# No Uncountable Polish Group Can be a Right-Angled Artin Group

**Authors:** Gianluca Paolini, Saharon Shelah

arXiv: 1701.03021 · 2017-04-04

## TL;DR

This paper demonstrates that uncountable Polish groups cannot have a generator system with a length function satisfying specific properties, implying such groups cannot be automorphism groups of uncountable structures, extending previous results.

## Contribution

It proves that uncountable Polish groups cannot be right-angled Artin groups, generalizing earlier results for free and free Abelian groups.

## Key findings

- Uncountable Polish groups cannot admit certain length functions.
- Automorphism groups of countable structures are not uncountable right-angled Artin groups.
- Extends previous results from free and free Abelian groups.

## Abstract

We prove that no uncountable Polish group can admit a system of generators whose associated length function satisfies the following conditions: (i) if $0 < k < \omega$, then $lg(x) \leq lg(x^k)$; (ii) if $lg(y) < k < \omega$ and $x^k = y$, then $x = e$. In particular, the automorphism group of a countable structure cannot be an uncountable right-angled Artin group. This generalizes results from [3] and [5], where this is proved for free and free Abelian uncountable groups.

## Full text

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## References

5 references — full list in the complete paper: https://tomesphere.com/paper/1701.03021/full.md

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Source: https://tomesphere.com/paper/1701.03021