HILBERT SPACES
Deng, Chunyuan ; Wei, Yimin ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 831~843
DOI : 10.4134/JKMS.2010.47.4.831
Abstract
Let
and
be Hilbert spaces and let T,
= T +
be bounded operators from
into
. In this article, two facts related to the perturbation bounds are studied. The first one is to find the upper bound of
which extends the results obtained by the second author and enriches the perturbation theory for the Moore-Penrose inverse. The other one is to develop explicit representations of projectors
and
. In addition, some spectral cases related to these results are analyzed.
13
THE NEHARI MANIFOLD APPROACH FOR DIRICHLET PROBLEM INVOLVING THE p(x)-LAPLACIAN EQUATION
Mashiyev, Rabil A. ; Ogras, Sezai ; Yucedag, Zehra ; Avci, Mustafa ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 845~860
DOI : 10.4134/JKMS.2010.47.4.845
Abstract
In this paper, using the Nehari manifold approach and some variational techniques, we discuss the multiplicity of positive solutions for the p(x)-Laplacian problems with non-negative weight functions and prove that an elliptic equation has at least two positive solutions.
14
EXPANSIONS OF REAL NUMBERS IN NON-INTEGER BASES
Chunarom, Danita ; Laohakosol, Vichian ;
Journal of the Korean Mathematical Society, volume 47, issue 4, 2010, Pages 861~877
DOI : 10.4134/JKMS.2010.47.4.861
Abstract
The works of Erd
s et al. about expansions of 1 with respect to a non-integer base q, referred to as q-expansions, are investigated to determine how far they continue to hold when the number 1 is replaced by a positive number x. It is found that most results about q-expansions for real numbers greater than or equal to 1 are in somewhat opposite direction to those for real numbers less than or equal to 1. The situation when a real number has a unique q-expansion, and when it has exactly two q-expansions are studied. The smallest base number q yielding a unique q-expansion is determined and a particular sequence is shown, in certain sense, to be the smallest sequence whose corresponding base number q yields exactly two q-expansions.