• East Asian mathematical journal
• /
• v.24 no.1
• /
• pp.111-123
• /
• 2008

In this paper, we introduce a new system of first-order impulsive fuzzy differential equations. By using Banach fixed point theorem, we obtain some new existence and uniqueness theorems of solutions for this system of first-order impulsive fuzzy differential equations in the metric space of normal fuzzy convex sets with distance given by maximum of the Hausdorff distance between level sets.

• Honam Mathematical Journal
• /
• v.30 no.4
• /
• pp.677-683
• /
• 2008

On a compact n-dimensional manifold M, it has been conjectured that a critical point metric of the total scalar curvature, restricted to the space of metrics with constant scalar curvature of volume 1, should be Einstein. The purpose of the present paper is to prove that a 3-dimensional manifold (M,g) is isometric to a standard sphere if ker $s^*_g{{\neq}}0$ and there is a lower Ricci curvature bound. We also study the structure of a compact oriented stable minimal surface in M.

• Journal of the Chungcheong Mathematical Society
• /
• v.15 no.1
• /
• pp.75-85
• /
• 2002

Let X be a compact metric space and let f be a continuous relation on X. Let U be an attractor block for f and let A bean attractor determined by U. Then there exists a continuous function ${\lambda}^{-1}:X{\rightarrow}[0,1]$ such that ${\lambda}^{-1}(0)=A$, ${\lambda}^{-1}(1)=X-B(A,U)$, and $M({\lambda},f)(x)$ < ${\lambda}(x)$ for all $x{\in}B(A,U)-A$.

• Journal of the Chungcheong Mathematical Society
• /
• v.15 no.1
• /
• pp.7-23
• /
• 2002

We introduce the notion of expansivity for a continuous surjection on a compact metric space, as the positively and negatively expansive map. We also prove that some well-known properties about positively expansive maps in [2] hold by using our definition.

• Journal of the Chungcheong Mathematical Society
• /
• v.28 no.4
• /
• pp.647-651
• /
• 2015

Let (X, d) be a compact metric space, and let $f:X{\rightarrow}X$ be a continuous map. We consider that if a positively continuum-wise expansiveness continuous map f has the positively shadowing property in the nonwandering set, then the topological entropy is positive.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.21 no.1
• /
• pp.29-37
• /
• 2017

A general optimal recovery problem is to approximate a value of a linear operator on a subset (class) in linear space from a value of another linear operator (called information), measured with an error in given metric. We use this formulation to investigate the classical computerized tomography problem of inversion of the noisy Radon transform.

• Communications of the Korean Mathematical Society
• /
• v.35 no.4
• /
• pp.1255-1267
• /
• 2020

The class of isotropic almost complex structures, J_𝛿,𝜎, define a class of Riemannian metrics, g_𝛿,𝜎, on the tangent bundle of a Riemannian manifold which are a generalization of the Sasaki metric. This paper characterizes the metrics g_𝛿,0 using the geometry of tangent bundle. As a by-product, some integrability results will be reported for J_𝛿,𝜎.

• Communications of the Korean Mathematical Society
• /
• v.22 no.4
• /
• pp.575-586
• /
• 2007

We introduce here notions of chain recurrent sets, attractors and its basins for general dynamical systems and prove important properties including (i) the chain recurrent set CR(f) of f on a metric space (X, d) is the complement of the union of sets B(A) -A as A varies over the collection of attractors and (ii) genericity of general dynamical systems.

• Kyungpook Mathematical Journal
• /
• v.55 no.1
• /
• pp.205-218
• /
• 2015

In this paper, we introduce the concept of generalized c-distance on a cone metric space and prove some common fixed point and coincidence point results by using this notion. Our results generalize and extend several well known comparable results in the literature.

• Proceedings of the Korean Statistical Society Conference
• /
• 2001.11a
• /
• pp.137-141
• /
• 2001

We can obtain SLLN's for fuzzy random variables with respect to the new metric $d_s$ on the space F(R) of fuzzy numbers in R. In this paper, we obtain a SLLN for convex tight random elements taking values in F(R).