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We give an explicit description of the free objects in the quasivariety of adequate semigroups, as sets of labelled directed trees under a natural combinatorial multiplication. The morphisms of the free adequate semigroup onto the free…

Rings and Algebras · Mathematics 2009-05-08 Mark Kambites

We show that all finitely generated free-by-cyclic groups are conjugacy separable: if a finitely generated group $G$ surjects onto $\mathbb{Z}$ with free kernel, then for every pair of non-conjugate elements $g,h\in G$, there exists a…

Group Theory · Mathematics 2026-04-22 François Dahmani , Sam Hughes , Monika Kudlinska , Nicholas Touikan

We show that the conjugacy problem is solvable in [finitely generated free]-by-cyclic groups, by using a result of O. Maslakova that one can algorithmically find generating sets for the fixed subgroups of free group automorphisms, and one…

Group Theory · Mathematics 2007-05-23 O. Bogopolski , A. Martino , O. Maslakova , E. Ventura

A survey article that presents some recent algebraic and model-theoretic results on the automorphism groups of relatively free groups of infinite rank. The topics include topological aspects, generating sets, descripition of automorpisms…

Group Theory · Mathematics 2008-07-29 Vladimir Tolstykh

Let $G$ be the mapping torus of a polynomially growing automorphism of a finitely generated free group. We determine which epimorphisms from $G$ to $\mathbb{Z}$ have finitely generated kernel, and we compute the rank of the kernel. We thus…

Group Theory · Mathematics 2016-06-23 Christopher H. Cashen , Gilbert Levitt

We classify all subgroups of $SO(3)$ that are generated by two elements, each a rotation of finite order, about axes separated by an angle that is a rational multiple of $\pi$. In all cases we give a presentation of the subgroup. In most…

Group Theory · Mathematics 2018-07-11 Charles Radin , Lorenzo Sadun

One of the key steps in the proof of the Banach-Tarski Theorem is the introduction of a free group of rotations. First, a free group of reduced words is generated where each element of the set is represented as an ACL2 list. Then we…

Logic in Computer Science · Computer Science 2022-05-25 Jagadish Bapanapally , Ruben Gamboa

We prove that three automorphisms of the rooted binary tree defined by a certain 3-state automaton generate a free non-Abelian group of rank 3.

Group Theory · Mathematics 2007-05-23 Mariya Vorobets , Yaroslav Vorobets

Solving functional equations given in \cite{nagy} for extensions of a group $A$ by a weighted Steiner loop $S$ we obtain concrete description for all loops with interesting weak associativity properties if the Steiner loop $S$ induces only…

Group Theory · Mathematics 2015-07-01 Ágota Figula , Karl Strambach

For a mixing shift of finite type, the associated automorphism group has a rich algebraic structure, and yet we have few criteria to distinguish when two such groups are isomorphic. We introduce a stabilization of the automorphism group,…

Dynamical Systems · Mathematics 2020-01-28 Yair Hartman , Bryna Kra , Scott Schmieding

This paper studies the long-standing open problem of the reduction of Steiner 3-designs admitting a block-transitive automorphism group. We prove that if G acts as a point-primitive, block-transitive automorphism group of a nontrivial…

Combinatorics · Mathematics 2024-08-28 Yunsong Gan , Weijun Liu

We study the automorphism groups of free-by-cyclic groups and show these are finitely generated in the following cases: (i) when defining automorphism has linear growth and (ii) when the rank of the underlying free group has rank at most 3.…

Group Theory · Mathematics 2022-11-10 Naomi Andrew , Armando Martino

In a previous paper [1] [MR4101040], we initiated a systematic study of semihypergroups and had a thorough discussion about some important analytic and algebraic objects associated to this class of objects. In this paper, we investigate…

Functional Analysis · Mathematics 2022-09-30 Choiti Bandyopadhyay

In this paper we study the structure of the rational cohomology groups of the IA-automorphism group $\mathrm{IA}_3$ of a free group of rank three by using combinatorial group theory and representation theory. In particular, we detect…

Group Theory · Mathematics 2021-01-19 Takao Satoh

We study automorphisms of the free associative algebra K<x,y,z> over a field K which fix the variable z. We describe the structure of the group of z-tame automorphisms and derive algorithms which recognize z-tame automorphisms and z-tame…

Rings and Algebras · Mathematics 2007-05-23 Vesselin Drensky , Jie-Tai Yu

This is a survey of recent progress in several areas of combinatorial algebra. We consider combinatorial problems about free groups, polynomial algebras, free associative and Lie algebras. Our main idea is to study automorphisms and, more…

Group Theory · Mathematics 2016-09-07 Alexander A. Mikhalev , Vladimir Shpilrain , Jie-Tai Yu

Let $F_n$ be the free group of a finite rank $n$. We study orbits $Orb_{\phi}(u)$, where $u$ is an element of the group $F_n$, under the action of an automorphism $\phi$. If an orbit like that is finite, we determine precisely what its…

Group Theory · Mathematics 2007-05-23 Alexei G. Myasnikov , Vladimir Shpilrain

We will show that every element of a finitely generated abelian group is automorphically equivalent what we will define to be a {\em representative element} in a {\em repeat-free subgroup}, and for finite abelian groups we can count the…

Group Theory · Mathematics 2011-09-12 Charles F. Rocca

Homology of the group Aut(F_n) of automorphisms of a free group on n generators is known to be independent of n in a certain stable range. Using tools from homotopy theory, we prove that in this range it agrees with homology of symmetric…

Algebraic Topology · Mathematics 2008-02-18 Soren Galatius

Many common finite p-groups admit automorphisms of order coprime to p, and when p is odd, it is reasonably difficult to find finite p-groups whose automorphism group is a p-group. Yet the goal of this paper is to prove that the automorphism…

Group Theory · Mathematics 2013-05-09 Geir T. Helleloid , Ursula Martin