• Journal of applied mathematics & informatics
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• 제27권1_2호
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• pp.351-363
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• 2009

In this paper, we give some new definitions of $D^*$-metric spaces and we prove a common fixed point theorem for six mappings under the condition of weakly compatible mappings in complete $D^*$-metric spaces. We get some improved versions of several fixed point theorems in complete $D^*$-metric spaces.

• 대한수학회보
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• 제36권2호
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• pp.379-388
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• 1999

In this paper, we introduce a semi-metric on a normed almost linear space X via functional. And we prove that a normed almost linear space X is complete if and only if $V_X$ and $W_X$ are complete when X splits as X=$W_X$ + $V_X$. Also, we prove that the dual space $X^\ast$ of a normed almost linear space X is complete.

• 대한수학회보
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• 제50권4호
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• pp.1367-1376
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• 2013

We study Einstein lightlike hypersurfaces M of a Lorentzian space form $\tilde{M}(c)$ admitting a semi-symmetric non-metric connection subject to the conditions; (1) M is screen conformal and (2) the structure vector field ${\zeta}$ of $\tilde{M}$ belongs to the screen distribution S(TM). The main result is a characterization theorem for such a lightlike hypersurface.

• 대한수학회논문집
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• 제31권3호
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• pp.613-624
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• 2016

We define a new connection on a semi-Riemannian manifold. Its notion contains two well known notions; (1) semi-symmetric connection and (2) quarter-symmetric connection. In this paper, we study the geometry of lightlike hypersurfaces of an indefinite generalized Sasakian space form with a symmetric metric connection of type (${\ell}$, m).

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제16권1호
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• pp.19-30
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• 2009

In this paper, we prove some common fixed point theorems for six maps satisfying compatible maps of type(${\alpha}$) on intuitionistic fuzzy metric spaces in sense of Park et al.[7]. Our research are generalization and extension for the results of [1], [2], [3] and [13].

• East Asian mathematical journal
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• 제15권2호
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• pp.325-336
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• 1999

In this paper, we prove that any $\lambda$-firmly nonexpansive mapping ($0<\lambda<1)T:C{\rightarrow}C$ has a fixed point in C whenever C is a finite union of nonempty, bounded, closed and convex subsets of a metric space of hyperbolic type.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제18권1호
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• pp.13-29
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• 2011

In this paper, we introduce the new concept of ${\omega}-D^*$-distance on a $D^*$-metric space and prove a non-convex minimization theorem which improves the result of Caristi[1], ${\'{C}}iri{\'{c}}$[2], Ekeland[4], Kada et al.[5] and Ume[8, 9].

• 호남수학학술지
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• 제6권1호
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• pp.1-12
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• 1984

Let(X, $\Im$) be a probabilistic metric space with a t-norm. Common fixed point theorems and convergence theorems generalizing the results of Ćirić, Fisher, Sehgal, Istrătescu-Săcuiu and others are proved for three mappings P,S,T on X satisfying $F_{Pu, Pv}(qx){\geq}min\left{F_{Su,Tv}(x),F_{Pu,Su}(x),F_{Pv,Tv}(x),F_{Pu,Tv}(2x),F_{Pv,Su}(2x)\right}$ for every $u, v {\in}X$, all x>0 and some $q{\in}(0, 1)$. One of the main results is extended to uniform spaces. Mathematics Subject Classification (1980): 54H25.

• Journal of applied mathematics & informatics
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• 제8권2호
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• pp.551-560
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• 2001

In this paper, we investigate the continuity if addition and scalar multiplication on the space F(R/sup p/) of upper semicontinuous fuzzy sets in R/sup p/ under the Shorokhod metric.

• 대한수학회논문집
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• 제13권2호
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• pp.337-343
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• 1998

In this paper we show that every contact metric manifold with vanishing contact conformal curvature tensor is a Sasakian space form.