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Bulletin of the Korean Mathematical Society
Journal Basic Information
pISSN :
1015-8634
eISSN :
2234-3016
Journal DOI :
10.4134/BKMS
Frequency :
Others
Publisher:
The Korean Mathematical Society
Editor in Chief :
Yongnam Lee
Volume & Issues
Volume 41, Issue 4 - Nov 2004
Volume 41, Issue 3 - Aug 2004
Volume 41, Issue 2 - May 2004
Volume 41, Issue 1 - Feb 2004
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1
HYPERCYCLIC OPERATOR WEIGHTED SHIFTS
Hazarika, Munmun ; Arora, S.C. ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 589~598
DOI : 10.4134/BKMS.2004.41.4.589
Abstract
We consider bilateral operator weighted shift T on
(K) with weight sequence
of positive invertible diagonal operators on K. We give a characterization for T to be hypercyclic, and show that the conditions are far simplified in case T is invertible.
2
A GENERALIZATION OF THE JACOBSON RADICAL
Naghipour, A.R. ; Yamini, A.H. ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 599~608
DOI : 10.4134/BKMS.2004.41.4.599
Abstract
Let R be an associative ring with identity and J(R) be the Jacobson radical of R. In this paper we investigate the generalization of the Jacobson radical of R, J＊ (R) say. Also we study the rings that J＊(R) = J(R).
3
PSEUDO-PARALLEL REAL HYPERSURFACES IN COMPLEX SPACE FORMS
Lobos, Guillermo A. ; Ortega, Miguel ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 609~618
DOI : 10.4134/BKMS.2004.41.4.609
Abstract
Pseudo-parallel real hypersurfaces in complex space forms can be defined as an extrinsic analogues of pseudo-symmetric real hypersurfaces, that generalize the notion of semi-symmetric real hypersurface. In this paper a classification of the pseudo-parallel real hypersurfaces in a non-flat complex space forms is obtained.
4
OSCILLATION OF PARABOLIC NEUTRAL DELAY DIFFERENCE EQUATIONS
Saker, S.H. ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 619~632
DOI : 10.4134/BKMS.2004.41.4.619
Abstract
Some new oscillation criteria for parabolic neutral delay difference equations corresponding to two sets of boundary conditions are obtained. Our results improve the well known results in the literature.
5
NEW INEQUALITIES OF OSTROWSKI AND TRAPEZOID TYPE FOR N-TIME DIFFERENTIABLE FUNCTIONS
Pachpatte, B.G. ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 633~639
DOI : 10.4134/BKMS.2004.41.4.633
Abstract
In this paper using integral representations for n-time differentiable mappings, we establish new generalizations of certain Ostrowski and Trapezoid type inequalities by using fairly elementary analysis.
6
ON ZEROS OF CERTAIN SUMS OF POLYNOMIALS
Kim, Seon-Hong ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 641~646
DOI : 10.4134/BKMS.2004.41.4.641
Abstract
A convex combination of two products with same degree of finitely many finite geometric series with each having even degree does not always have all its zeros on the unit circle. However, in this paper, we show that a polynomial obtained by just adding a finite geometric series multiplied by a large constant to such a convex combination has all its zeros on the unit circle.
7
ON SOME TYPES OF CONTINUOUS FUZZY MULTIFUNCTIONS
Ekici, Erdal ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 647~656
DOI : 10.4134/BKMS.2004.41.4.647
Abstract
In this paper, by using operations, some characterizations and some properties of fuzzy lower and upper continuous multifunctions and its weaker and stronger forms including fuzzy lower and upper weakly continuous, fuzzy lower and upper
, fuzzy lower and upper strongly
, fuzzy lower and upper almost strongly
, fuzzy lower and upper weakly
, fuzzy lower and upper almost continuous, fuzzy lower and upper super continuous, fuzzy lower and upper
, are presented.
8
SKEW POWER SERIES EXTENSIONS OF α-RIGID P.P.-RINGS
Hashemi, Ebrahim ; Moussavi, Ahmad ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 657~664
DOI : 10.4134/BKMS.2004.41.4.657
Abstract
We investigate skew power series of
-rigid p.p.-rings, where
is an endomorphism of a ring R which is not assumed to be surjective. For an
-rigid ring R, R[[
]] is right p.p., if and only if R[[
]] is right p.p., if and only if R is right p.p. and any countable family of idempotents in R has a join in I(R).
9
ASYMPTOTIC STABILITY IN GENERAL DYNAMICAL SYSTEMS
Lim, Young-Il ; Lee, Kyung-Bok ; Park, Jong-Soh ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 665~676
DOI : 10.4134/BKMS.2004.41.4.665
Abstract
In this paper we characterize asymptotic stability via Lyapunov function in general dynamical systems on c-first countable space. We give a family of examples which have first countable but not c-first countable, also c-first countable and locally compact space but not metric space. We obtain several necessary and sufficient conditions for a compact subset M of the phase space X to be asymptotic stability.
