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Annihilators in JB-algebras

Published online by Cambridge University Press:  24 October 2008

M. Battaglia
Affiliation:
Universität Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland

Abstract

Orthogonality is defined for all elements in a JB-algebra and Topping's results on annihilators in JW-algebras are generalized to the context of JB- and JBW-algebras. A pair (a, b) of elements in a JB-algebra A is said to be orthogonal provided that a2b equals zero. It is shown that this relation is symmetric. The annihilator S of a subset S of A is defined to be the set of elements a in A such that, for all elements s in S, the pair (s, a) is orthogonal. It is shown that the annihilators are closed quadratic ideals and, if A is a JBW-algebra, a subset I of A is a w*-closed quadratic ideal if and only if I coincides with its biannihilator I⊥⊥. Moreover, in a JBW-algebra A the formation of the annihilator of a w*-closed quadratic ideal is an orthocomplementation on the complete lattice of w*-closed quadratic ideals which makes it into a complete orthomodular lattice. Further results establish a connection between ideals, central idempotents and annihilators in JBW-algebras.

Type
Research Article
Copyright
Copyright © Cambridge Philosophical Society 1990

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References

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