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Given a group action on a finite-dimensional CAT(0) cube complex, we give a simple criterion phrased purely in terms of cube stabilisers that ensures that the group satisfies the strong Tits alternative, provided that each vertex stabiliser…

Group Theory · Mathematics 2019-06-19 Alexandre Martin , Piotr Przytycki

We prove that if a subgroup $H$ of the automorphism group $\mathrm{Aut}(\Sigma^{\mathbb{Z}})$ of a non-trivial full shift acts on points of finite support with a free orbit, then for every finitely-generated abelian group $A$, the abstract…

Group Theory · Mathematics 2023-05-30 Ville Salo

Topological transitivity is a fundamental notion in topological dynamics and is widely regarded as a basic indicator of global dynamical complexity. For general cellular automata, topological transitivity is known to be undecidable. By…

Formal Languages and Automata Theory · Computer Science 2026-01-26 Niccolò Castronuovo , Alberto Dennunzio , Luciano Margara

We study sources of isomorphisms of additive cellular automata on finite groups (called index-group). It is shown that many isomorphisms (called regular) of automata are reducible to the isomorphisms of underlying algebraic structures (such…

Cellular Automata and Lattice Gases · Physics 2008-12-02 Valeriy Bulitko

We prove that for a suitably nice class of random substitutions, their corresponding subshifts have automorphism groups that contain an infinite simple subgroup and a copy of the automorphism group of a full shift. Hence, they are…

Dynamical Systems · Mathematics 2023-09-13 Robbert Fokkink , Dan Rust , Ville Salo

In this article we consider semigroups of transformations of cellular automata which act on a fixed shift space. In particular, we are interested in two properties of these semigroups which relate to "largeness". The first property is ID…

Dynamical Systems · Mathematics 2012-05-01 Yair Hartman

Group cellular automata are continuous, shift-commuting endomorphisms of $G^\mathbb{Z}$, where $G$ is a finite group. We provide an easy-to-check characterization of expansivity for group cellular automata on abelian groups and we prove…

Formal Languages and Automata Theory · Computer Science 2025-10-17 Niccolo' Castronuovo , Alberto Dennunzio , Luciano Margara

The Tits alternative for Out(F_n) is reduced to the case where all elements in the subgroup under consideration grow polynomially.

Geometric Topology · Mathematics 2007-05-23 Mladen Bestvina , Mark Feighn , Michael Handel

We compute an explicit representation of the (topological) automorphism group or a particular Toeplitz subshift. The automorphism group is a (non-finitely generated) subgroup of rational numbers under addition and the shift map corresponds…

Dynamical Systems · Mathematics 2014-12-02 Ville Salo

We present sufficient conditions for the triviality of the automorphism group of regular Toeplitz subshifts and give a broad class of examples from the class of $\mathcal{B}$-free subshifts satisfying them, extending [10]. On the other hand…

Dynamical Systems · Mathematics 2022-12-15 Aurelia Dymek , Stanisław Kasjan , Gerhard Keller

We study the outer automorphism group of a right-angled Artin group A_G in the case where the defining graph G is connected and triangle-free. We give an algebraic description of Out(A_G) in terms of maximal join subgraphs in G and prove…

Group Theory · Mathematics 2014-11-11 Ruth Charney , John Crisp , Karen Vogtmann

We study the automorphism group of an infinite minimal shift $(X,\sigma)$ such that the complexity difference function, $p(n+1)-p(n)$, is bounded. We give some new bounds on $\mbox{Aut}(X,\sigma)/\langle \sigma \rangle$ and also study the…

Dynamical Systems · Mathematics 2017-02-02 Ethan M. Coven , Anthony Quas , Reem Yassawi

In this paper, we study avoshifts and unishifts on $\mathbb{Z}^d$. Avoshifts are subshifts where for each convex set $C$, and each vector $v$ such that $C \cup \{\vec v\}$ is also convex, the set of valid extensions of globally valid…

Dynamical Systems · Mathematics 2025-04-16 Ville Salo

Following previous work of the second author, we establish more properties of groups of circle homeomorphisms which admit invariant laminations. In this paper, we focus on a certain type of such groups-so-called pseudo-fibered groups, and…

Geometric Topology · Mathematics 2020-02-24 Juan Alonso , Hyungryul Baik , Eric Samperton

In this article, we further explore the nature of a connection between the groups of automorphisms of full shift spaces and the groups of outer automorphisms of the Higman--Thompson groups $\{G_{n,r}\}$. We show that the quotient of the…

Group Theory · Mathematics 2021-11-02 James Belk , Collin Bleak , Peter J. Cameron , Feyishayo Olukoya

We show that on the four-symbol full shift, there is a finitely generated subgroup of the automorphism group whose action is (set-theoretically) transitive of all orders on the points of finite support, up to the necessary caveats due to…

Dynamical Systems · Mathematics 2018-03-01 Ville Salo

We give some optimal size generating sets for the group generated by shifts and local permutations on the binary full shift. We show that a single generator, namely the fully asynchronous application of the elementary cellular automaton 57…

Group Theory · Mathematics 2018-09-25 Ville Salo

The study of the existence of free groups in skew linear groups have been begun since the last decades of the 20-th century. The starting point is the theorem of Tits (1972), now often is referred as Tits' Alternative, stating that every…

Rings and Algebras · Mathematics 2019-02-20 Bui Xuan Hai , Huynh Viet Khanh

Many decision problems concerning cellular automata are known to be decidable in the case of algebraic cellular automata, that is, when the state set has an algebraic structure and the automaton acts as a morphism. The most studied cases…

Formal Languages and Automata Theory · Computer Science 2023-01-27 Pierre Béaur , Jarkko Kari

We show that for every integer $d$, there is a constant $N(d)$ such that if $K$ is any field and $F$ is a finite subset of $GL_d(K)$, which generates a non amenable subgroup, then $F^{N(d)}$ contains two elements, which freely generate a…

Group Theory · Mathematics 2008-04-10 Emmanuel Breuillard