سال:1388 | دوره: | شماره: |تعداد مقالات:8

In this paper, we study some main properties of the commuting regular ideals and we give a necessary and sufficient condition that a ring (or semi groups) is commuting regular. Some significant results of this investigation will be used for the commutative rings and group rings.

Banach algebra A is weakly amenable if every continuous derivation from A into A* is inner. In this paper, we show that the semi group algebra Ma(S) is weakly amenable for a certain class of locally compact semigroups.

The purpose of this research is to examine the effect of polarization for the problem of pure azimuthal shear of an elastic dielectric material. The present problem is investigated in context of finite deformation theory. In this paper, the author studied the effect of polarization on the stresses for Neoprene rubber and compare the results with elastic material (Mooney-Rivlin material) graphically. Twisting of a rigid cylinder in an infinite elastic medium is considered as a special case in this research.

The aim of this contribution is to establish and prove two general common fixed point theorems for four occasionally weakly compatible maps in a metric space. These results unify and complement several various results, especially the main result of Djoudi [2] and references therein.

In this paper we obtain a Presic type unique common fixed point theorem for three maps and obtain the main theorem of Ciric and Presic as corollary.

In this paper a bivariate rational interpolation is developed to create a space surface using both function values and the first order partial derivatives of the function being interpolated as the interpolation data. This method has some characteristics comparing with present interpolation methods. First, the interpolation function has a simple and explicit mathematical representation. Secondly, the interpolation function can be expressed by symmetric bases. We use this method to estimate the value of double integrals. Presented examples show the pertinent features of the method.

Let X be a hemicompact k-space and A be a uniform Frechet algebra on X. In this note we first show that if each element of a dense subset of A has square root in A then A=C(X) under certain condition. Then we show that G(C(X)), the group of invertible elements of C(X), is dense in C(X) if and only if dimX, the covering dimension of X, does not exceed 1. Using this result we give a necessary and sufficient condition under which each continuous function on X is the square of another

A lacunary sequence is an increasing sequence q=(kr) of positive integers such that  k0=0 and kr-kr−1 ®¥ as r®¥ In this  paper we introduce lacunary statistical convergence on probabilistic normed space (briefly PN spaces) and establish some inclusion relations between the sets of statistically convergent and lacunary statistically convergent sequences on PN spaces. We also defined lacunary statistical Cauchy sequence in these spaces and prove that it is equivalent to lacunary statistical convergent sequence