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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 44, Issue 4 - Nov 2007
Volume 44, Issue 3 - Aug 2007
Volume 44, Issue 2 - May 2007
Volume 44, Issue 1 - Feb 2007
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1
AN UPPER BOUND OF THE BASIS NUMBER OF THE SEMI-STRONG PRODUCT OF CYCLES WITH BIPARTITE GRAPHS
Jaradat, Mohammed M.M. ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 385~394
DOI : 10.4134/BKMS.2007.44.3.385
Abstract
An upper bound of the basis number of the semi-strong product of cycles with bipartite graphs is given. Also, an example is presented where the bound is achieved.
2
RICCI CURVATURE OF INTEGRAL SUBMANIFOLDS OF AN S-SPACE FORM
Kim, Jeong-Sik ; Dwivedi, Mohit Kumar ; Tripathi, Mukut Mani ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 395~406
DOI : 10.4134/BKMS.2007.44.3.395
Abstract
Involving the Ricci curvature and the squared mean curvature, we obtain a basic inequality for an integral submanifold of an S-space form. By polarization, we get a basic inequality for Ricci tensor also. Equality cases are also discussed. By giving a very simple proof we show that if an integral submanifold of maximum dimension of an S-space form satisfies the equality case, then it must be minimal. These results are applied to get corresponding results for C-totally real submanifolds of a Sasakian space form and for totally real submanifolds of a complex space form.
3
SOME EXAMPLES OF QUASI-ARMENDARIZ RINGS
Hashemi, Ebrahim ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 407~414
DOI : 10.4134/BKMS.2007.44.3.407
Abstract
In [12], McCoy proved that if R is a commutative ring, then whenever g(x) is a zero-divisor in R[x], there exists a nonzero c
R such that cg(x) = 0. In this paper, first we extend this result to monoid rings. Then for a monoid M, we give some examples of M-quasi-Armendariz rings which are a generalization of quasi-Armendariz rings. Every reduced ring is M-quasi-Armendariz for any unique product monoid M and any strictly totally ordered monoid
. Also
is M-quasi-Armendariz when R is reduced and M-Armendariz.
4
NOTE ABOUT THE ISOCHRONICITY OF HAMILTONIAN SYSTEMS AND THE CURVATURE OF THE ENERGY
Gomez, Blas Herrera ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 415~418
DOI : 10.4134/BKMS.2007.44.3.415
Abstract
In this note we show the relationship between the period of a isochronous center of a planar Hamiltonian system and the Gauss curvature of the surface S = (x, y, H(x, y)) where H is the energy function of the system.
5
ONE-PARAMETER GROUPS OF BOEHMIANS
Nemzer, Dennis ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 419~428
DOI : 10.4134/BKMS.2007.44.3.419
Abstract
The space of periodic Boehmians with
-convergence is a complete topological algebra which is not locally convex. A family of Boehmians
such that
is the identity and
for all real numbers
and
is called a one-parameter group of Boehmians. We show that if
is strongly continuous at zero, then
has an exponential representation. We also obtain some results concerning the infinitesimal generator for
.
6
POSITION VECTORS OF A SPACELIKE W-CURVE IN MINKOWSKI SPACE 𝔼
_{1}
^{3}
Ilarslan, Kazim ; Boyacioglu, Ozgur ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 429~438
DOI : 10.4134/BKMS.2007.44.3.429
Abstract
In this paper, we study the position vectors of a spacelike W-curve (or a helix), i.e., curve with constant curvatures, with spacelike, timelike and null principal normal in the Minkowski 3-space
. We give some characterizations for spacelike W - curves whose image lies on the pseudohyperbolical space
and Lorentzian sphere
by using the positions vectors of the curve.
7
GLOBAL ASYMPTOTIC STABILITY OF A HIGHER ORDER DIFFERENCE EQUATION
Hamza, Alaa E. ; Khalaf-Allah, R. ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 439~445
DOI : 10.4134/BKMS.2007.44.3.439
Abstract
The aim of this work is to investigate the global stability, periodic nature, oscillation and the boundedness of solutions of the difference equation
, n = 0, 1, 2,..., where A, B, C are nonnegative real numbers and
, k are nonnegative in tegers,
.
8
FUZZY n-INNER PRODUCT SPACE
Vijayabalaji, Srinivasan ; Thillaigovindan, Natesan ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 447~459
DOI : 10.4134/BKMS.2007.44.3.447
Abstract
The purpose of this paper is to introduce the notion of fuzzy n-inner product space. Ascending family of quasi
-n-norms corresponding to fuzzy quasi n-norm is introduced and we provide some results on it.
9
THE ZEROS OF CERTAIN FAMILY OF SELF-RECIPROCAL POLYNOMIALS
Kim, Seon-Hong ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 461~473
DOI : 10.4134/BKMS.2007.44.3.461
Abstract
For integral self-reciprocal polynomials P(z) and Q(z) with all zeros lying on the unit circle, does there exist integral self-reciprocal polynomial
depending on r such that for any r,
, all zeros of
lie on the unit circle and
= P(z),
= Q(z)? We study this question by providing examples. An example answers some interesting questions. Another example relates to the study of convex combination of two polynomials. From this example, we deduce the study of the sum of certain two products of finite geometric series.
