• 대한수학회보
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• 제38권3호
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• pp.435-441
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• 2001

We obtain a characterization of linear operators on vector spaces and homomorphisms on algebras applying the stability properties of functional equations.

• 한국수학교육학회지시리즈A:수학교육
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• 제10권1호
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• pp.4-5
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• 1972

이 논문은 modules 사이의 homomorphisms의 exact sequence에서 다음과 같은 것을 밝힌 것임. 1. (equation omitted)이 하나의 exact sequence 이고 P가 임의의 R-module일 때 (equation omitted)은 abelian group의 하나의 exact sequence라는 것. 2. (equation omitted)이 exact sequence 이고 P가 임의의 R-modele이면 (equation omitted)는 abelian group의 하나의 exact sequence라는 것.

• 대한수학회지
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• 제53권4호
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• pp.795-834
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• 2016

The main purpose of this paper is to propose a scheme of a proof of the nonsimpleness of the group $Homeo^{\Omega}$ ($D^2$, ${\partial}D^2$) of area preserving homeomorphisms of the 2-disc $D^2$. We first establish the existence of Alexander isotopy in the category of Hamiltonian homeomorphisms. This reduces the question of extendability of the well-known Calabi homomorphism Cal : $Diff^{\Omega}$ ($D^1$, ${\partial}D^2$)${\rightarrow}{\mathbb{R}}$ to a homomorphism ${\bar{Cal}}$ : Hameo($D^2$, ${\partial}D^2$)${\rightarrow}{\mathbb{R}}$ to that of the vanishing of the basic phase function $f_{\underline{F}}$, a Floer theoretic graph selector constructed in [9], that is associated to the graph of the topological Hamiltonian loop and its normalized Hamiltonian ${\underline{F}}$ on $S^2$ that is obtained via the natural embedding $D^2{\hookrightarrow}S^2$. Here Hameo($D^2$, ${\partial}D^2$) is the group of Hamiltonian homeomorphisms introduced by $M{\ddot{u}}ller$ and the author [18]. We then provide an evidence of this vanishing conjecture by proving the conjecture for the special class of weakly graphical topological Hamiltonian loops on $D^2$ via a study of the associated Hamiton-Jacobi equation.

• 대한수학회지
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• 제51권6호
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• pp.1305-1319
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• 2014

A submodule N of a right R-module M is called coneat if for every simple right R-module S, any homomorphism $N{\rightarrow}S$ can be extended to a homomorphism $M{\rightarrow}S$. M is called coneat-flat if the kernel of any epimorphism $Y{\rightarrow}M{\rightarrow}0$ is coneat in Y. It is proven that (1) coneat submodules of any right R-module are coclosed if and only if R is right K-ring; (2) every right R-module is coneat-flat if and only if R is right V -ring; (3) coneat submodules of right injective modules are exactly the modules which have no maximal submodules if and only if R is right small ring. If R is commutative, then a module M is coneat-flat if and only if $M^+$ is m-injective. Every maximal left ideal of R is finitely generated if and only if every absolutely pure left R-module is m-injective. A commutative ring R is perfect if and only if every coneat-flat module is projective. We also study the rings over which coneat-flat and flat modules coincide.

• East Asian mathematical journal
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• 제23권1호
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• pp.23-36
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• 2007

In this paper we consider the fuzzy ideals of N-group G where N is a nearring. We introduce fuzzy ideal ${\theta}_{\mu}$ of the quotient N-group $G/{\mu}$ with respect to a fuzzy ideal $\mu$ of G. If $\mu$ is a fuzzy ideal of G and $\theta$ a fuzzy ideal of $G/{\mu}$ such that ${\theta}_{\mu}\;{\subseteq}\;{\theta}$ and ${\theta}_{\mu}(0)\;=\;{\theta}(0)$, then corresponding ${\sigma}_{\theta}\;:\;G\;{\rightarrow}\;[0,\;1]$ is defined and proved that it is a fuzzy ideal of G such that ${\mu}\;{\subseteq}\;{\sigma}_{\theta}$ and ${\mu}(0)\;=\;{\sigma}_{\theta}(0)$. We also prove some results on homomorphisms and fuzzy ideals of N-groups. The image and preimage of fuzzy ideal $\mu$ under N-group homomorphism were studied. Finally it is obtained that if $f\;:\;G\;{\rightarrow}\;G^1$ is an epimorphism of N-groups, then there is an order preserving bijection between the fuzzy ideals of $G^1$ and the fuzzy ideals of G that are constant on kerf. Some examples related to these concepts were illustrated.

• 호남수학학술지
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• 제26권1호
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• pp.17-41
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• 2004

In this paper, we obtain the intuitionistic fuzzy subgroups generated by intuitionistic fuzzy sets and some properties preserved by a ring homomorphism. Furthermore, we introduce the concept of intuitionistic fuzzy coset and study some of it's properties.

• 호남수학학술지
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• 제33권4호
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• pp.499-518
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• 2011

We obtain the interval-valued fuzzy subgroups generated by interval-valued fuzzy sets and some properties preserved by a ring homomorphism. Furthermore, we introduce the concepts of interval-valued fuzzy coset and study some of it's properties.

• 대한수학회논문집
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• 제10권3호
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• pp.519-525
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• 1995

By using an exact sequence of extension groups corresponding to an isogeny of a Drinfeld module we investigate which extension classes are coming from Hom(G,C). In the last section of this paper an example was given where the connecting homomorphism can be explictly computed.

• 충청수학회지
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• 제12권1호
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• pp.33-41
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• 1999

In this paper, we introduce a new notion, called an QS-algebra, which is related to the areas of BCI/BCK-algebras and discuss the G-part of QS-algebras.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권8호
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• pp.1472-1491
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• 2011

As used product transactions are currently on the rise, the demand for transactions of secondhand digital content will grow in the future; thus, learning to make secure transactions while avoiding cyber attacks becomes an important issue. In this paper, we combine the new buyer's secret key, the new buyer's watermark to embed in resold digital content, and the reseller's encrypted watermark, which can prove legal ownership of the reseller. Using the privacy homomorphism property of RSA and exponential calculus, the original seller of digital content can verify the legality of the reseller and the new buyer. We also reduced the load of encryption/decryption digital content using a partial encryption/decryption algorithm to make our protocol more efficient and practical. In the proposed protocol, the seller is not able to conduct piracy and easily frame any other innocent secondhand buyer when a case of piracy is found. In fact, piracy can be clearly traced using the privacy homomorphism property of RSA and the embedded watermark mechanism. Further, in the proposed protocol, the seller himself can trace the piracy using exponential calculus. Since it is unnecessary to trust third party participation, the conspiracy problem is resolved and the new buyer is not required to participate in the dispute. Moreover, the seller, reseller and new buyer can simultaneously benefit from the secondhand transaction.