Robin Havea

A Constructive Version of the Spectral Mapping Theorem

The spectral mapping theorem in a unital Banach algebra is examined for its constructive content.

Square roots and powers in constructive banach algebra theory

Several new and improved results about positive integral powers of hermitian elements, and square roots of positive elements, in a Banach algebra are proved constructively.

Separation properties in neighbourhood and quasi-apartness spaces

We investigate separation properties for neighbourhood spaces in some details within a framework of constructive mathematics, and define corresponding separation properties for quasi-apartness spaces. We also deal with separation properties for spaces with inequality. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)