We obtain the time-dependent correlation function describing the evolution of a single spin excitation state in a linear spin chain with isotropic nearestneighbour XY coupling, where the Hamiltonian is related to the Jacobi matrix of a set of orthogonal polynomials. For the Krawtchouk polynomial case, an arbitrary element of the correlation function is expressed in a simple closed form. Its asy...

The Hahn–Banach Theorem plays a crucial role in the second fundamental theorem of welfare economics. To date, all mathematical economics and advanced general equilibrium textbooks concentrate on using non-constructive or incomputable versions of this celebrated theorem. In this paper we argue for the introduction of constructive or computable Hahn–Banach theorems in mathematical economics and a...

Se estudian perturbaciones de funcionales lineales (tanto en la recta real como en el ćırculo unidad) que pertenecen a la clase de Laguerre–Hahn. En particular, se obtiene una expresión para las funciones de Stieltjes y Carathéodory asociadas con los funcionales perturbados y se muestra que se preserva la clase de Laguerre–Hahn. Finalmente, se discute que bajo la transformación de Szegő la clas...

The idea behind this article is to provide a unified and relatively nontechnical framework for treating the main existence theorems for continuous linear functionals in functional analysis, convex analysis, Lagrange multiplier theory, and minimax theory. While many of the results in this article are already known, our approach is new, and gives a large number of results with considerable econom...

K.Balasubramanian , K. Chandrasekhara rao *2 Department of Mathematics, School of Humanities and Sciences, SASTRA University, Thanjavur 613402, India 1 [email protected] * Department of Mathematics, Srinivasa Ramanujan Centre, SASTRA University, Kumbakonam,India 2 [email protected] Abstract— This paper is devoted to the rate space of Hahn sequence space. It is denoted by . Some properti...