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Kyungpook mathematical journal
Journal Basic Information
pISSN :
1225-6951
eISSN :
0454-8124
Journal DOI :
10.5666/KMJ
Frequency :
Others
Publisher:
Department of Mathematics, Kyungpook National University
Editor in Chief :
Sang-Dong Kim
Volume & Issues
Volume 49, Issue 4 - Dec 2009
Volume 49, Issue 3 - Sep 2009
Volume 49, Issue 2 - Jun 2009
Volume 49, Issue 1 - Mar 2009
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1
On Self-commutator Approximants
Duggal, Bhagwati Prashad ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 1~6
DOI : 10.5666/KMJ.2009.49.1.001
Abstract
Let B(X) denote the algebra of operators on a complex Banach space X, H(X) = {h
B(X) : h is hermitian}, and J(X) = {x
B(X) : x =
+
,
and
H(X)}. Let
B(B(X)) denote the derivation
= ax - xa. If J(X) is an algebra and
for some
, then
for all
. The cases J(X) = B(H), the algebra of operators on a complex Hilbert space, and J(X) =
, the von Neumann-Schatten p-class, are considered.
2
Representations of the Braid Group and Punctured Torus Bundles
Morifuji, Takayuki ; Suzuki, Masaaki ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 7~14
DOI : 10.5666/KMJ.2009.49.1.007
Abstract
In this short note, we consider a family of linear representations of the braid group and the fundamental group of a punctured torus bundle over the circle. We construct an irreducible (special) unitary representation of the fundamental group of a closed 3-manifold obtained by the Dehn filling.
3
Uniqueness of Meromorphic Functions That Share Three Sets
Banerjee, Abhijit ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 15~29
DOI : 10.5666/KMJ.2009.49.1.015
Abstract
Dealing with a question of gross, we prove some uniqueness theorems concerning meromorphic functions with the notion of weighted sharing of sets. Our results will not only improve and supplement respectively two results of Lahiri-Banerjee [9] and Qiu and Fang [13] but also improve a very recent result of the present author [1].
4
Fractional Integrals and Generalized Olsen Inequalities
Gunawan, Hendra ; Eridani, Eridani ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 31~39
DOI : 10.5666/KMJ.2009.49.1.031
Abstract
Let
be the generalized fractional integral operator associated to a function
, as defined in [16]. For a function W on
, we shall be interested in the boundedness of the multiplication operator
on generalized Morrey spaces. Under some assumptions on
, we obtain an inequality for
, which can be viewed as an extension of Olsen's and Kurata-Nishigaki-Sugano's results.
5
Ideals of the Multiplicative Semigroups ℤ
_{n}
and their Products
Puninagool, Wattapong ; Sanwong, Jintana ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 41~46
DOI : 10.5666/KMJ.2009.49.1.041
Abstract
The multiplicative semigroups
have been widely studied. But, the ideals of
seem to be unknown. In this paper, we provide a complete descriptions of ideals of the semigroups
and their product semigroups
. We also study the numbers of ideals in such semigroups.
6
On Sufficient Conditions for Certain Subclass of Analytic Functions Defined by Convolution
Sooriyakala, Paramasivam ; Marikkannan, Natarajan ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 47~55
DOI : 10.5666/KMJ.2009.49.1.047
Abstract
In the present investigation sufficient conditions are found for certain subclass of normalized analytic functions defined by Hadamard product. Differential sandwich theorems are also obtained. As a special case of this we obtain results involving Ruscheweyh derivative, S
l
gean derivative, Carlson-shaffer operator, Dziok-Srivatsava linear operator, Multiplier transformation.
7
On Approximation by Post-Widder and Stancu Operators Preserving x
^{2}
Rempulska, Lucyna ; Skorupka, Mariola ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 57~65
DOI : 10.5666/KMJ.2009.49.1.057
Abstract
In the papers [5]-[7] was examined approximation of functions by the modified Sz
sz-Mrakyan operators and other positive linear operators preserving
. In this paper we introduce the Post-Widder and Stancu operators preserving
in polynomial weighted spaces. We show that these operators have better approximation properties than classical Post-Widder and Stancu operators.
8
On the Generalized Hyers-Ulam-Rassias Stability of Higher Ring Derivations
Park, Kyoo-Hong ; Jung, Yong-Soo ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 67~79
DOI : 10.5666/KMJ.2009.49.1.067
Abstract
We establish the generalized Hyers-Ulam-Rassias stability of higher ring derivations. Furthermore, we use the superstability of higher ring derivations to obtain approximately higher linear derivations mapping into the Jacobson radical under some conditions.
