Factorization of Positive Invertible Operators in af Algebras

Huang, Houben ; Hudson, Timothy D.

Canadian journal of mathematics, Tome 47 (1995) no. 2, pp. 421-435

Résumé

We examine the problem of factoring a positive invertible operator in an AF C*-algebra as T*T for some invertible operator T with both T and T -1 in a triangular AF subalgebra. A factorization theorem for a certain class of positive invertible operators in AF algebras is proven. However, we explicitly construct a positive invertible operator in the CAR algebra which cannot be factored with respect to the 2∞ refinement algebra. Our main result generalizes this example, showing that in any AF algebra, there exist positive invertible operators which fail to factor with respect to a given triangular AF subalgebra. We also show that in the context of AF algebras, the notions of having a factorization and having a weak factorization are the same.

Détail

DOI : 10.4153/CJM-1995-023-0

Mots-clés : 46L05, 47D25

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