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Characteristic functions for multicontractions and automorphisms of the unit ball

Chafiq Benhida·Dan Timotin
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Abstract

A \emph{multicontraction} on a Hilbert space $\HH$ is an $n$-tuple of operators $T=(T_1,...,T_n)$ acting on $\HH$, such that $\sum_{i=1}^n T_i T_i^*\le \1_\HH$. We obtain some results related to the characteristic function of a commuting multicontraction, most notably discussing its behaviour with respect to the action of the analytic automorphisms of the unit ball.

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Chafiq Benhida, Dan Timotin. 2005-09-05. Characteristic functions for multicontractions and automorphisms of the unit ball. https://arxiv.org/abs/math/0509094

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