Title
Automorphic Orbits In Free Groups: Words Versus Subgroups
Abstract
We show that the following problems are decidable in a rank 2 free group F-2: Does a given finitely generated subgroup H contain primitive elements? And does H meet the orbit of a given word u under the action of G, the group of automorphisms of F-2? Moreover, decidability subsists if we allow H to be a rational subset of F-2, or alternatively if we restrict G to be a rational subset of the set of invertible substitutions (a.k.a. positive automorphisms). In higher rank, the following weaker problem is decidable: given a finitely generated subgroup H, a word u and an integer k, does H contain the image of u by some k-almost bounded automorphism? An automorphism is k-almost bounded if at most one of the letters has an image of length greater than k.
Year
DOI
Venue
2010
10.1142/S0218196710005790
INTERNATIONAL JOURNAL OF ALGEBRA AND COMPUTATION
Keywords
Field
DocType
Free groups, automorphisms, orbits, f.g. subgroups, stallings' automata
Stallings theorem about ends of groups,Discrete mathematics,Outer automorphism group,Free product,Combinatorics,Automorphisms of the symmetric and alternating groups,Algebra,Automorphism,Subgroup,Mathematics,Bounded function,Free group
Journal
Volume
Issue
ISSN
20
4
0218-1967
Citations 
PageRank 
References 
3
0.50
2
Authors
2
Name
Order
Citations
PageRank
Pedro V. Silva114129.42
Pascal Weil2717.01