The Identity Problem in virtually solvable matrix groups over algebraic numbers

Fuente: arXiv
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Hauptverfasser: Bodart, Corentin, Dong, Ruiwen
Format: Preprint
Veröffentlicht: 2024
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author Bodart, Corentin
Dong, Ruiwen
author_facet Bodart, Corentin
Dong, Ruiwen
contents The Tits alternative states that a finitely generated matrix group either contains a nonabelian free subgroup $F_2$, or it is virtually solvable. This paper considers two decision problems in virtually solvable matrix groups: the Identity Problem (does a given finitely generated subsemigroup contain the identity matrix?), and the Group Problem (is a given finitely generated subsemigroup a group?). We show that both problems are decidable in virtually solvable matrix groups over the field of algebraic numbers $\overline{\mathbb{Q}}$. Our proof also extends the decidability result for nilpotent groups by Bodart, Ciobanu, Metcalfe and Shaffrir, and the decidability result for metabelian groups by Dong (STOC'24). Since the Identity Problem and the Group Problem are known to be undecidable in matrix groups containing $F_2 \times F_2$, our result significantly reduces the decidability gap for both decision problems.
format Preprint
id arxiv_https___arxiv_org_abs_2404_02264
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The Identity Problem in virtually solvable matrix groups over algebraic numbers
Bodart, Corentin
Dong, Ruiwen
Group Theory
Discrete Mathematics
Formal Languages and Automata Theory
Algebraic Geometry
The Tits alternative states that a finitely generated matrix group either contains a nonabelian free subgroup $F_2$, or it is virtually solvable. This paper considers two decision problems in virtually solvable matrix groups: the Identity Problem (does a given finitely generated subsemigroup contain the identity matrix?), and the Group Problem (is a given finitely generated subsemigroup a group?). We show that both problems are decidable in virtually solvable matrix groups over the field of algebraic numbers $\overline{\mathbb{Q}}$. Our proof also extends the decidability result for nilpotent groups by Bodart, Ciobanu, Metcalfe and Shaffrir, and the decidability result for metabelian groups by Dong (STOC'24). Since the Identity Problem and the Group Problem are known to be undecidable in matrix groups containing $F_2 \times F_2$, our result significantly reduces the decidability gap for both decision problems.
title The Identity Problem in virtually solvable matrix groups over algebraic numbers
topic Group Theory
Discrete Mathematics
Formal Languages and Automata Theory
Algebraic Geometry
url https://arxiv.org/abs/2404.02264