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arXiv · 2311.01481

Group of automorphisms for strongly quasi invariant states

Ameur Dhahri·Chul Ki Ko·Hyun Jae Yoo
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Abstract

For a $*$-automorphism group $G$ on a $C^*$- or von Neumann algebra, we study the $G$-quasi invariant states and their properties. The $G$-quasi invariance or $G$-strongly quasi invariance are weaker than the $G$-invariance and have wide applications. We develop several properties for $G$-strongly quasi invariant states. Many of them are the extensions of the already developed theories for $G$-invariant states. Among others, we consider the relationship between the group $G$ and modular automorphism group, invariant subalgebras, ergodicity, modular theory, and abelian subalgebras. We provide with some examples to support the results.

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Ameur Dhahri, Chul Ki Ko, Hyun Jae Yoo. 2025-02-05. Group of automorphisms for strongly quasi invariant states. https://arxiv.org/abs/2311.01481

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