Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4592383 | Journal of Functional Analysis | 2007 | 19 Pages |
Abstract
An analogue of Krein's extension theorem is proved for operator-valued positive definite functions on free groups. The proof gives also the parametrization of all extensions by means of a generalized type of Szegö parameters. One singles out a distinguished completion, called central, which is related to quasi-multiplicative positive definite functions. An application is given to factorization of noncommutative polynomials.
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