Negative resolution to the $C^*$-algebraic Tarski problem

Fuente: arXiv
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Main Authors: Elayavalli, Srivatsav Kunnawalkam, Schafhauser, Christopher
Format: Preprint
Published: 2025
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author Elayavalli, Srivatsav Kunnawalkam
Schafhauser, Christopher
author_facet Elayavalli, Srivatsav Kunnawalkam
Schafhauser, Christopher
contents We compute the $K_1$-group of ultraproducts of unital, simple $C^*$-algebras with unique trace and strict comparison. As an application, we prove that the reduced free group $C^*$-algebras $C^*_r(F_m)$ and $C^*_r(F_n)$ are elementarily equivalent (i.e., have isomorphic ultrapowers) if and only if $m = n$. This settles in the negative the $C^*$-algebraic analogue of Tarski's 1945 problem for groups.
format Preprint
id arxiv_https___arxiv_org_abs_2503_10505
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Negative resolution to the $C^*$-algebraic Tarski problem
Elayavalli, Srivatsav Kunnawalkam
Schafhauser, Christopher
Operator Algebras
Group Theory
Logic
We compute the $K_1$-group of ultraproducts of unital, simple $C^*$-algebras with unique trace and strict comparison. As an application, we prove that the reduced free group $C^*$-algebras $C^*_r(F_m)$ and $C^*_r(F_n)$ are elementarily equivalent (i.e., have isomorphic ultrapowers) if and only if $m = n$. This settles in the negative the $C^*$-algebraic analogue of Tarski's 1945 problem for groups.
title Negative resolution to the $C^*$-algebraic Tarski problem
topic Operator Algebras
Group Theory
Logic
url https://arxiv.org/abs/2503.10505