Ara es mostren els items 57-72 de 72

    • On automorphism-fixed subgroups of a free group 

      Martino, Armando; Ventura Capell, Enric (2000-08)
      Article
      Accés obert
      Let F be a flnitely generated free group, and let n denote its rank. A subgroup H of F is said to be automorphism-flxed, or auto-flxed for short, if there exists a set S of automorphisms of F such that H is precisely the ...
    • On endomorphisms of torsion-free hyperbolic groups 

      Bogopolski, Oleg; Ventura Capell, Enric (2011-02-10)
      Article
      Accés obert
    • On two distributions of subgroups of free groups 

      Bassino, Frédérique; Martino, Armando; Nicaud, Cyril; Ventura Capell, Enric; Weil, Pascal (Society for Industrial and Applied Mathematics, 2010)
      Text en actes de congrés
      Accés restringit per política de l'editorial
      We study and compare two natural distributions of finitely generated subgroups of free groups. One is based on the random generation of tuples of reduced words; that is the one classically used by group theorists. The ...
    • Onto extensions of free groups 

      Ventura Capell, Enric; Mijares, Sebastià (2021-04-07)
      Article
      Accés obert
      Rationale Cocaine addiction is a chronic relapsing disorder that lacks of an effective treatment. Isoflavones are a family of compounds present in different plants and vegetables like soybeans that share a common chemical ...
    • Probabilistic nilpotence in infinite groups 

      Ventura Capell, Enric; Martino, Armando; Tointon, Matthew C.H.; Valiunas, Motiejus (2021-07-02)
      Article
      Accés obert
      The ‘degree of k-step nilpotence’ of a finite group G is the proportion of the tuples (x1,…, xk+1 ¿ Gk+1 for which the simple commutator [x1, …, xk+1] is equal to the identity. In this paper we study versions of this for ...
    • Relative order and spectrum in free and related groups 

      Delgado Rodríguez, Jordi; Ventura Capell, Enric; Zakharov, Alexander (2022-12-19)
      Article
      Accés obert
      We consider a natural generalization of the concept of order of an element in a group: an element g ¿ G is said to have order k in a subgroup H (resp., in a coset Hu) of a group G if k is the first strictly positive integer ...
    • Stallings automata and applications : BGSMath graduate course 

      Delgado Rodríguez, Jordi; Ventura Capell, Enric; Weil, Pascal (2023-02-15)
      Report de recerca
      Accés obert
      The theory of Stallings automata provides a neat geometric representation of subgroups of the free group, and constitutes the modern —and probably the most natural and fruitful — approach to their study. Moreover, if the ...
    • Stallings automata for free-times-abelian groups: intersections and index 

      Delgado Pin, Jordi; Ventura Capell, Enric (2022-06-22)
      Article
      Accés obert
      We extend the classical Stallings theory (describing subgroups of free groups as automata) to direct products of free and abelian groups: after introducing enriched automata (i.e., automata with extra abelian labels), we ...
    • Statistical properties of subgroups of free groups 

      Bassino, Frederique; Martino, Armando; Nicaud, Cyril; Ventura Capell, Enric; Weil, Pascal (2013-02-04)
      Article
      Accés obert
      The usual way to investigate the statistical properties of finitely generated subgroups of free groups, and of finite presentations of groups, is based on the so-called word-based distribution: subgroups are generated ...
    • The automorphism group of a free-by-cyclic group in rank 2 

      Bogopolski, Oleg; Martino, Armando; Ventura Capell, Enric (2007-05)
      Article
      Accés obert
      Let ¡ be an automorphism of a free group F 2 of rank 2 and let M ¡ = F 2 o ¡ Z be the corresponding mapping torus of ¡ . We prove that the group Out ( M ¡ ) is usually virtually cyclic. More- over, ...
    • The conjugacy problem for free-by-cyclic groups 

      Martino, Armando; Ventura Capell, Enric (2004-04)
      Report de recerca
      Accés obert
      We show that the conjugacy problem is solvable in [finitely generated free]-by-cyclic groups, by using a result of O. Maslakova that one can algorithmically find generating sets for the fixed sub- groups of free group ...
    • The conjugacy problem in automaton groups is not solvable 

      Šunic, Z.; Ventura Capell, Enric (2012-08-15)
      Article
      Accés obert
      (Free abelian)-by-free, self-similar groups generated by finite self-similar sets of tree automorphisms and having unsolvable conjugacy problem are constructed. Along the way, finitely generated, orbit undecidable, free ...
    • The conjugacy problem in extensions of Thompson's group F 

      Burillo Puig, José; Matucci, Francesco; Ventura Capell, Enric (2016-10-01)
      Article
      Accés obert
      We solve the twisted conjugacy problem on Thompson’s group F. We also exhibit orbit undecidable subgroups of Aut(F), and give a proof that Aut(F) and Aut+(F) are orbit decidable provided a certain conjecture on Thompson’s ...
    • TOPOLOGIA 

      Ventura Capell, Enric (Universitat Politècnica de Catalunya, 2024-04-04)
      Examen
      Accés restringit a la comunitat UPC
    • Twisted conjugacy in braid groups 

      Gonzalez Meneses, Juan; Ventura Capell, Enric (2014-01-01)
      Article
      Accés obert
      In this note we solve the twisted conjugacy problem for braid groups, i.e., we propose an algorithm which, given two braids u,v is an element of B-n and an automorphism phi is an element of Aut(B-n), decides whether v = ...
    • Twisted conjugacy problem for endomorphisms of metabelian groups 

      Ventura Capell, Enric; Romankov, Vitali (Springer, 2009-03-01)
      Article
      Accés restringit per política de l'editorial
      Let M be a finitely generated metabelian group explicitly presented in a variety A2 of all metabelian groups. An algorithm is constructed which, for every endomorphism ϕ ∈ End(M) identical modulo an Abelian normal subgroup ...