A. V. Dudko | Searcharxiv

arXiv2009

Invariant states on the wreath product

Let $\mathfrak{S}_\infty$ be the infinity permutation group and $Γ$ be a separable topological group. The wreath product $Γ\wr \mathfrak{S}_\infty$ is the semidirect product $Γ^\infty_e \rtimes \mathfrak{S}_\infty$ for the usual permutation action of $\mathfrak{S}_\infty$ on $Γ^\infty_e=\{[γ_i]_{i=1}^\infty : γ_i\in Γ,\textit{only finitely many}γ_i\neq e\}$. In this paper we obtain the full description of indecomposable states $φ$ on the group $Γ\wr\mathfrak{S}_\infty,$ satisfying the condition: φ(sgs^{-1})= φ(g)\text{for each}g\in Γ\wr \mathfrak{S}_\infty,s\in\mathfrak{S}_\infty.

math.RT↗

arXiv2005

A description of characters on the infinite wreath product

Let $\mathfrak{S}_\infty$ be the infinity permutation group and $Γ$ an arbitrary group. Then $\mathfrak{S}_\infty$ admits a natural action on $Γ^\infty$ by automorphisms, so one can form a semidirect product $Γ^\infty\rtimes \mathfrak{S}_\infty$, known as the {\it wreath} product $Γ\wr\mathfrak{S}_\infty$ of $Γ$ by $\mathfrak{S}_{\infty}$. We obtain a full description of unitary $II_1-$factor-representations of $Γ\wr\mathfrak{S}_\infty$ in terms of finite characters of $Γ$. Our approach is based on extending Okounkov's classification method for admissible representations of $\mathfrak{S}_\infty\times\mathfrak{S}_\infty$. Also, we discuss certain examples of representations of type $II_1$, where the {\it modular operator} of Tomita-Takesaki expresses naturally by the asymptotic operators, which are important in the characters-theory of infinite symmetric group.

math.RT↗