10
COMPOSITION OPERATORS BETWEEN HARDY AND BLOCH-TYPE SPACES OF THE UPPER HALF-PLANE
Sharma, S.D. ; Sharma, Ajay K. ; Ahmed, Shabir ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 475~482
DOI : 10.4134/BKMS.2007.44.3.475
Abstract
In this paper, we study composition operators
, induced by a fixed analytic self-map of the of the upper half-plane, acting between Hardy and Bloch-type spaces of the upper half-plane.
11
PROJECTIONS OF PSEUDOSPHERE IN THE LORENTZ 3-SPACE
Birman, Graciela S. ; Desideri, Graciela M. ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 483~492
DOI : 10.4134/BKMS.2007.44.3.483
Abstract
In this paper, we study the map projections from pseudo-sphere
onto the non-lightlike surfaces in the 3-dimensional Lorentzian space,
, with curvature zero. We show geometrical means and properties of
,
and
projections defined on
to cylinders
and
, respectively, and orthographic and stereographic projections on
to Lorentzian plane,
.
12
WEAK AND STRONG CONVERGENCE CRITERIA OF MODIFIED NOOR ITERATIONS FOR ASYMPTOTICALLY NONEXPANSIVE MAPPINGS IN THE INTERMEDIATE SENSE
Banerjee, Shrabani ; Choudhury, Binayak Samadder ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 493~506
DOI : 10.4134/BKMS.2007.44.3.493
Abstract
In this paper weak and strong convergence theorems of modified Noor iterations to fixed points for asymptotically nonexpansive mappings in the intermediate sense in Banach spaces are established. In one theorem where we establish strong convergence we assume an additional property of the operator whereas in another theorem where we establish weak convergence assume an additional property of the space.
13
BOUNDED SOLUTIONS FOR THE $SCHRËDINGER OPERATOR ON RIEMANNIAN MANIFOLDS
Kim, Seok-Woo ; Lee, Yong-Hah ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 507~516
DOI : 10.4134/BKMS.2007.44.3.507
Abstract
Let M be a complete Riemannian manifold and L be a
operator on M. We prove that if M has finitely many L-nonparabolic ends, then the space of bounded L-harmonic functions on M has the same dimension as the sum of dimensions of the spaces of bounded L-harmonic functions on the L-nonparabolic end, which vanish at the boundary of the end.
14
HYPONORMAL TOEPLITZ OPERATORS ON THE BERGMAN SPACE. II.
Hwang, In-Sung ; Lee, Jong-Rak ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 517~522
DOI : 10.4134/BKMS.2007.44.3.517
Abstract
In this paper we consider the hyponormality of Toeplitz operators
on the Bergman space
with symbol in the case of function
with polynomials f and g. We present some necessary conditions for the hyponormality of
under certain assumptions about the coefficients of
.
15
APPROXIMATING THE STIELTJES INTEGRAL OF BOUNDED FUNCTIONS AND APPLICATIONS FOR THREE POINT QUADRATURE RULES
Dragomir, Sever Silvestru ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 523~536
DOI : 10.4134/BKMS.2007.44.3.523
Abstract
Sharp error estimates in approximating the Stieltjes integral with bounded integrands and bounded integrators respectively, are given. Applications for three point quadrature rules of n-time differentiable functions are also provided.
16
COMMON FIXED POINT AND INVARIANT APPROXIMATION RESULTS
Abbas, Mujahid ; Kim, Jong-Kyu ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 537~545
DOI : 10.4134/BKMS.2007.44.3.537
Abstract
Necessary conditions for the existence of common fixed points for noncommuting mappings satisfying generalized contractive conditions in the setup of certain metrizable topological vector spaces are obtained. As applications, related results on best approximation are derived. Our results extend, generalize and unify various known results in the literature.
17
TEMPORAL AND SPATIAL DECAY RATES OF NAVIER-STOKES SOLUTIONS IN EXTERIOR DOMAINS
Bae, Hyeong-Ohk ; Jin, Bum-Ja ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 547~567
DOI : 10.4134/BKMS.2007.44.3.547
Abstract
We obtain spatial-temporal decay rates of weak solutions of incompressible flows in exterior domains. When a domain has a boundary, the pressure term yields difficulties since we do not have enough information on the pressure term near the boundary. For our calculations we provide an idea which does not require any pressure information. We also estimated the spatial and temporal asymptotic behavior for strong solutions.
18
ON THE STABILITY OF A PEXIDERIZED MIXED TYPE QUADRATIC FUNCTIONAL EQUATION II
Jun, Kil-Woung ; Lee, Jin-Hee ; Lee, Yang-Hi ;
Bulletin of the Korean Mathematical Society, volume 44, issue 3, 2007, Pages 569~587
DOI : 10.4134/BKMS.2007.44.3.569
Abstract
In this paper, we establish the generalized Hyers-Ulam-Rassias stability of the Pexider type quadratic equation
and its general solution.