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arXiv · 1512.06321

On algebra-valued R-diagonal elements (with erratum)

March Boedihardjo·Ken Dykema
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Abstract

For an element in an algebra-valued *-noncommutative probability space, equivalent conditions for algebra-valued R-diagonality (a notion introduced by Sniady and Speicher) are proved. Formal power series relations involving the moments and cumulants of such R-diagonal elements are proved. Decompositions of algebra-valued R-diagonal elements into products of the form unitary times self-adjoint are investigated; sufficient conditions, in terms of cumulants, for *-freeness of the unitary and the self-adjoint part are proved, and a tracial example is given where *-freeness fails. The particular case of algebra-valued circular elements is considered; as an application, the polar decompostion of the quasinilpotent DT-operator is described. An erratum is appended. (The last sentence in the above paragraph is thereby nullified.)

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March Boedihardjo, Ken Dykema. 2015-12-20. On algebra-valued R-diagonal elements (with erratum). https://arxiv.org/abs/1512.06321

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