On Singer-Wermer conjecture in Frechet algebras

Abstract

We construct two Frechet algebras admitting countably many mutually inequivalent Frechet algebra topologies. The second example is a modification of the maiden (and first) example of a non-Banach Frechet algebra with two inequivalent Frechet algebra topologies, considered by Read to show that the famous Singer-Wermer conjecture does not hold in the Frechet case. However the conjecture does hold by the second example which also admits countably many mutually equivalent Frechet algebra topologies.