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We study finite subgroups of outer automorphisms of free products. We give upper bounds for the orders of these finite subgroups as well as bounds for the orders of individual torsion outer automorphisms under some (necessary) conditions…

Group Theory · Mathematics 2025-06-23 Ioannis Papavasileiou , Dionysios Syrigos

We apply the free product construction to various local algebras in algebraic quantum field theory. If we take the free product of infinitely many identical half-sided modular inclusions with ergodic canonical endomorphism, we obtain a…

Mathematical Physics · Physics 2017-06-20 Roberto Longo , Yoh Tanimoto , Yoshimichi Ueda

The classic knapsack and related problems have natural generalizations to arbitrary (non-commutative) groups, collectively called knapsack-type problems in groups. We study the effect of free and direct products on their time complexity. We…

Group Theory · Mathematics 2015-08-11 Elizaveta Frenkel , Andrey Nikolaev , Alexander Ushakov

We study direct products of free-abelian and free groups with special emphasis on algorithmic problems. After giving natural extensions of standard notions into that family, we find an explicit expression for an arbitrary endomorphism of…

Group Theory · Mathematics 2013-01-14 J. Delgado , E. Ventura

We present examples of closed subsets of a free group such that their product is not closed in the profinite topology. We discuss how to characterize a subset of a free group which is closed in the profinite topology and its product with…

Group Theory · Mathematics 2019-06-19 Rita Gitik , Eliyahu Rips

Let V(KG) be the normalized group of units of the group ring KG of a non-Dedekind group G with nontrivial torsion part t(G) over the integral domain K. We give a simple method for constructing free objects in V(KG).In particular, we show…

Group Theory · Mathematics 2014-11-27 Victor Bovdi

Using dynamical techniques we show that there are no isolated elements on the space of left-preorders on a free product of two groups. As a consequence, when the groups are finitely generated, this space is either empty or a Cantor set. For…

Group Theory · Mathematics 2025-07-18 Iván Chércoles Cuesta

In this paper, we study the residual solvability of the generalized free product of solvable groups.

Group Theory · Mathematics 2011-03-23 Delaram Kahrobaei , Stephen Majewicz

We describe the endomorphisms of the direct product of two free groups of finite rank and obtain conditions for which the subgroup of fixed points is finitely generated and we do the same for periodic points. We also describe the…

Group Theory · Mathematics 2022-06-29 André Carvalho

In this paper, we consider the relation between the group freeness and the amalgamated freeness of crossed product algebras.

Operator Algebras · Mathematics 2007-05-23 Ilwoo Cho

In this note, we first work out some `bare hands' computations of the most elementary possible free products involving $\mathbb{C}^2 ~(=\mathbb{C} \oplus \mathbb{C} $) and $M_2 ~(= M_2(\mathbb{C}))$. Using these, we identify all free…

Operator Algebras · Mathematics 2011-11-29 Madhushree Basu

We propose a general conjecture on decompositions of finite simple groups as products of conjugates of an arbitrary subset. We prove this conjecture for bounded subsets of arbitrary finite simple groups, and for large subsets of groups of…

Group Theory · Mathematics 2014-02-26 Martin Liebeck , Nikolay Nikolov , Aner Shalev

We investigate free product structures in R. Thompson's group V, primarily by studying the topological dynamics associated with V's action on the Cantor Set. We show that the class of free products which can be embedded into V includes the…

Group Theory · Mathematics 2009-11-06 Collin Bleak , Olga Salazar-Diaz

Free products of semisimple tesnor categories are constructed with the help of polygonal presentation. The semisimplicity criterion is obtained for the Bisch-Jones' planar algebras as a byproduct.

Category Theory · Mathematics 2007-05-23 Shigeru Yamagami

The free product of an arbitrary pair of finite hyperfinite von Neumann algebras is examined, and the result is determined to be the direct sum of a finite dimensional algebra and an interpolated free group factor $L(\freeF_r)$. The finite…

funct-an · Mathematics 2008-02-03 Ken Dykema

We classify the finite groups $G$ such that the group of units of the integral group ring ${\mathbb Z} G$ has a subgroup of finite index which is a direct product of free-by-free groups.

Group Theory · Mathematics 2007-05-23 Eric Jespers , Antonio Pita , Angel del Rio , Manuel Ruiz , Pavel Zalesski

It is shown that a nontrivial normal subgroup $N$ of a group $G$ is a free factor of the $N$'s normal closure in the $G$'s free product with arbitrary nontrivial groups.

Group Theory · Mathematics 2024-01-09 Dali Zangurashvili

The category of crossed complexes gives an algebraic model of the category of $CW$-complexes and cellular maps. We explain basic results on crossed complexes which allow the computation of free crossed resolutions of graph products of…

Algebraic Topology · Mathematics 2007-05-23 Ronald Brown , Manuel Bullejos , Timothy Porter

We define a free product of connected simple graphs that is equivalent to several existing definitions when the graphs are vertex-transitive but differs otherwise. The new definition is designed for the automorphism group of the free…

Group Theory · Mathematics 2021-09-30 Max Carter , Stephan Tornier , George A. Willis

Subgroups of direct products of finitely many finitely generated free groups form a natural class that plays an important role in geometric group theory. Its members include fundamental examples, such as the Stallings-Bieri groups. This…