English

Relative solidity results and their applications to computations of some II$_1$ factor invariants

Operator Algebras 2025-09-25 v1

Abstract

In this paper we prove that whenever GG is hyperbolic relative to a family of exact, ressidually finite subgroups {H1,,Hn}\{H_1, \ldots, H_n\}, the corresponding von Neumann algebra L(G)\mathcal L(G) is solid relative to the family of subalgebras {L(H1),,L(Hn)}\{\mathcal L(H_1),\ldots ,\mathcal L(H_n)\}. Building on this result and combining it with findings from geometric group theory, we construct a continuum of icc property (T) relative hyperbolic groups that give rise to pairwise non virtually isomorphic factors, each of which has trivial one-sided fundamental semigroup.

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Cite

@article{arxiv.2509.19481,
  title  = {Relative solidity results and their applications to computations of some II$_1$ factor invariants},
  author = {Juan Felipe Ariza Mejia and Dulanji Nikethani Amaraweera and Ionut Chifan and Krishnendu Khan},
  journal= {arXiv preprint arXiv:2509.19481},
  year   = {2025}
}

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45 Pages