Journal of Linear and Topological Algebra
Year:2013 | Volume:2 | Issue:1|Papers Count:6

We survey the recent investigations on (bounded, sequential) approximate Connes amenability and pseudo-Connes amenability for dual Banach algebras. We will discuss the core problems concerning these notions and address the significance of any solutions to them to the development of the field.

Recently, Rahimi et al. [Comp. Appl. Math.2013, In press] defined the concept of quadrupled fixed point in K-metric spaces and proved several quadrupled fixed point theorems for solid cones on K-metric spaces. In this paper some quadrupled fixed point results for T -contraction on K-metric spaces without normality condition are proved. Obtained results extend and generalize well-known comparable results in the literature.

G-Frames in Hilbert spaces are a redundant set of operators which yield a representation for each vector in the space. In this paper we investigate the connection between g-frames, g-orthonormal bases and g-Riesz bases. We show that a family of bounded opera-tors is a g-Bessel sequences if and only if the Gram matrix associated to its defines a bounded operator.

In this paper we develop an approach that synthesizes the best features of the two main methods in the estimation of production efficiency. Specifically, our approach first allows for statistical noise, similar to Stochastic frontier analysis, and second, it allows modeling multiple-inputs-multiple-outputs technologies without imposing parametric assumptions on production relationship, similar to what is done in non-parametric methods. The methodology is based on the theory of local maximum likelihood estimation and extends recent works of Kumbhakar et al. We will use local-spherical coordinate system to transform multi-input multi-output data to more flexible system which we can use in our approach. We also illustrate the performance of our approach with simulated example.

In this paper we study the duality of Bessel and g -Bessel sequences in Hilbert spaces. We show that a Bessel sequence is an inner summand of a frame and the sum of any Bessel sequence with Bessel bound less than one with a Parseval frame is a frame. Next we develop this results to the g-frame situation.

In this paper, we investigate the reduced form of circulant matrices and we show that the problem of computing the q-th roots of a nonsingular circulant matrix A can be reduced to that of computing the q-th roots of two half size matrices B-C and B+C.