On the joint spectral radii of commuting Banach algebra elements

Joint and Generalized Spectral Radius of Upper Triangular Matrices with Entries in a Unital Banach Algebra

In this paper, we discuss some properties of joint spectral {radius(jsr)} and  generalized spectral radius(gsr)  for a finite set of upper triangular matrices with entries in a Banach algebra and represent relation between geometric and joint/generalized spectral radius. Some of these are in scalar matrices, but  some are different. For example for a bounded set of scalar matrices,$Sigma$, $r_*...

Math 206: Banach Algebra and Spectral Theory

On the Banach Algebra

We give some properties of the Banach algebra of bounded operators (lp(α)) for 1≤ p≤∞, where lp(α)= (1/α)−1∗lp . Then we deal with the continued fractions and give some properties of the operator ∆h for h > 0 or integer greater than or equal to one mapping lp(α) into itself for p ≥ 1 real. These results extend, among other things, those concerning the Banach algebra Sα and some results on the c...

Operator Radii of Commuting Products

Operator radii wp(T) for a bounded linear operator T on a Hubert space were introduced in connection with unitary p-dilations. We shall be concerned with universal estimates for the ratios wp(ST)/(wa(S)wl,(T)) for commuting operators S, T and o, p > 0. 1. All operators in this paper are bounded linear operators on a complex Hubert space §. We say an operator T belongs to the class G (0 < p < oo...

Elements in a Commutative Banach Algebra Determining the Norm Topology

For an element a of a commutative complex Banach algebra (A, ‖ · ‖) we investigate the following property: every complete norm | · | on A making the multiplication by a from (A, | · |) to itself continuous is equivalent to ‖ · ‖.