• The Pure and Applied Mathematics
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• v.10 no.3
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• pp.145-161
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• 2003

Weak commutativity of a pair of maps was introduced by Sessa [On a weak commutativity condition of mappings in fixed point considerations. Publ. Inst. Math. (Beograd) (N.S.) 32(40) (1982),149-153] in fixed point considerations. Thereafter a number of generalizations of this notion has been obtained. The purpose of this paper is to present a brief development of weaker forms of commuting maps, and to obtain two fixed point theorems for noncommuting and noncontinuous maps on noncomplete metric spaces.

• Language and Information
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• v.11 no.1
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• pp.25-38
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• 2007

So-called multiple nominative constructions (MNCs) in Korean are quite theoretically as well as computationally puzzling. This paper shows that a grammar allowing the interaction of declarative constraints on types of signs - in particular, constructions (phrases and clauses)-can provide a robust and efficient way of encoding generalizations for two different MNCs. The feasibility of the grammar developed has been checked with its implementation into the LKB (Linguistic Knowledge Building) system.

• Bulletin of the Korean Mathematical Society
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• v.46 no.1
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• pp.147-153
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• 2009

In this paper, we give some constructions of implicative/commutative d-algebras which are not BCK-algebras. This demonstrate that the notion of implicative/commutative d-algebras are indeed generalizations of the same in BCK-algebras.

• Communications of the Korean Mathematical Society
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• v.34 no.3
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• pp.771-782
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• 2019

We show that mappings preserving unit distance are close to two-isometries. We also prove that a mapping f is a linear isometry up to translation when f is a two-expansive surjective mapping preserving unit distance. Then we apply these results to consider two-isometries between normed spaces, strictly convex normed spaces and unital $C^*$-algebras. Finally, we propose some remarks and problems about generalized two-isometries on Banach spaces.

• Kyungpook Mathematical Journal
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• v.59 no.2
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• pp.215-224
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• 2019

In the present paper, some generalizations of analytic functions have been considered and the bounds of the coefficients of these classes of bi-univalent functions have been investigated.

• Honam Mathematical Journal
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• v.41 no.3
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• pp.515-530
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• 2019

The concept of fuzzy sets in UP-algebras was first introduced by Somjanta et al. [Fuzzy sets in UP-algebras; 2016]. In this paper, we introduce and study fuzzy proper UP-filters of UP-algebras and prove their generalizations and characteristic fuzzy sets of proper UP-filters. Moreover, we discuss the relations between fuzzy proper UP-filters and their level subsets.

• Bulletin of the Korean Mathematical Society
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• v.56 no.3
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• pp.779-787
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• 2019

In this paper, we study two functional equations with two unknown functions from an Abelian group into a commutative ring without zero divisors. The two equations are generalizations of Swiatak's functional equations with an involution. We determine the general solutions of the two functional equations and the properties of the general solutions of the two functional equations under three different hypotheses, respectively. For one of the functional equations, we establish the Hyers-Ulam stability in the case that the unknown functions are complex valued.

• Kyungpook Mathematical Journal
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• v.59 no.1
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• pp.23-34
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• 2019

In this paper, we first define generalizations of Pell and Pell-Lucas sequences by the recurrence relations $$p_n=2ap_{n-1}+(b-a^2)p_{n-2}\;and\;q_n=2aq_{n-1}+(b-a^2)q_{n-2}$$ with initial conditions $p_0=0$, $p_1=1$, and $p_0=2$, $p_1=2a$, respectively. We give generating functions and Binet's formulas for these sequences. Also, we obtain some identities of these sequences.

• Annals of Fuzzy Mathematics and Informatics
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• v.16 no.3
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• pp.285-299
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• 2018

Many generalizations of ideals of a lattice to an arbitrary poset have been studied by different scholars. In this paper, we introduce several L-fuzzy ideals of a poset which generalize the notion of an L-fuzzy ideal of a lattice and give several characterizations of them.

• Korean Journal of Mathematics
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• v.29 no.2
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• pp.435-443
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• 2021

In this paper, we consider an operator N : 𝓟_n → 𝓟_n on the space of polynomials 𝓟_n of degree at most n and establish some compact generalizations of Bernstein-type polynomial inequalities, which include several well known polynomial inequalities as special cases.