Convex combinations of unitaries in JB∗-algebras
نویسندگان
چکیده
We continue our recent efforts to exploit the notion of a unitary isotope to study convex combinations of unitaries in an arbitrary JB∗-algebra. Exact analogues of C∗-algebraic results, due to R. V. Kadison, C. L. Olsen and G. K. Pedersen, are proved for general JB∗-algebras. We show that if a contraction in a JB∗-algebra is a convex combination of n unitaries, then it is also a mean of n unitaries. This generalizes a well known theorem of Kadison and Pedersen. Our methods also provide alternative proofs of other results for C∗-algebras.
منابع مشابه
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