권호 표지

Journal of the Korean Mathematical Society (대한수학회지)

Korean Mathematical Society

  • Bimonthly
  • /
  • 0304-9914(pISSN)
  • /
  • 2234-3008(eISSN)

Aim & Scope

This journal endeavors to publish significant research of broad interests in pure and applied mathematics. One volume is published each year, and each volume consists of six issues (January, March, May, July, September, November).

http://jkms.kms.or.kr/submission KSCI KCI SCOPUS SCI SCIE

Volume 47 Issue 4

  1. Saker, Samir H. 659
    https://doi.org/10.4134/JKMS.2010.47.4.659 PDF KSCI
    This paper is concerned with the asymptotic behavior of solutions of the second-order nonlinear perturbed dynamic equation $$(r(t)x^{\Delta}(t))^{\Delta}\;+\;F(t,\;x^{\sigma}))=G(t,\;x^{\sigma},\;(x^{\Delta})^{\sigma})$$ on a time scale $\mathbb{T}$. 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. Kim, Jin-Hong 675
    https://doi.org/10.4134/JKMS.2010.47.4.675 PDF KSCI
    For a closed symplectic 4-manifold X, let $Diff_0$(X) be the group of diffeomorphisms of X smoothly isotopic to the identity, and let Symp(X) be the subgroup of $Diff_0$(X) consisting of symplectic automorphisms. In this paper we show that for any finitely given collection of positive integers {$n_1$, $n_2$, $\ldots$, $n_k$} and any non-negative integer m, there exists a closed symplectic (or K$\ddot{a}$hler) 4-manifold X with $b_2^+$ (X) > m such that the homologies $H_i$ of the quotient space $Diff_0$(X)/Symp(X) over the rational coefficients are non-trivial for all odd degrees i = $2n_1$ - 1, $\ldots$, $2n_k$ - 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$\acute{c}$.
  3. Gu, Qinqin;Zhu, Xiaosheng;Zhou, Wenping 691
    https://doi.org/10.4134/JKMS.2010.47.4.691 PDF KSCI
    Over a ring R, let $P_R$ be a finitely generated projective right R-module. Then we define the G-injector (G-projector) if $P_R$ preservers Gorenstein injective modules (Gorenstein projective modules), the Gflator if $P_R$ 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. Oh, Sei-Qwon;Cho, Eun-Hee 705
    https://doi.org/10.4134/JKMS.2010.47.4.705 PDF KSCI
    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. Jeon, Young-Cheol;Lee, Yang;Ryu, Sung-Ju 719
    https://doi.org/10.4134/JKMS.2010.47.4.719 PDF KSCI
    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. Caldas, Miguel;Hatir, Esref;Jafari, Saeid 735
    https://doi.org/10.4134/JKMS.2010.47.4.735 PDF KSCI
    In this paper, we define and study the concept of $\wedge^s_{\delta}$-closure operator and the associated topology $\tau^{\wedge}^s_{\delta}$ on a topological space (X, $\tau$) in terms of g.$\wedge^s_{\delta}$-sets.
  7. Bostan, Mihai 743
    https://doi.org/10.4134/JKMS.2010.47.4.743 PDF KSCI
    We study the existence of weak solution for the stationary Nordstr$\ddot{o}$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. Yuan, Gonglin;Wei, Zengxin;Wu, Yanlin 767
    https://doi.org/10.4134/JKMS.2010.47.4.767 PDF KSCI
    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. Fang, Zhong Bo 789
    https://doi.org/10.4134/JKMS.2010.47.4.789 PDF KSCI
    We here investigate an existence and uniqueness of the nontrivial, nonnegative solution of a nonlinear ordinary differential equation: $$[\mid(w^m)]'\mid^{p-2}(w^m)']'\;+\;{\beta}rw'\;+\;{\alpha}w\;+\;(w^q)'\;=\;0$$ satisfying a specific decay rate: $lim_{r\rightarrow\infty}\;r^{\alpha/\beta}w(r)$ = 0 with $\alpha$ := (p - 1)/[pd-(m+1)(p-1)] and $\beta$:= [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: $$u_t\;=\;[\mid(u^m)_x\mid^{p-2}(u^m)_x]_x\;+\;(u^q)x$$ defined on the half line.
  10. Orel, Marko 805
    https://doi.org/10.4134/JKMS.2010.47.4.805 PDF KSCI
    We classify linear maps which preserve idempotents on $n{\times}n$ 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. Chen, Huanyin 819
    https://doi.org/10.4134/JKMS.2010.47.4.819 PDF KSCI
    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 $1_R$ = u + $\upsilon$ with u, $\upsilon$ $\in$ U(R) if and only if for any a $\in$ R, there exist u, $\upsilon$ $\in$ U(R) such that a = u + $\upsilon$. Furthermore, there exists u $\in$ U(R) such that $1_R\;{\pm}\;u\;\in\;U(R)$ if and only if for any a $\in$ R, there exists u $\in$ U(R) such that $a\;{\pm}\;u\;\in\;U(R)$. We will give analogues to normal exchange rings. The root properties of such exchange rings are also obtained.
  12. Deng, Chunyuan;Wei, Yimin 831
    https://doi.org/10.4134/JKMS.2010.47.4.831 PDF KSCI
    Let $\cal{H}$ and $\cal{K}$ be Hilbert spaces and let T, $\tilde{T}$ = T + ${\delta}T$ be bounded operators from $\cal{H}$ into $\cal{K}$. In this article, two facts related to the perturbation bounds are studied. The first one is to find the upper bound of $\parallel\tilde{T}^+\;-\;T^+\parallel$ 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 $\parallel\tilde{T}\tilde{T}^+\;-\;TT^+\parallel$ and $\parallel\tilde{T}^+\tilde{T}\;-\;T^+T\parallel$. In addition, some spectral cases related to these results are analyzed.
  13. Mashiyev, Rabil A.;Ogras, Sezai;Yucedag, Zehra;Avci, Mustafa 845
    https://doi.org/10.4134/JKMS.2010.47.4.845 PDF KSCI
    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. Chunarom, Danita;Laohakosol, Vichian 861
    https://doi.org/10.4134/JKMS.2010.47.4.861 PDF KSCI
    The works of Erd$\ddot{o}$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.