Exploració per tema "Grups, Teoria de"
Ara es mostren els items 1-20 de 64
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A description of auto-fixed subgroups in a free group
(2004-06)
Article
Accés obertLet F be a finitely generated free group. By using Bestvina-Handel theory, as well as some further improvements, the eigengroups of a given automorphism of F (and its fixed subgroup among them) are globally analyzed and ... -
A recursive presentation for Mihailova's subgroup
(2010)
Article
Accés obertWe give an explicit recursive presentation for Mihailova's sub- group M(H) of Fn Fn corresponding to a nite, concise and Pei er aspherical presentation H = hx1; : : : ; xn jR1; : : : ;Rmi. This partially answers a ... -
A Whitehad algorithm for toral relatively hyperbolic groups
(2012-12-04)
Article
Accés obertThe Whitehead problem is solved in the class of toral relatively hyperbolic groups G (i.e. torsion-free relatively hyperbolic groups with abelian parabolic subgroups): there is an algorithm which, given two nite ... -
Algebraic extensions in free groups and Stallings graphs
(Universitat Politècnica de Catalunya, 2020-07)
Projecte Final de Màster Oficial
Accés obertEs realitza un estudi de les extensions algebraiques de subgrups lliures, fent ús extensiu dels grafs de Stallings, en àmbits com la sobrejectivitat de morfismes entre grafs de Stallings, o el comportament d'aquestes com ... -
Algorithmic problems for free-abelian times free groups
(2013-10-01)
Article
Accés obertWe 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 ... -
Algorithmic recognition of infinite cyclic extensions
(2016-10-25)
Article
Accés obertWe prove that one cannot algorithmically decide whether a finitely presented Z-extension admits a finitely generated base group, and we use this fact to prove the undecidability of the BNS invariant. Furthermore, we show ... -
Autòmats de Stallings, un camí d'anada i tornada
(2022-12-14)
Article
Accés obertEn aquest article revisem algunes de les propietats fonamentals del grup lliure i fem una exposició detallada de la teoria dels autòmats de Stallings, una interpretació geomètrica dels seus subgrups que ha estat (i segueix ... -
Bounding the gap between a free group (outer) automorphism and its inverse
(2016-09-01)
Article
Accés obertFor any finitely generated group GG , two complexity functions aGaG and ßGßG are defined to measure the maximal possible gap between the norm of an automorphism (respectively, outer automorphism) of GG and the norm ... -
Clasificación de 3-semigrupos numéricos mediante L-formas
(Universidad de Almería, 2012)
Text en actes de congrés
Accés restringit per política de l'editorialUn semigrupo num erico generado por tres elementos tiene asociadas una o dos teselaciones peri odicas del plano generadas por una baldosa en forma de L. Se conocen algunas propiedades combinatorias del semigrupo en t ... -
Commensurations and metric properties of Houghton's groups
(2016-12-01)
Article
Accés obertWe describe the automorphism groups and the abstract commensurators of Houghton’s groups. Then we give sharp estimates for the word metric of these groups and deduce that the commensurators embed into the corresponding ... -
Computation of numerical semigroups by means of seeds
(2018-09-01)
Article
Accés obertFor the elements of a numerical semigroup which are larger than the Frobenius number, we introduce the definition of seed by broadening the notion of generator. This new concept allows us to explore the semigroup tree in ... -
Conjugacy in houghton's groups
(2015)
Article
Accés obertLet n ∈ N. Houghton’s group Hn is the group of permutations of {1, . . . , n} × N, that eventually act as a translation in each copy of N. We prove the solvability of the conjugacy problem and conjugator search problem for ... -
Constraints on the automorphism group of a curve
(2017-01-01)
Article
Accés obertFor a curve of genus > 1 defined over a finite field, we present a sufficient criterion for the non-existence of automorphisms of order a power of a rational prime. We show how this criterion can be used to determine the ... -
Counting subgroups using Stallings automata and generalizations
(Universitat Politècnica de Catalunya, 2023-09-12)
Projecte Final de Màster Oficial
Accés obertL'estudi dels subgrups del grup lliure es pot dur a terme utilitzant la teoria desenvolupada per Stallings, que dóna una representació gràfica que codifica les propietats algebraiques d'aquests subgrups en forma d'autòmats ... -
Degree of commutativity of infinite groups
(2016-11-16)
Article
Accés obertWe prove that, in a finitely generated residually finite group of subexponential growth, the proportion of commuting pairs is positive if and only if the group is virtually abelian. In particular, this covers the case where ... -
Extensions de l'algorisme clàssic de Whitehead
(Universitat Politècnica de Catalunya, 2009-02)
Projecte Final de Màster Oficial
Accés obertL'algoritme clàssic de Whitehead decideix si dues paraules del grup lliure pertanyen o no a la mateixa òrbita per l'acció del grup d'automorfismes. La demostració clàssica és molt combinatòrica i tècnica (i desagradable ... -
Familias infinitas de digrafos de Cayley de grado 2 óptimos sobre grupos abelianos finitos
(Universidad de Almería, 2012)
Text en actes de congrés
Accés restringit per política de l'editorialSea GN un grupo abeliano finito de orden N. Para cada conjunto de generadores f, g = GN, consideremos el digrafo de Cayley Cay(GN, {f, g}). Seg´un sea GN c´ıclico o no c´ıclico, podemos obtener un di´ametro ´optimo ... -
Finite automata for Schreier graphs of virtually free groups
(2016-01-01)
Article
Accés obertThe Stallings construction for f.g. subgroups of free groups is generalized by introducing the concept of Stallings section, which allows efficient computation of the core of a Schreier graph based on edge folding. It is ... -
Fixed subgroups are compressed in surface groups
(2015-08-01)
Article
Accés obertFor a compact surface Sigma (orientable or not, and with boundary or not), we show that the fixed subgroup, Fix B, of any family B of endomorphisms of pi(1)(Sigma) is compressed in pi(1)(Sigma), i.e. rk(Fix B) <= rk(H) for ... -
Fixed subgroups in direct products of surface groups of Euclidean type
(2020-02-24)
Article
Accés obertWe give an explicit characterization of which direct products G of surface groups of Euclidean type satisfy that the fixed subgroup of any automorphism (or endomorphism) of G is compressed, and of which is it always inert.
