New York Journal of Mathematics
Volume 24 (2018) 43-51

  

Ameer Athavale

A multivariate generalization of the von Neumann-Wold decomposition

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Published: January 11, 2018
Keywords: Spherical isometry, q-hypercontraction
Subject: Primary 47A13

Abstract
Let H be a complex infinite-dimensional separable Hilbert space. If T is an isometry acting on H, then the von Neumann-Wold decomposition theorem asserts that T can be expressed as a direct sum of the unilateral shift (of some multiplicity) and a unitary operator. We establish a multivariate generalization of the von Neumann-Wold decomposition and explore some of the implications of that generalization. In particular we derive a universal representation theorem for members of a special class of spherical isometries and verify that any member of that class is hyperreflexive.

Author information

Department of Mathematics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
athavale@math.iitb.ac.in