CDAM: Computational, Discrete and Applicable Mathematics@LSE

CDAM Research Report, LSE-CDAM-2009-06

May 2009

Contractability of the maximal ideal space of algebras of measures in a half-space

Amol Sasane

Let H be the canonical half space in Rⁿ, and let M(H) denote the Banach algebra of all complex Borel measures with support contained in M(H), with the usual addition and scalar multiplication, and with convolution *, and the norm being the total variation. It is shown that the maximal ideal space of M(H), equipped with the Gelfand topology, is contractible as a topological space. In particular, it follows that M(H) is a projective free ring. In fact, for all subalgebras R of M(H) that satisfy a certain mild condition, it is shown that the maximal ideal space of R is contractible. Several examples of such subalgebras are also given.

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		Phone: +44(0)-20-7955 7494. Fax: +44(0)-20-7955 6877. Email: info@maths.lse.ac.uk