Enric Ventura – författare

This volume features seventeen extended conference abstracts corresponding to selected talks given by participants at the CRM research program “Automorphisms of Free Groups: Algorithms, Geometry and Dynamics”, which took place at the Centre de Recerca Matemàtica in Barcelona in fall 2012. Most of them are short articles giving preliminary presentations of new results not yet published in regular research journals. The articles are the result from a direct collaboration among active researchers in the area after working in a dynamic and productive atmosphere. The book is intended for established researchers in the area of Group Theory, as well as for PhD and postdoc students who wish to learn more about the latest advances in this active area of research.

This volume features seventeen extended conference abstracts corresponding to selected talks given by participants at the CRM research program “Automorphisms of Free Groups: Algorithms, Geometry and Dynamics”, which took place at the Centre de Recerca Matemàtica in Barcelona in fall 2012. Most of them are short articles giving preliminary presentations of new results not yet published in regular research journals. The articles are the result from a direct collaboration among active researchers in the area after working in a dynamic and productive atmosphere. The book is intended for established researchers in the area of Group Theory, as well as for PhD and postdoc students who wish to learn more about the latest advances in this active area of research.

This volume presents the lecture notes from the authors’ three summer courses offered during the program “Automorphisms of Free Groups: Geometry, Topology, and Dynamics,” held at the Centre de Recerca Matemàtica (CRM) in Bellaterra, Spain. The first two chapters present the basic tools needed, from formal language theory (regular and context-free languages, automata, rewriting systems, transducers, etc) and emphasize their connections to group theory, mostly relating to free and virtually-free groups. The material covered is sufficient to present full proofs of many of the existing interesting characterizations of virtually-free groups. In turn, the last chapter comprehensively describes Bonahon’s construction of Thurston’s compactification of Teichmüller space in terms of geodesic currents on surfaces. It also includes several intriguing extensions of the notion of geodesic current to various other, more general settings.

This volume has its origins in the Barcelona Conference in Group Theory (July 2005) and the conference "Asymptotic and Probabilistic Methods in Geometric Group Theory" held in Geneva (June 2005). Twelve peer-reviewed research articles written by experts in the field present the most recent results in abstract and geometric group theory. In particular there are two articles by A. Juhasz.

The paper by O. Bogopolski and A. Vikentiev describes some particularly useful?niteindexsubgroupsoftheautomorphismgroupofa?nitelygeneratedfree group. One of their uses may be to attack the problem on the Kazhdan property (T) for these groups. The paper of A. Juhasz contains a solution of the di?cult membership problem in a subclass of one-relator groups. Papers of F. Matucci, D. Savchuk and R. Zarzycki will attract the attention of those who want to know more about groups of transformations of the unit interval [0,1], in particular about the famous Thompson's group F and its limit properties. The paper by A.J. Duncan, V. Dieckert and A.G. Myasnikov contains a very thoroughsurveyonrewritingsystemswithnewissuesonin?niterewritingsystems. The paper by L. Frenkel, A.G. Myasnikov and V.N. Remeslennikov is devoted to theproblemofhowto measuresomesubsets infreegroupsbyusingrandomwalks. The results of this paper may be used for designing algorithms that run fast on almost all inputs. This paper as well as the paper by M. Hock and B. Tsaban are highly recommended to specialists in cryptography. Finally, the paper by D. Goncalves and P.Wong is devoted to the twisted conjugacy in 2-dimensional crystallographic groups. We are very grateful to the organizations that supported these two conferences: * TheconferenceinDortmundwasorganizedbyO.Bogopolski,M.-T.Bochnig, G.Rosenberger,V.Shpilrainand E.Ventura.Thisconferencewas?nancially supported by DAAD (Deutscher Akademischer Austauschdienst), by DFG (Deutsche Forschungsgemeinschaft), and by the Universit. at Dortmund. The URL address for its homepage is http://www.mathematik.uni-dortmund.de/?gcgta/.