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Vol.25 No.1

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Abstract

It is proved that 'maximum' is actually attained in the following risk measure representation <TEX>$${\rho}_m(X)={max \atop Q{\in}Q_m}E_Q[-X</TEX><TEX>]</TEX><TEX>$$</TEX>.

Kim, Insuk ; Jun, Sungtae pp.7-16 https://doi.org/10.7468/jksmeb.2018.25.1.7
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Abstract

The main objective of this paper is to demonstrate how one can obtain very quickly so far unknown Laplace transforms of rather general cases of the generalized hypergeometric function <TEX>$_3F_3$</TEX> by employing generalizations of classical summation theorems for the series <TEX>$_3F_2$</TEX> available in the literature. Several new as well known results obtained earlier by Kim et al. follow special cases of main findings.

Paek, Dae Hyun ; Shin, Yong Jin ; Yi, Jinhee pp.17-29 https://doi.org/10.7468/jksmeb.2018.25.1.17
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Abstract

We find modular equations of degree 3 to evaluate some new values of the cubic continued fraction <TEX>$G(e^{-{\pi}\sqrt{n}})$</TEX> and <TEX>$G(-e^{-{\pi}\sqrt{n}})$</TEX> for <TEX>$n={\frac{2{\cdot}4^m}{3}}$</TEX>, <TEX>${\frac{1}{3{\cdot}4^m}}$</TEX>, and <TEX>${\frac{2}{3{\cdot}4^m}}$</TEX>, where m = 1, 2, 3, or 4.

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Abstract

In [4], the authors show that if <TEX>${\mathbb{X}}$</TEX> is a <TEX>${\mathbb{k}}-configuration$</TEX> in <TEX>${\mathbb{P}}^2$</TEX> of type (<TEX>$d_1$</TEX>, <TEX>${\ldots}$</TEX>, <TEX>$d_s$</TEX>) with <TEX>$d_s$</TEX> > <TEX>$s{\geq}2$</TEX>, then <TEX>${\Delta}H_{m{\mathbb{X}}}(md_s-1)$</TEX> is the number of lines containing exactly <TEX>$d_s-points$</TEX> of <TEX>${\mathbb{X}}$</TEX> for <TEX>$m{\geq}2$</TEX>. They also show that if <TEX>${\mathbb{X}}$</TEX> is a <TEX>${\mathbb{k}}-configuration$</TEX> in <TEX>${\mathbb{P}}^2$</TEX> of type (1, 2, <TEX>${\ldots}$</TEX>, s) with <TEX>$s{\geq}2$</TEX>, then <TEX>${\Delta}H_{m{\mathbb{X}}}(m{\mathbb{X}}-1)$</TEX> is the number of lines containing exactly s-points in <TEX>${\mathbb{X}}$</TEX> for <TEX>$m{\geq}s+1$</TEX>. In this paper, we explore a standard <TEX>${\mathbb{k}}-configuration$</TEX> in <TEX>${\mathbb{P}}^2$</TEX> and find that if <TEX>${\mathbb{X}}$</TEX> is a standard <TEX>${\mathbb{k}}-configuration$</TEX> in <TEX>${\mathbb{P}}^2$</TEX> of type (1, 2, <TEX>${\ldots}$</TEX>, s) with <TEX>$s{\geq}2$</TEX>, then <TEX>${\Delta}H_{m{\mathbb{X}}}(m{\mathbb{X}}-1)=3$</TEX>, which is the number of lines containing exactly s-points in <TEX>${\mathbb{X}}$</TEX> for <TEX>$m{\geq}2$</TEX> instead of <TEX>$m{\geq}s+1$</TEX>.

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Abstract

In this work, by applying the binomial expansion, some refinements of the Young and Heinz inequalities are proved. As an application, a determinant inequality for positive definite matrices is obtained. Also, some operator inequalities around the Young's inequality for semidefinite invertible matrices are proved.

Moazzen, Alireza ; Gordji, Madjid Eshaghi ; Raeisi, Hamidreza pp.49-57 https://doi.org/10.7468/jksmeb.2018.25.1.49
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Abstract

We have introduced two new notions of convexity and closedness in functional analysis. Let X be a real normed space, then <TEX>$C({\subseteq}X)$</TEX> is functionally convex (briefly, F-convex), if <TEX>$T(C){\subseteq}{\mathbb{R}}$</TEX> is convex for all bounded linear transformations <TEX>$T{\in}B$</TEX>(X, R); and <TEX>$K({\subseteq}X)$</TEX> is functionally closed (briefly, F-closed), if <TEX>$T(K){\subseteq}{\mathbb{R}}$</TEX> is closed for all bounded linear transformations <TEX>$T{\in}B$</TEX>(X, R). By using these new notions, the Alaoglu-Bourbaki-Eberlein-<TEX>${\check{S}}muljan$</TEX> theorem has been generalized. Moreover, we show that X is reflexive if and only if the closed unit ball of X is F-closed. James showed that for every closed convex subset C of a Banach space X, C is weakly compact if and only if every <TEX>$f{\in}X^{\ast}$</TEX> attains its supremum over C at some point of C. Now, we show that if A is an F-convex subset of a Banach space X, then A is bounded and F-closed if and only if every element of <TEX>$X^{\ast}$</TEX> attains its supremum over A at some point of A.

Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics