• Journal of the Korean Mathematical Society
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• v.40 no.5
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• pp.789-830
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• 2003

By forming completions of families of noncommutative polynomials, we define a notion of noncommutative continuous function and locally bounded Borel function that give a noncommutative analogue of the functional calculus for elements of commutative $C^{*}$-algebras and von Neumann algebras. These notions give a precise meaning to $C^{*}$-algebras defined by generator and relations and we show how they relate to many parts of operator and operator algebra theory.

• Journal of KIISE:Software and Applications
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• v.31 no.5
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• pp.658-666
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• 2004

Separable systems are defined in term rewriting systems, respecting the notion of separability in the λ-calculus. In this research, we generalize separable systems of term rewriting systems, which was studied in restrictive systems such as constructive systems. We also associate separability with index-transitivity and with forward branching Separability is identified with forward branching, and strong sequentiality with index-transitivity satisfies separability. These are such good properties that enable us to describe the procedure of pattern-matching as an index tree, which is a sort of automata, and to transform separable systems into a constructor system with a simple pattern. Separable systems, in particular, can be translated into the λ-calculus. This research can serve a theoretical basis which allows functional languages to be explained by the λ-calculus, since functional languages such as ML and Haskell belong to a subclass of separable systems.

• Nonlinear Functional Analysis and Applications
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• v.28 no.4
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• pp.1069-1086
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• 2023

The natural transform is represented by two (p, q)-analogues, and their comparative characteristics are established. To resolve some (p, q)-difference and functional equations, applications are carried out.

• Nonlinear Functional Analysis and Applications
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• v.28 no.4
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• pp.1115-1125
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• 2023

This paper deals with the controllability of linear and nonlinear generalized fractional dynamical systems in finite dimensional spaces. The results are obtained by using fractional calculus, Mittag-Leffler function and Schauder's fixed point theorem. Observability of linear system is also discussed. Examples are given to illustrate the theory.

• Journal of the Chungcheong Mathematical Society
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• v.29 no.1
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• pp.73-82
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• 2016

The utility of exponential generating functions is that they are relevant for combinatorial problems involving sets and subsets. Sequences of polynomials play a fundamental role in applied mathematics, such sequences can be described using the exponential generating functions. The actuarial polynomials ${\alpha}^{({\beta})}_n(x)$, n = 0, 1, 2, ${\cdots}$, which was suggested by Toscano, have the following exponential generating function: $${\limits\sum^{\infty}_{n=0}}{\frac{{\alpha}^{({\beta})}_n(x)}{n!}}t^n={\exp}({\beta}t+x(1-e^t))$$. A linear functional on polynomial space can be identified with a formal power series. The set of formal power series is usually given the structure of an algebra under formal addition and multiplication. This algebra structure, the additive part of which agree with the vector space structure on the space of linear functionals, which is transferred from the space of the linear functionals. The algebra so obtained is called the umbral algebra, and the umbral calculus is the study of this algebra. In this paper, we investigate some umbral representations in the actuarial polynomials.

• Communications of the Korean Mathematical Society
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• v.21 no.2
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• pp.293-320
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• 2006

Using calculus inequalities and embedding theorems in $R^1$, we establish $W^1_2$-estimates for the solutions of prey-predator population model with cross-diffusion and self-diffusion terms. Two cases are considered; (i) $d_1\;=\;d_2,\;{\alpha}_{12}\;=\;{\alpha}_{21}\;=\;0$, and (ii) $0\;<\;{\alpha}_{21}\;<\;8_{\alpha}_{11},\;0\;<\;{\alpha}_{12}\;<\;8_{\alpha}_{22}$. It is proved that solutions are bounded uniformly pointwise, and that the uniform bounds remain independent of the growth of the diffusion coefficient in the system. Also, convergence results are obtained when $t\;{\to}\;{\infty}$ via suitable Liapunov functionals.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.733-745
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• 1995

This study is aimed at construction of a translator for a functional programming language. For this goal we define a functional programming language which has lazy semantics and develop a translator for it. The execution model selected is the G-machine-based combinator graph reduction. The translator is composed of 4 phases and translates a source program to a C program. The first phase of the translator translates a source program to a enriched lambda- calculus graph, the second phase transforms a lambda-calculus graph into supercombinators, the third phase translates supercombiantors to a G program and the last phase translates the G program to a C program. The final result of the translator, a C program, is compiled to an executable program by C compiler. The translator is implemented in C using compiler development tools such as TACC and Lex, under the UNIX environments. In this paper we present the design and implementation techniques for developing the translator and show results by executing some test problems.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.22 no.1
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• pp.63-74
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• 2018

In this paper, we study the initial value problem for neutral functional differential equations involving Caputo fractional derivative of order ${\alpha}{\in}(0,1)$ with infinite delay. Some sufficient conditions for the uniqueness and continuous dependence of solutions are established by virtue of fractional calculus and Banach fixed point theorem. Some results obtained showed that the solution was closely related to the conditions of delays and minor changes in the problem. An example is provided to illustrate the main results.

• Journal of applied mathematics & informatics
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• v.31 no.1_2
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• pp.247-262
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• 2013

In this paper, using the time scale calculus theory, we first discuss the permanence of a $n$-species competition system with feedback control on time scales. Based on the permanence result, by the Lyapunov functional method, we establish sufficient conditions for the existence and uniformly asymptotical stability of almost periodic solutions of the considered model. The results of this paper is completely new. An example is employed to show the feasibility of our main result.

• Journal of the Korean Mathematical Society
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• v.35 no.3
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• pp.613-635
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• 1998

In this note we reformulate the white noise calculus on the classical Wiener space (C', C). It is shown that most of the examples and operators can be redefined on C without difficulties except the Hida derivative. To overcome the difficulty, we find that it is sufficient to replace C by L$_2$[0,1] and reformulate the white noise on the modified abstract Wiener space (C', L$_2$[0, 1]). The generalized white noise functionals are then defined and studied through their linear functional forms. For applications, we reprove the Ito formula and give the existence theorem of one-side stochastic integrals with anticipating integrands.