Enviaments recents

  • Commensurations and metric properties of Houghton's groups 

    Burillo Puig, José; Cleary, Sean; Martino, Armando; Röver, Claas E. (2016-12-01)
    Article
    Accés obert
    We 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 ...
  • Layer structure of De Bruijn and Kautz digraphs: an application to deflection routing 

    Fàbrega Canudas, José; Martí Farré, Jaume; Muñoz López, Francisco Javier (2016-10-17)
    Article
    Accés restringit per política de l'editorial
    In the main part of this paper we present polynomial expressions for the cardinalities of some sets of interest of the nice distance-layer structure of the well-known De Bruijn and Kautz digraphs. More precisely, given a ...
  • The conjugacy problem in extensions of Thompson's group F 

    Burillo Puig, José; Matucci, Francesco; Ventura Capell, Enric (2016-10-01)
    Article
    Accés restringit per política de l'editorial
    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 ...
  • Correlation among runners and some results on the lonely runner conjecture 

    Perarnau, Guillem; Serra Albó, Oriol (2016-10-03)
    Article
    Accés obert
    The Lonely Runner Conjecture, posed independently by Wills and by Cusick, states that for any set of runners running along the unit circle with constant different speeds and starting at the same point, there is a time where ...
  • Rainbow perfect matchings in r-partite graph structures 

    Cano Vila, María del Pilar; Perarnau, Guillem; Serra Albó, Oriol (2016-10-03)
    Article
    Accés restringit per política de l'editorial
    A matching M in an edge–colored (hyper)graph is rainbow if each pair of edges in M have distinct colors. We extend the result of Erdos and Spencer on the existence of rainbow perfect matchings in the complete bipartite ...
  • A geometric approach to dense Cayley digraphs of finite Abelian groups 

    Aguiló Gost, Francisco de Asis L.; Fiol Mora, Miquel Àngel; Pérez Mansilla, Sonia (2016)
    Article
    Accés restringit per política de l'editorial
    We give a method for constructing infinite families of dense (or eventually likely dense) Cayley digraphs of finite Abelian groups. The diameter of the digraphs is obtained by means of the related minimum distance diagrams. ...
  • Perspectivas en combinatoria 

    Noy Serrano, Marcos; Serra Albó, Oriol (Real Sociedad Matemática Española, 2016-10-03)
    Article
    Accés obert
  • Some spectral and quasi-spectral characterizations of distance-regular graphs 

    Abiad, Aida; Van Dam, Edwin R; Fiol Mora, Miquel Àngel (2016-10-01)
    Article
    Accés restringit per política de l'editorial
    In this paper we consider the concept of preintersection numbers of a graph. These numbers are determined by the spectrum of the adjacency matrix of the graph, and generalize the intersection numbers of a distance-regular ...
  • The spectral excess theorem for distance-regular graphs having distance-d graph with fewer distinct eigenvalues 

    Fiol Mora, Miquel Àngel (2016-06-01)
    Article
    Accés restringit per política de l'editorial
    Let Gamma be a distance-regular graph with diameter d and Kneser graph K = Gamma(d), the distance-d graph of Gamma. We say that Gamma is partially antipodal when K has fewer distinct eigenvalues than Gamma. In particular, ...
  • Symmetry breaking in tournaments 

    Lozano Bojados, Antoni (2013-03-24)
    Article
    Accés obert
    We provide upper bounds for the determining number and the metric dimension of tournaments. A set of vertices S in V(T) is a determining set for a tournament T if every nontrivial automorphism of T moves at least one vertex ...

Mostra'n més