• Honam Mathematical Journal
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• v.41 no.4
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• pp.697-705
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• 2019

The article studies the concept of a (𝜑, 𝜓)-biflat and (𝜑, 𝜓)-amenable Banach algebra A, where 𝜑 is a continuous homomorphism on A and 𝜓 ∈ Φ_A. We show if A has a (𝜑, 𝜓)-virtual diagonal, then A is (𝜑, 𝜓)- biflat. In the case where 𝜑(A) is commutative we prove that (𝜑, 𝜓)- biflatness of A implies that A has a (𝜑, 𝜓)-virtual diagonal.

• Journal of applied mathematics & informatics
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• v.6 no.1
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• pp.217-226
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• 1999

In this paper we define automata-linearly independence. An automaton M has a basis B iff M is free provided that we assume that the action of S on X $\times$ S is (x,sa) for all a, s $\in$ S and x $\in$ X. if a semigroup S is PRID every subautomaton of a free S-automaton is free.

• Korean Journal of Mathematics
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• v.19 no.4
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• pp.409-421
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• 2011

We study a natural map from the braid group to the mapping class group which is called Harer map. It is rather new and different from the classical map which was studied in 1980's by F. Cohen, J. Harer et al. We show that this map is homologically trivial for most coefficients by using the fact that this map factors through the symmetric group.

• Communications of the Korean Mathematical Society
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• v.19 no.2
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• pp.219-232
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• 2004

We study relationships between closure operators and BL-algebras. We investigate the properties of closure operators and BL-homomorphisms on BL-algebras. We show that the image of a closure operator on a BL-algebra is isomorphic to a quotient BL-algebra.

• Journal of the Korean Mathematical Society
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• v.34 no.3
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• pp.673-693
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• 1997

In this work, the irreducible complex representations of degree 4 of $B_4$, the braid group on 4 strings, are classified. There are 4 families of representations: A two-parameter family of representations for which the image of $P_4$, the pure braid group on 4 strings, is abelian; two families of representations which are the composition of an irreducible representation of $B_3$, the braid group on 3 strings, with a certain special homomorphism $\pi : B_4 \longrightarrow B_3$; a family of representations which are the tensor product of 2 irreducible two-dimensional representations of $B_4$.

• Communications of the Korean Mathematical Society
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• v.31 no.3
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• pp.451-460
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• 2016

The notion of a rough fuzzy filter in a BE-algebra is introduced and some properties of such a filter are investigated. The relations between the upper (lower) rough filters and the upper (lower) approximations of their homomorphism images are discussed.

• Bulletin of the Korean Mathematical Society
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• v.57 no.3
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• pp.803-813
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• 2020

Let M be a finitely generated G-projective R-module over a PVMD R. We prove that M is projective if and only if the canonical map θ : M⨂_R M^∗ → Hom_R(Hom_R(M, M), R) is a surjective homomorphism. Particularly, if G-gldim(R) ⩽ ∞ and Extⁱ_R(M, M) = 0 (i ⩾ 1), then M is projective.

• Kyungpook Mathematical Journal
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• v.54 no.3
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• pp.471-476
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• 2014

Let R be a ring. A right R-module M is PS-injective if every R-homomorphism $f:aR{\rightarrow}M$ for every principally small right ideal aR can be extended to $R{\rightarrow}M$. We investigate, in this paper, rings whose simple singular modules are PS-injective. New characterizations of semiprimitive rings and semisimple Artinian rings are given.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.2
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• pp.156-160
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• 2001

In this paper we define fuzzy subsystems of a fuzzy finite state machine by using maps $S^{\alpha}$ of each state subset to its all $\alpha$-successors, which is a natural generalization of crisp submachines as fuzzy. And the corresponding concepts are also examined. also examined.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.3
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• pp.423-429
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• 2007

We define and study the fuzzy Jacobson radical of a ${\kappa}$-semiring. Also it is shown that the Jacobson radical of the quotient semiring R/FJR(R) of a ${\kappa}$-semiring by the fuzzy Jacobson radical FJR(R) is semisimple. And the algebraic properties of the fuzzy ideals FJR(R) and FJR(S) under a homomorphism from R onto S are also discussed.