9
Application of Bifurcation Method to a Generalized Modified Boussinesq Equation
Song, Ming ; Yang, Chengxi ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 81~93
DOI : 10.5666/KMJ.2009.49.1.081
Abstract
Bifurcation method of dynamical systems is employed to investigate exact solitary wave solutions and kink wave solutions in the generalized modified Boussinesq equation. Under some parameter conditions, their explicit expressions are obtained. Some previous results are extended.
10
A Class of Starlike Functions Defined by the Dziok-Srivastava Operator
Silverman, Herb ; Murugusundaramoorhty, Gangadharan ; Vijaya, Kaliappan ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 95~106
DOI : 10.5666/KMJ.2009.49.1.095
Abstract
A comprehensive class of starlike univalent functions defined by Dziok-Srivastava operator is introduced. Necessary and sufficient coefficient bounds are given for functions in this class to be starlike. Further distortion bounds, extreme points and results on partial sums are investigated.
11
Small Functions of Meromorphic Functions that Share Three Values GCM
Alzahary, Thamir Chilaap ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 107~122
DOI : 10.5666/KMJ.2009.49.1.107
Abstract
In this paper, we deal with the problem of uniqueness of meromorphic functions that share three values, and obtain some theorems which improve some results of Brosch, Yi and other authors.
12
The Signless Laplacian Spectral Radius of Unicyclic Graphs with Graph Constraints
Feng, Lihua ; Yu, Guihai ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 123~131
DOI : 10.5666/KMJ.2009.49.1.123
Abstract
In this paper, we study the signless Laplacian spectral radius of unicyclic graphs with prescribed number of pendant vertices or independence number. We also characterize the extremal graphs completely.
13
On Semiparallel and Weyl-semiparallel Hypersurfaces of Kaehler Manifolds
Ozgur, Cihan ; Murathan, Cengizhan ; Arslan, Kadri ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 133~141
DOI : 10.5666/KMJ.2009.49.1.133
Abstract
We study on semiparallel and Weyl semiparallel Sasakian hypersurfaces of Kaehler manifolds. We prove that a (2n + 1)-dimensional Sasakian hypersurface M of a (2n+2)-dimensional Kaehler manifold
is semiparallel if and only if it is totally umbilical with unit mean curvature, if dimM = 3 and
is a Calabi-Yau manifold, then
is flat at each point of M. We also prove that such a hypersurface M is Weyl-semiparallel if and only if it is either an
-Einstein manifold or semiparallel. We also investigate the extended classes of semiparallel and Weyl semiparallel Sasakian hypersurfaces of Kaehler manifolds.
14
Meromorphic Functions Sharing a Small Function with Their Derivatives
Zhang, Jilong ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 143~154
DOI : 10.5666/KMJ.2009.49.1.143
Abstract
In this paper, we investigate uniqueness problems of meromorphic functions that share a small function with one of their derivatives, and give some results to improve some previous results.
15
Integral Transforms of Square Integrable Functionals on Yeh-Wiener Space
Kim, Byoung-Soo ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 155~166
DOI : 10.5666/KMJ.2009.49.1.155
Abstract
We give a necessary and sufficient condition that a square integrable functional F(x) on Yeh-Wiener space has an integral transform
which is also square integrable. This extends the result by Kim and Skoug for functional F(x) in
.
16
Geometric Means of Positive Operators
Nakamura, Noboru ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 167~181
DOI : 10.5666/KMJ.2009.49.1.167
Abstract
Based on Ricatti equation
for two (positive invertible) operators A and B which has the geometric mean
as its solution, we consider a cubic equation
for A, B and C. The solution X =
is a candidate of the geometric mean of the three operators. However, this solution is not invariant under permutation unlike the geometric mean of two operators. To supply the lack of the property, we adopt a limiting process due to Ando-Li-Mathias. We define reasonable geometric means of k operators for all integers
by induction. For three positive operators, in particular, we define the weighted geometric mean as an extension of that of two operators.
17
Pseudo-Rank Functions on Rickart *-rings
Nimbhorkar, Shriram Khanderao ;
Kyungpook mathematical journal, volume 49, issue 1, 2009, Pages 183~193
DOI : 10.5666/KMJ.2009.49.1.183
Abstract
Pseudo-rank functions on Rickart *-rings are introduced and their properties are studied.