10
AN EMBEDDING OF BIRGET-RHODES EXPANSION OF GROUPS INTO A SEMIDIRECT PRODUCT
Choi, Keun-Bae ; Lim, Yong-Do ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 677~690
DOI : 10.4134/BKMS.2004.41.4.677
Abstract
In this paper, we prove that the Birget-Rhodes expansion
of a group G is not a semi direct product of a semilattice by a group but it can be nicely embedded into such a semi direct product.
11
THE INDEX FORM ON THE MULTIPLY WARPED SPACETIME
Choi, Jae-Dong ; Kim, Mi-Suk ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 691~697
DOI : 10.4134/BKMS.2004.41.4.691
Abstract
In this paper we find index form of the multiply warped product manifolds to investigate the physical properties from space-time.
12
NONEXISTENCE OF RICCI-PARALLEL REAL HYPERSURFACES IN P
_{2}
C OR H
_{2}
C
Kim, Un-Kyu ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 699~708
DOI : 10.4134/BKMS.2004.41.4.699
Abstract
Niebergall and Ryan posed many open problems on real hypersurfaces in complex space forms. One of them is "Are there any Ricci-parallel real hypersurfaces in complex projective space
or complex hyperbolic space
\ulcorner" The purpose of present paper is to prove the nonexistence of such hypersurfaces.
13
PUNCTURED TORUS REPRESENTATIONS USING THE GLUING METHOD
Kim, Hong-Chan ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 709~721
DOI : 10.4134/BKMS.2004.41.4.709
Abstract
A punctured torus
(1, 1) is a building block of oriented surfaces. In this paper we formulate the matrix presentations of elements of the Teichmuller space of a punctured torus using the matrix presentations of a pair of pants
(0, 3) and the gluing method.
14
SOME RESULTS ON D-ADMISSIBLE (Є, Є Vq)-Fuzzy SUBGROUPS
Kim, Dae-Sig ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 723~730
DOI : 10.4134/BKMS.2004.41.4.723
Abstract
The definition of a D-admissible fuzzy subset for an operator domain D on a group G is modified to obtain new kinds of (
)-fuzzy subgroups such as an (
)-fuzzy normal subgroup, an (<
)-fuzzy characteristic subgroup, an (<
)-fuzzy fully invariant subgroup which are invariant under D. As results, some of the fundamental properties of such (
)-fuzzy subgroups are obtained.ﾖ⨀ᔌ넀㔷〮㔻Ԁ䭃䑎䷗ᜓ5㘰㬅K䍄乍숗ጊ㤀Ѐ㔷㔻Ԁ䭃䑎䴀
15
CONFORMAL CHANGE OF THE TENSOR U
^{v}
_{ωμ}
IN 7-DIMENSIONAL g-UFT
Cho, Chung-Hyun ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 731~737
DOI : 10.4134/BKMS.2004.41.4.731
Abstract
We investigate change of the tensor
induced by the conformal change in 7-dimensional g-unified field theory. These topics will be studied for the second class with the first category in 7-dimensional case.
16
ON GRAM′S DETERMINANT IN n-INNER PRODUCT SPACES
Cho, Y.J. ; Matic, M. ; Pecaric, J. ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 739~777
DOI : 10.4134/BKMS.2004.41.4.739
Abstract
An analogue of the Gram's inequality for n-inner product spaces is given. Further, a number of inequalities involving Gram's determinant are stated and proved in terms of n-inner products.
17
LOCALLY NILPOTENT GROUPS WITH THE MINIMAL CONDITION ON NORMAL SUBGROUPS OF INFINITE INDEX
Paek, Dae-Hyun ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 779~783
DOI : 10.4134/BKMS.2004.41.4.779
Abstract
A group G is said to satisfy the minimal condition on normal subgroups of infinite index if there does not exist an infinite properly descending chain
>
> ... of normal subgroups of infinite index in G. We characterize the structure of locally nilpotent groups satisfying this chain condition.
18
DENSENESS OF TEST FUNCTIONS IN THE SPACE OF EXTENDED FOURIER HYPERFUNCTIONS
Kim, Kwang-Whoi ;
Bulletin of the Korean Mathematical Society, volume 41, issue 4, 2004, Pages 785~803
DOI : 10.4134/BKMS.2004.41.4.785
Abstract
We research properties of analytic functions which are exponentially decreasing or increasing. Also we show that the space of test functions is dense in the space of extended Fourier hyper-functions, and that the Fourier transform of the space of extended Fourier hyperfunctions into itself is an isomorphism and Parseval's inequality holds.