Theory of Approximation and Applications
Volume:1 Issue: 1, Spring 2005

The existence of non-fixed, almost translation invariant ultrafilters on any in¯nite semigroup S satisfying some algebraic properties is established using an ultra¯lter approach. The structure of the stone- ·Cech compacti¯cation of any discrete semigroup is investigated using filters and closed subsets of S.

A general interval linear system is investigated using the embedding approach. Conditions for the existence of a interval solution are derived and a numerical procedure for calculating the solution is designed. The proposed model is illustrated with examples.

This paper concern with inputs/outputs in the presence of non-discretionary variables. We discuss questions like this: suppose some inputs (outputs) are nondiscretionary and among a group of decision making units (DMUs) a DMU changes (increases and decreases simultaneously) some or all its output (input) levels. How much discretionary inputs (outputs) could the unit change such that its efficiency index remains unchanged? To solve the problem we propose a Multiple Objective Linear Programming (MOLP). Our MOLP model could estimate input/output levels, regardless of the efficiency or inefficiency of the DMU. We propose necessary and sufficient conditions for inputs/outputs estimation. A numerical example is then presented.

In this paper we investigate the equitable allocation of shared cost in data envelopment analysis (DEA). For this purpose we give a review of Cook and Kress [4] method for this allocation, they identified this allocation among a group of decision making units (DMUs) in terms of reduced cost and efficiency level of units. We show that their method is problematic and then we proposed an alternative approach for such allocations.

In this paper, we use the continuous Legendre wavelets on the interval [0, 1) to solve the liner integro-differential equation system

In this paper we represent a new method for solving a symmetric fuzzy linear system by two crisp linear systems. Also necessary and sufficient conditions for the solution existence are given.