A noncommutative extended de Finetti theorem

作者：Koestler Claus

来源：Journal of Functional Analysis, 2010, 258(4): 1073-1120.

DOI：10.1016/j.jfa.2009.10.021

• Noncommutative de Finetti theorem
• Distributional symmetries
• Exchangeability
• Spreadability
• Noncommutative conditional independence
• Mean ergodic theorem
• Noncommutative Kolmogorov zero-one law
• Noncommutative Bernoulli shifts

The extended de Finetti theorem characterizes exchangeable infinite sequences of random variables its conditionally i.i.d. and shows that the apparently weaker distributional symmetry of spreadability is equivalent to exchangeability. Our main result is a noncommutative version of this theorem.
In contrast to the classical result Of Ryll-Nardzewski, exchangeability turns out to be stronger than spreadability for infinite sequences of noncommutative random variables. Out of our investigations emerges noncommutative conditional independence in terms of a von Neumann algebraic structure closely related to Popa's notion of commuting squares and Kummerer's generalized Bernoulli shifts. Our main result is applicable to classical probability, quantum probability, in particular free probability, braid group representations and Jones subfactors.

• 出版日期2010-2-15