# Journal of theKorean Mathematical SocietyJKMS

ISSN(Print) 0304-9914 ISSN(Online) 2234-3008

• ### 2021-05-01

#### A finite difference/finite volume method for solving the fractional diffusion wave equation

Yinan Sun, Tie Zhang

• ### 2020-11-01

#### Erd\H os-Ko-Rado type theorems for simplicial complexes via algebraic shifting

Younjin Kim

Abstract : In 2009, Borg~\cite{BORG13} suggested a conjecture concerning the size of a $t$-intersecting $k$-uniform family of faces of an arbitrary simplicial complex. In this paper, we give a strengthening of Borg's conjecture for shifted simplicial complexes using algebraic shifting.

• ### 2020-07-01

#### On the $C$-projective vector fields on Randers spaces

Abstract : A characterization of the $C$-projective vector fields on a Randers space is presented in terms of ${\bf\Xi}$-curvature. It is proved that the ${\bf\Xi}$-curvature is invariant for $C$-projective vector fields. The dimension of the algebra of the $C$-projective vector fields on an $n$-dimensional Randers space is at most $n(n+2)$. The generalized Funk metrics on the $n$-dimensional Euclidean unit ball $\mathbb{B}^n(1)$ are shown to be explicit examples of the Randers metrics with a $C$-projective algebra of maximum dimension $n(n+2)$. Then, it is also proved that an $n$-dimensional Randers space has a $C$-projective algebra of maximum dimension $n(n+2)$ if and only if it is locally Minkowskian or (up to re-scaling) locally isometric to the generalized Funk metric. A new projective invariant is also introduced.

• ### 2021-11-01

#### Symmetric and pseudo-symmetric numerical semigroups via Young diagrams and their semigroup rings

Meral Suer, Mehmet Yesil

Abstract : This paper studies Young diagrams of symmetric and pseudo-symmetric numerical semigroups and describes new operations on Young diagrams as well as numerical semigroups. These provide new decompositions of symmetric and pseudo-symmetric semigroups into a numerical semigroup and its dual. It is also given exactly for what kind of numerical semigroup $S$, the semigroup ring ${\mathbb k}[\![S]\!]$ has at least one Gorenstein subring and has at least one Kunz subring.

• ### 2021-07-01

#### Prime knots with arc index 12 up to 16 crossings

Gyo Taek Jin, Hyuntae Kim, Seungwoo Lee, Hun Joo Myung

Abstract : We obtain the list of prime knots with arc index 12 up to 16 crossings and their minimal grid diagrams. This is a continuation of the works \cite{Jin2006} and \cite{Jin2011} in which Cromwell matrices were generated to obtain minimal grid diagrams of all prime knots up to arc index 11. We provide minimal grid diagrams of the prime alternating knots with arc index 12. They are the 10 crossing prime alternating knots. The full list of 19,513 prime knots of arc index 12 up to 16 crossings and their minimal grid diagrams can be found in the arXiv~\cite{Jin2020}.

• ### 2021-03-01

#### Monoidal functors and exact sequences of groups for Hopf quasigroups

Jos\'{e} N. Alonso \'{A}lvarez, Jos\'{e} M. Fern\'{a}ndez Vilaboa, Ram\'{o}n Gonz\'{a}lez Rodr\'{\i}guez

Abstract : In this paper we introduce the notion of strong Galois $H$-progenerator object for a finite cocommutative Hopf quasigroup $H$ in a symmetric monoidal category ${\sf C}$. We prove that the set of isomorphism classes of strong Galois $H$-progenerator objects is a subgroup of the group of strong Galois $H$-objects introduced in \cite{JKMS}. Moreover, we show that strong Galois $H$-progenerator objects are preserved by strong symmetric monoidal functors and, as a consequence, we obtain an exact sequence involving the associated Galois groups. Finally, to the previous functors, if $H$ is finite, we find exact sequences of Picard groups related with invertible left $H$-(quasi)modules and an isomorphism $Pic(_{{\sf H}}{\sf Mod})\cong Pic({\sf C})\oplus G(H^{\ast})$ where $Pic(_{{\sf H}}{\sf Mod})$ is the Picard group of the category of left $H$-modules, $Pic({\sf C})$ the Picard group of ${\sf C}$, and $G(H^{\ast})$ the group of group-like morphisms of the dual of $H$.

## Current Issue

• ### Some numerical radius inequalities for semi-Hilbert space operators

Kais Feki

J. Korean Math. Soc. 2021; 58(6): 1385-1405
https://doi.org/10.4134/JKMS.j210017

• ### Inclusion relations and radius problems for a subclass of starlike functions

Prachi Gupta, Sumit Nagpal, Vaithiyanathan Ravichandran

J. Korean Math. Soc. 2021; 58(5): 1147-1180
https://doi.org/10.4134/JKMS.j200465

• ### Erratum to Static and related critical spaces with harmonic curvature and three Ricci eigenvalues'' [J. Korean Math. Soc. 57 (2020), No. 6, pp. 1435--1449]

Jongsu Kim

J. Korean Math. Soc. 2022; 59(3): 649-650
https://doi.org/10.4134/JKMS.j210761

• ### Existence of global solutions to some nonlinear equations on locally finite graphs

Yanxun Chang, Xiaoxiao Zhang

J. Korean Math. Soc. 2021; 58(3): 703-722
https://doi.org/10.4134/JKMS.j200221

• ### Birkhoff's ergodic theorems in terms of weighted inductive means

Byoung Jin Choi, Jae Hun Kim

J. Korean Math. Soc. 2022; 59(3): 549-570
https://doi.org/10.4134/JKMS.j210239

• ### Stabilized-penalized collocated finite volume scheme for incompressible biofluid flows

Nasserdine Kechkar, Mohammed Louaar

J. Korean Math. Soc. 2022; 59(3): 519-548
https://doi.org/10.4134/JKMS.j210211

• ### Preservation of expansivity in hyperspace dynamical systems

Namjip Koo, Hyunhee Lee

J. Korean Math. Soc. 2021; 58(6): 1421-1431
https://doi.org/10.4134/JKMS.j210052

• ### Every abelian group is the class group of a ring of Krull type

Gyu Whan Chang

J. Korean Math. Soc. 2021; 58(1): 149-171
https://doi.org/10.4134/JKMS.j200010