scholarly journals A non-standard ideal of a radical Banach algebra of power series

1984 ◽  
Vol 152 (0) ◽  
pp. 199-217 ◽  
Author(s):  
Marc P. Thomas
Keyword(s):  
Power Series ◽  
Banach Algebra ◽  
Standard Ideal

scholarly journals Completion of normed algebras of polunomials

1975 ◽  
Vol 20 (4) ◽  
pp. 504-510 ◽  
Author(s):  
H. G. Dales ◽  
J. P. McClure
Keyword(s):  
Power Series ◽  
Banach Algebra ◽  
Formal Power Series ◽  
Complex Field ◽  
Linear Functionals ◽  
Bounded Linear ◽  
One To One ◽  
Formal Power

Let P be the algebra of polynomials in one inderminate x over the complex field C. Suppose ∥ · ∥ is a norm on P such that the coefficient functionals cj: ∑αix1 → αj (j = 0,1,2,…) are all continuous with respect to ∥·∥, and Let K ⊂ C be the set of characters on P which are ∥·∥-continuous. then K is compact, C\K is connected, and 0∈K. K. Let A be the completion of P with respect to ∥·∥. Then A is a singly generated Banach algebra, with space of characters (homeomorphic with) K. The functionals cj have unique extensions to bounded linear functionals on A, and the map a →∑Ci(a)xi (a ∈ A) is a homomorphism from A onto an algebra of formal power series with coefficients in C. We say that A is an algebra of power series if this homomorphism is one-to-one, that is if a ∈ A and a≠O imply cj(a)≠ 0 for some j.

scholarly journals Inequalities Of Lipschitz Type For Power Series In Banach Algebras

2015 ◽  
Vol 29 (1) ◽  
pp. 61-83
Author(s):  
Sever S. Dragomir
Keyword(s):  
Power Series ◽  
Banach Algebra ◽  
Banach Algebras ◽  
Open Disk ◽  
Complex Coefficients

AbstractLet $f(z) = \sum\nolimits_{n = 0}^\infty {\alpha _n z^n }$ be a function defined by power series with complex coefficients and convergent on the open disk D (0, R) ⊂ ℂ, R > 0. For any x, y ∈ ℬ, a Banach algebra, with ‖x‖, ‖y‖ < R we show among others that $$\left\| {f(y) - f(x)} \right\| \le \left\| {y - x} \right\|\int_0^1 {f_a^\prime } (\left\| {(1 - t)x + ty} \right\|)dt$$ where $f_a (z) = \sum\nolimits_{n = 0}^\infty {|\alpha _n |} \;z^n$ . Inequalities for the commutator such as $$\left\| {f(x)f(y) - f(y)f(x)} \right\| \le 2f_a (M)f_a^\prime (M)\left\| {y - x} \right\|,$$ if ‖x‖, ‖y‖ ≤ M < R, as well as some inequalities of Hermite–Hadamard type are also provided.

scholarly journals Positioning matrices with respect to the boundary of the maximal group

1986 ◽  
Vol 33 (1) ◽  
pp. 113-122
Author(s):  
J. DeFranza ◽  
D.J. Fleming
Keyword(s):  
Power Series ◽  
Banach Algebra ◽  
Finite Type ◽  
Maximal Group ◽  
Nörlund Means ◽  
Invertible Elements

Let Δ denote the Banach algebra of all conservative triangular matrics, M the maximal group of invertible elements of Δ, B the boundary of M and . In this note little Nörlund means are located with respect to the disjoint decomposition M u B u N of Δ in terms of the zeros of the generating power series. Further, corridor matrices of finite type, that is, conservative methods with finitely many convergent diagonals, are located with respect to M u B u N.

Formal Power Series Over Commutative N-Algebras

1978 ◽  
Vol 30 (01) ◽  
pp. 66-84 ◽  
Author(s):  
Ernst August Behrens
Keyword(s):  
Power Series ◽  
Banach Algebra ◽  
Formal Power Series ◽  
Compact Hausdorff Space ◽  
Hausdorff Space ◽  
Identity Element ◽  
Closed Ideal ◽  
Supremum Norm ◽  
Maximal Ideals ◽  
Formal Power

A Banach algebra P over C with identity element is called an N-algebra if any closed ideal in P is the intersection of maximal ideals. An example is given by the algebra of the continuous C-valued functions on a compact Hausdorff space X under the supremum norm; two others are discussed in § 3.

scholarly journals Continuity of derivations on topological algebras of power series

1969 ◽  
Vol 1 (3) ◽  
pp. 419-424 ◽  
Author(s):  
R.J. Loy
Keyword(s):  
Power Series ◽  
Banach Algebra ◽  
Formal Power Series ◽  
Topological Algebra ◽  
Fréchet Space ◽  
Frechet Space ◽  
Complex Field ◽  
Topological Algebras ◽  
Space Topology ◽  
Formal Power

Let A be an algebra of formal power series in one indeterminate over the complex field, D a derivation on A. It is shown that if A has a Fréchet space topology under which it is a topological algebra, then D is necessarily continuous provided the coordinate projections satisfy a certain equicontinuity condition. This condition is always satisfied if A is a Banach algebra and the projections are continuous. A second result is given, with weaker hypothesis on the projections and correspondingly weaker conclusion.

scholarly journals Topologically simple Banach algebras with derivation

1999 ◽  
Vol 60 (1) ◽  
pp. 153-161
Author(s):  
El Hossein Illoussamen ◽  
Volker Runde
Keyword(s):  
Power Series ◽  
Banach Algebra ◽  
Banach Algebras ◽  
Pivotal Role ◽  
Automatic Continuity

It is not known if a commutative, topologically simple, radical Banach algebra exists. If, however, every derivation on such an algebra is continuous, this yields the automatic continuity of all derivations on commutative, semiprime Banach algebras. Utilising techniques used by Thomas in his proof of the Singer-Wermer conjecture, we show that, if A is a commutative, topologically simple Banach algebra with a non-zero derivation on it, then a quotient of a certain localisation of A has a power series structure. A pivotal role is played by what we call ample sets of denominators.

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