ACTA issues

A characterization theorem for matrix variances

Dénes Petz, Dániel Virosztek

Acta Sci. Math. (Szeged) 80:3-4(2014), 681-687

Abstract. Some recent papers formulated sufficient conditions for the decomposition of matrix variances [LZ-PD, PD-TG]. A statement was that if we have one or two observables, then the decomposition is possible. In this paper we consider an arbitrary finite set of observables and we present a necessary and sufficient condition for the decomposition of the matrix variances.

DOI: 10.14232/actasm-013-789-z

AMS Subject Classification (1991): 81Q10

Keyword(s): matrix

Received July 1, 2013, and in final form December 12, 2013. (Registered under 39/2013.)