Stackability for finitely presented groups consists of a dynamical system that iteratively moves paths into a maximal tree in the Cayley graph. Combining with formal language theoretic restrictions yields auto- or algorithmic stackability, which implies solvability of theword problem. In this paperwe give two newcharacterizations of the stackable property for groups, and use these to show that every HNN extension of a stackable group over finitely generated subgroups is stackable. We apply this to exhibit a wide range of Dehn functions that are admitted by stackable and autostackable groups, as well as an example of a stackable group with unsolvable word problem. We use similarmethods to show that there exist finitely presented metabelian groups that are non-constructible but admit an autostackable structure.
Classification :
20-XX, 68-XX
Mots-clés :
HNN extension, algorithms in groups theory, Dehn function
Affiliations des auteurs :
Susan Hermiller 
1
;
Conchita Martínez-Pérez 
2
1
University of Nebraska, Lincoln, USA
2
Universidad de Zaragoza, Spain
Susan Hermiller; Conchita Martínez-Pérez. HNN extensions and stackable groups. Groups, geometry, and dynamics, Tome 12 (2018) no. 3, pp. 1123-1158. doi: 10.4171/ggd/467
@article{10_4171_ggd_467,
author = {Susan Hermiller and Conchita Mart{\'\i}nez-P\'erez},
title = {HNN extensions and stackable groups},
journal = {Groups, geometry, and dynamics},
pages = {1123--1158},
year = {2018},
volume = {12},
number = {3},
doi = {10.4171/ggd/467},
url = {http://geodesic.mathdoc.fr/articles/10.4171/ggd/467/}
}
TY - JOUR
AU - Susan Hermiller
AU - Conchita Martínez-Pérez
TI - HNN extensions and stackable groups
JO - Groups, geometry, and dynamics
PY - 2018
SP - 1123
EP - 1158
VL - 12
IS - 3
UR - http://geodesic.mathdoc.fr/articles/10.4171/ggd/467/
DO - 10.4171/ggd/467
ID - 10_4171_ggd_467
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%U http://geodesic.mathdoc.fr/articles/10.4171/ggd/467/
%R 10.4171/ggd/467
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