Journal of Linear and Topological Algebra

55-63

Authors: Mina Ettefagha and Sima Houdfar

In this paper by using some conditions, we show that the weak amenability of (2n)-th dual of a Banach algebra A for some n ⩾ 1 implies the weak amenability of A.

69-77

Authors: M. Nili Ahmadabadi

In this paper, a fundamentally new method, based on the definition, is introduced for numerical computation of eigenvalues, generalized eigenvalues and quadratic eigenvalues of matrices. Some examples are provided to show the accuracy and reliability of the proposed method. It is shown that the proposed method gives other sequences than that of existing methods but they still are convergent to the desired eigenvalues, generalized eigenvalues and quadratic eigenvalues of matrices. These examples show an interesting phenomenon in the procedure: The diagonal matrix that converges to eigenvalues gives them in decreasing order in the sense of absolute value. Appendices A to C provide Matlab codes that implement the

91-104

Authors: M. Amirfakhrian and F. Mohammad

In this paper, we represent an inexact inverse subspace iteration method for com- puting a few eigenpairs of the generalized eigenvalue problem Ax = Bx[Q. Ye and P. Zhang, Inexact inverse subspace iteration for generalized eigenvalue problems, Linear Algebra and its Application, 434 (2011) 1697-1715 ]. In particular, the linear convergence property of the inverse subspace iteration is preserved.

1-7

Authors: Abasalt Bodaghi and Behrouz Shojaee

Let n 2 N. An additive map h : A --> B between algebras A and B is called n-Jordan homomorphism if h(an) = (h(a))n for all a 2 A. We show that every n-Jordan ho- momorphism between commutative Banach algebras is a n-ring homomorphism when n < 8. For these cases, every involutive n-Jordan homomorphism between commutative C^*-algebras is norm continuous.

15-20

Authors: Shervin Sahebi and Venus Rahmani

Let R be a prime ring with extended centroid C, H a generalized derivation of R and n ⩾ 1 a fixed integer. In this paper we study the situations: (1) If (H(xy))n = (H(x))n(H(y))n for all x; y 2 R; (2) obtain some related result in case R is a noncommutative Banach algebra and H is continuous or spectrally bounded.

27-32

Authors: P. Nosratpour and M. R. Darafshehb

Let L := U3(11). In this article, we classify groups with the same order and degree pattern as an almost simple group related to L. In fact, we prove that L, L:2 and L:3 are OD-characterizable, and L:S3 is 5-fold OD-characterizable.

41-44

Authors: M. Maghasedi

For a nite group G the commutativity degree denote by d(G) and dend: d(G) = jf(x; y)jx; y 2 G; xy = yxgj jGj2 : In [2] authors found commutativity degree for some groups,in this paper we nd commuta- tivity degree for a class of groups that have high nilpontencies.