• Honam Mathematical Journal
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• v.33 no.2
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• pp.143-152
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• 2011

In this paper, we prove some common fixed point theorems for finite number of discontinuous, non-compatible mapping on non-complete intuitionistic fuzzy metric spaces and obtain the example. Our research improve, extend and generalize several known results in intuitionistic fuzzy metric spaces.

• Communications of the Korean Mathematical Society
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• v.32 no.2
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• pp.375-387
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• 2017

In this paper, we prove some coincidence point theorems involving ${\varphi}-contraction$ in ordered partial metric spaces. We also extend newly introduced notion of g-comparability of a pair of maps for linear contraction in ordered metric spaces to non-linear contraction in ordered partial metric spaces. Thus, our results extend, modify and generalize some recent well known coincidence point theorems of ordered metric spaces.

• Journal of applied mathematics & informatics
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• v.27 no.1_2
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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.

• Bulletin of the Korean Mathematical Society
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• v.36 no.2
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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.

• Bulletin of the Korean Mathematical Society
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• v.50 no.4
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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.

• Communications of the Korean Mathematical Society
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• v.31 no.3
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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).

• The Pure and Applied Mathematics
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• v.16 no.1
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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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• v.15 no.2
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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.

• The Pure and Applied Mathematics
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• v.18 no.1
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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].

• Honam Mathematical Journal
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• v.6 no.1
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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.