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It was once conjectured that if $A$ is a uniform algebra on its maximal ideal space $X$, and if each point of $X$ is a peak point for $A$, then $A = C(X)$. This peak-point conjecture was disproved by Brian Cole in 1968. Here we establish a…

Complex Variables · Mathematics 2017-07-05 John T. Anderson , Alexander J. Izzo

It is shown that there exists a compact planar set K such that the uniform algebra R(K) is nontrivial and strongly regular. This settles an issue raised by Donald Wilken 55 years ago. It is shown that the set K can be chosen such that, in…

Complex Variables · Mathematics 2025-01-03 Alexander J. Izzo

We prove the existence of a nontrivial uniform algebra that is logmodular and regular on the Cantor set. As a consequence, we obtain that for every compact metrizable space X without isolated points there exists a nontrivial essential…

Complex Variables · Mathematics 2025-12-02 J. F. Feinstein , Alexander J. Izzo

In \cite{F} J.F. Feinstein constructed a compact plane set $X$ such that $R(X)$ has no non-zero, bounded point derivations but is not weakly amenable. In the same paper he gave an example of a separable uniform algebra $A$ such that every…

Functional Analysis · Mathematics 2007-05-23 M. J. Heath

A survey is given of the work on strong regularity for uniform algebras over the last thirty years, and some new results are proved, including the following. Let A be a uniform algebra on a compact space X and let E be the set of all those…

Functional Analysis · Mathematics 2007-05-23 J. F. Feinstein , D. W. B. Somerset

It is shown that there exists a nontrivial uniform algebra that is Dirichlet on its maximal ideal space and has a dense set of elements that are exponentials. This answers a 65-year-old question of John Wermer and a 17-year-old question of…

Complex Variables · Mathematics 2025-12-23 Alexander J. Izzo

We give a survey of the known connections between regularity conditions and amenability conditions in the setting of uniform algebras. For a uniform algebra $A$ we consider the set, $A_{lc}$, of functions in $A$ which are locally constant…

Functional Analysis · Mathematics 2014-12-25 M. J. Heath , J. F. Feinstein

For every algebraically closed field $\boldsymbol k$ of characteristic different from $2$, we prove the following: (1) Generic finite dimensional (not necessarily associative) $\boldsymbol k$-algebras of a fixed dimension, considered up to…

Algebraic Geometry · Mathematics 2015-01-20 Vladimir L. Popov

Regular groups and fields are common generalizations of minimal and quasi-minimal groups and fields, so the conjectures that minimal or quasi-minimal fields are algebraically closed have their common generalization to the conjecture that…

Logic · Mathematics 2012-11-19 Tomasz Gogacz , Krzysztof Krupinski

The peak algebra is a unital subalgebra of the symmetric group algebra, linearly spanned by sums of permutations with a common set of peaks. By exploiting the combinatorics of sparse subsets of [n-1] (and of certain classes of compositions…

Combinatorics · Mathematics 2016-09-07 Marcelo Aguiar , Kathryn Nyman , Rosa Orellana

The most important uniform algebra is the family of continuous functions on a compact subset $K$ of the complex plane $\mathbb{C}$ which are analytic on the interior int$(K)$ For compact sets $K$ which are regular (i.e. $K =$int$(K)$ and…

Complex Variables · Mathematics 2019-05-08 Abtin Daghighi , Paul M. Gauthier

We investigate the completeness and completions of the normed algebras $D^{(1)}(X)$ for perfect, compact plane sets $X$. In particular, we construct a radially self-absorbing, compact plane set $X$ such that the normed algebra $D^{(1)}(X)$…

Functional Analysis · Mathematics 2015-01-19 J. F. Feinstein , H. G. Dales

In a previous paper the second author introduced a compact topology on the space of closed ideals of a unital Banach algebra A. If A is separable then this topology is either metrizable or else neither Hausdorff nor first countable. Here it…

Functional Analysis · Mathematics 2007-05-23 J. F. Feinstein , D. W. B. Somerset

We compare two known methods of extending a complex, unital, commutative normed algebra so as to include solutions to sets of monic polynomials over the original algebra. (One of these is a generalisation of a construction from the thesis…

Functional Analysis · Mathematics 2007-05-23 Thomas Dawson

We strengthen, in various directions, the theorem of Garnett that every $\sigma$-compact, completely regular space $X$ occurs as a Gleason part for some uniform algebra. In particular, we show that the uniform algebra can always be chosen…

Complex Variables · Mathematics 2021-01-20 Alexander J. Izzo , Dimitris Papathanasiou

A general method for constructing essential uniform algebras with prescribed properties is presented. Using the method, the following examples are constructed: an essential, natural, regular uniform algebra on the closed unit disc; an…

Functional Analysis · Mathematics 2018-03-06 J. F. Feinstein , Alexander J. Izzo

It is shown that if $A$ is a uniform algebra generated by real-analytic functions on a suitable compact subset $K$ of a real-analytic variety such that the maximal ideal space of $A$ is $K$, and every continuous function on $K$ is locally a…

Complex Variables · Mathematics 2016-12-28 John T. Anderson , Alexander J. Izzo

We give a counterexample to a conjecture of S.E. Morris by showing that there is a compact plane set X such that R(X) has no non-zero, bounded point derivations but such that R(X) is not weakly amenable. We also give an example of a…

Functional Analysis · Mathematics 2007-05-23 J. F. Feinstein

We generalize some aspects of the theory of compact projections relative to a C*-algebra, to the setting of more general algebras. Our main result is that compact projections are the decreasing limits of `peak projections', and in the…

Operator Algebras · Mathematics 2012-03-19 David P. Blecher , Matthew Neal

A C*-algebra is said to be K-stable if its nonstable K-groups are naturally isomorphic to the usual K-theory groups. We study continuous $C(X)$-algebras, each of whose fibers are K-stable. We show that such an algebra is itself K-stable…

Operator Algebras · Mathematics 2020-05-11 Apurva Seth , Prahlad Vaidyanathan
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