Regularity and amenability conditions for uniform algebras

Abstract

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 on a (varying) dense open subset of the character space of $A$. We show that, for a separable uniform algebra $A$, if $A$ has bounded relative units at every point of a dense subset of the character space of $A$, then $A_{lc}$ is dense in $A$. We construct a separable, essential, regular uniform algebra $A$ on its character space $X$ such that every point of $X$ is a peak point for $A$, $A$ has bounded relative units at every point of a dense open subset of $X$ and yet $A$ is not weakly amenable. In particular, this shows that a continuous derivation from a separable, essential uniform algebra $A$ to its dual need not annihilate $A_{lc}$.