• Journal of the Korean Society for information Management
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• v.21 no.2
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• pp.1-21
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• 2004

For the guarantee of retrieval ratio, thesaurus's maintenance for descriptors are necessary. To maintain the optimum scale of thesaurus, new terms and existing terms should be structured to the equivalence relationship. Therefore, equivalence relationships are needed to new standard. This study proposes new standard of the equivalence relationships, which is more specified for better guarantee of retrieval ratios. The relationships have seven facets. These six facets will be used as new knowledge-base, which could be reestablished between the descriptors.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.1
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• pp.100-111
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• 2007

We introduce the concept of intuitionistic fuzzy G-equivalence relations (congruence), and we obtain some results. Furthermore, we prove that $IFC_G(K)$ is isomorphic to $IFN^*(K)$ for any group K. Also, we prove that($IFC_{G,({\lambda},{\mu})}/{\sim},\;*$) and ($IFNG_{({\lambda},{\mu})}(K),\;{\circ}$) are isomorphic.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1699-1704
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• 1991

The states, inputs, outputs and parameters of a complex-system are all complex values. The introduction of such complex systems makes it more suitable to treat not only the robust control but also the pole assignment in the separate regions. The relation called "equivalence in the discrete sense" is introduced to define a complex-system corresponding to a real-system with real-axis poles as well as complex conjugate poles. The relation between the feedback-control laws of the equivalent systems in the discrete sense are derived so that their closed-loop systems should hold the equivalence in the discrete sense.ete sense.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.3
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• pp.425-431
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• 2009

By using the notion of interval-valued fuzzy relations, we forms the poset (IVFR (X), $\leq$) of interval-valued fuzzy relations on a given set X. In particular, we forms the subposet (IVFE (X), $\leq$) of interval-valued fuzzy equivalence relations on a given set X and prove that the poset (IVFE(X), $\leq$) is a complete lattice with the least element and greatest element.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.1
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• pp.145-152
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• 2011

By using the notion of interval-valued intuitionistic fuzzy relations, we form the poset (IVIR(X), $\leq$) of interval-valued intuitionistic fuzzy relations on a given set X. In particular, we form the subposet (IVIE(X), $\leq$) of interval-valued intuitionistic fuzzy equivalence relations on a given set X and prove that the poset (IVIE(X), $\leq$) is a complete lattice with the least element and greatest element.

• The Pure and Applied Mathematics
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• v.11 no.2
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• pp.127-132
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• 2004

$H_v$-rings first were introduced by Vougiouklis in 1990. The largest class of algebraic systems satisfying ring-like axioms is the $H_v$-ring. Let R be an $H_v$-ring and ${\gamma}_R$ the smallest equivalence relation on R such that the quotient $R/{\gamma}_R$, the set of all equivalence classes, is a ring. In this case $R/{\gamma}_R$ is called the fundamental ring. In this short communication, we study the fundamental rings with respect to the product of two fuzzy subsets.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.3
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• pp.557-569
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• 2013

In this paper we shall introduce the $f$-function in a set, and give some properties of $f$-function of a set. In particular, we establish a relation between $f$-function of a set and fuzzy equivalence relation. We also introduce the notion of $f$-homomorphism on a semigroup S, and prove the generalized fundamental homomorphism theorem of semigroup.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.409-420
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• 2006

In this paper we consider the set of all n + 1-tuples of real numbers, not necessarily all distinct, in the decreasing order from the unit interval under the usual ordering of real numbers, always including 1. Such n + 1-tuples inherently arise as the membership values of fuzzy subsets and are called keychains. An natural equivalence relation is introduced on this set and the equivalence classes of keychains are studied here. The number of such keychains is finite and the set of all keychains is a lattice under the coordinate-wise ordering. Thus keychains are subchains of a finite chain of real numbers in the unit interval. We study some of their properties and give some applications to counting fuzzy subsets of finite sets.

• Communications of the Korean Mathematical Society
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• v.32 no.2
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• pp.353-359
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• 2017

Starting from a t-norm T, it is possible to construct a class of new t-norms, so-called T-generalized t-norm. The purpose of this paper is to describe some properties of this class of generalized t-norms. An algebraic structure as well as a binary relation among t-norms are also investigated. Some open problems are discussed as well.

• Communications of the Korean Mathematical Society
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• v.23 no.4
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• pp.461-468
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• 2008

We define an $\epsilon$-fuzzy congruence, which is a weakened fuzzy congruence, find the $\epsilon$-fuzzy congruence generated by the union of two $\epsilon$-fuzzy congruences on a semigroup, and characterize the $\epsilon$-fuzzy congruences generated by fuzzy relations on semigroups. We also show that the collection of all $\epsilon$-fuzzy congruences on a semigroup is a complete lattice and that the collection of $\epsilon$-fuzzy congruences under some conditions is a modular lattice.