Intermediate rings of complex-valued continuous functions

Abstract

Let $\Sigma (X,\mathbb{C})$ denote the collection of all the rings between $C^{\ast }(X,\mathbb{C})$ and $C(X,\mathbb{C})$. We show that there is a natural correlation between the absolutely convex ideals/ prime ideals/maximal ideals/$z$-ideals/$z^{\circ }$-ideals in the rings $P(X,\mathbb{C})$ in $\Sigma (X,\mathbb{C})$ and in their real-valued counterparts $P(X,\mathbb{C})\cap C(X)$. It is shown that the structure space of any such $P(X,\mathbb{C})$ is $\beta X$. We show that for any maximal ideal $M$ in $C(X,\mathbb{C}),C(X,\mathbb{C})/M$ is an algebraically closed field. We give a necessary and sufficient condition for the ideal $C_{\mathcal{P}}(X,\mathbb{C})$ of $C(X,\mathbb{C})$ to be a prime ideal, and we examine a few special cases thereafter.