Extreme positive functionals
Extreme Spectral States of Commutative Banach Algebras.
Finitely generated maximum modulus algebras
Fréchet algebras and formal power series
The class of elements of locally finite closed descent in a commutative Fréchet algebra is introduced. Using this notion, those commutative Fréchet algebras in which the algebra ℂ[[X]] may be embedded are completely characterized, and some applications to the theory of automatic continuity are given.
Fréchet algebras, formal power series, and automatic continuity
We describe all those commutative Fréchet algebras which may be continuously embedded in the algebra ℂ[[X]] in such a way that they contain the polynomials. It is shown that these algebras (except ℂ[[X]] itself) always satisfy a certain equicontinuity condition due to Loy. Using this result, some applications to the theory of automatic continuity are given; in particular, the uniqueness of the Fréchet algebra topology for such algebras is established.
Fréchet algebras generated by certain of their elements.
Fredholm multipliers of semisimple commutative Banach algebras.
In some recent papers ([1],[2],[3],[4]) we have investigated some general spectral properties of a multiplier defined on a commutative semi-simple Banach algebra. In this paper we expose some aspects concerning the Fredholm theory of multipliers.
Fredholm Theory Relative to a Banach Algebra Homomorphism.
Functionals on Banach Algebras with Scattered Spectra
Let A be a complex, commutative Banach algebra and let be the structure space of A. Assume that there exists a continuous homomorphism h:L¹(G) → A with dense range, where L¹(G) is a group algebra of the locally compact abelian group G. The main results of this note can be summarized as follows: (a) If every weakly almost periodic functional on A with compact spectra is almost periodic, then the space is scattered (i.e., has no nonempty perfect subset). (b) Weakly almost periodic functionals...
Funktionetheoretische Hilfsmittel in der Theorie der kommutativen Banach-Algebren.
Funtional Boundedness of Some M-Complete m-Convex Algebras
Generators of maximal left ideals in Banach algebras
In 1971, Grauert and Remmert proved that a commutative, complex, Noetherian Banach algebra is necessarily finite-dimensional. More precisely, they proved that a commutative, complex Banach algebra has finite dimension over ℂ whenever all the closed ideals in the algebra are (algebraically) finitely generated. In 1974, Sinclair and Tullo obtained a non-commutative version of this result. In 1978, Ferreira and Tomassini improved the result of Grauert and Remmert by showing that the statement...
Hadamard's multiplication theorem - recent developments
Homomorphisms of commutative Banach algebras and extensions to multiplier algebras with applications to Fourier algebras
Let A and B be semisimple commutative Banach algebras with bounded approximate identities. We investigate the problem of extending a homomorphism φ: A → B to a homomorphism of the multiplier algebras M(A) and M(B) of A and B, respectively. Various sufficient conditions in terms of B (or B and φ) are given that allow the construction of such extensions. We exhibit a number of classes of Banach algebras to which these criteria apply. In addition, we prove a polar decomposition for homomorphisms from...
Homotonic algebras
An algebra 𝓐 of real- or complex-valued functions defined on a set T shall be called homotonic if 𝓐 is closed under taking absolute values, and for all f and g in 𝓐, the product f × g satisfies |f × g| ≤ |f| × |g|. Our main purpose in this paper is two-fold: to show that the above definition is equivalent to an earlier definition of homotonicity, and to provide a simple inequality which characterizes submultiplicativity and strong stability for weighted sup norms on homotonic algebras.
Invariance properties of homomorphisms on algebras of holomorphic functions with the Hadamard product
Let be the set of all holomorphic functions on the domain Two domains and are called Hadamard-isomorphic if and are isomorphic algebras with respect to the Hadamard product. Our main result states that two admissible domains are Hadamard-isomorphic if and only if they are equal.
Inverse elements in extensions of Banach algebras
Jointly prescalar sets in Banach algebras
Kommutative Banachalgebren und hermitesch-äquivalente Elemente
Korovkinhüllen in Funktionenräumen.