Now showing items 1-14 of 14

  • Complejos de homomorfismos y disecciones de polígonos 

    Pfeifle, Julián (Secretariado de Publicaciones. Universidad de Valladolid., 2006)
    Conference lecture
    Open Access
    Encontramos realizaciones canónicas de los complejos politopales Hom(G,H)formados por homomorfismos de grafos y estudiados por Babson y Kozlov. Si G es un grafo completo, caracterizamos en qué casos cierta proyección ...
  • Coverage with k-transmitters in the presence of obstacles 

    Uehara, R.; Souvaine, D.; Sacristán Adinolfi, Vera; Morin, P.; Lubiw, A.; Iacono, J.; Ballinger, B.; Benbernou, N.; Bose, P.; Damian, M.; Demaine, E. D.; Dujmovic, Vida; Flatland, R.; Hurtado Díaz, Fernando Alfredo (Springer Verlag, 2010)
    Conference report
    Restricted access - publisher's policy
    For a fixed integer k ≥ 0, a k-transmitter is an omnidirectional wireless transmitter with an infinite broadcast range that is able to penetrate up to k “walls”, represented as line segments in the plane. We develop lower ...
  • Every large point set contains many collinear points or an empty pentagon 

    Wood, David; Por, Attila; Abel, Zachary; Ballinger, Brad; Bose, Prosenjit; Collette, Sébastien; Dujmovic, Vida; Hurtado Díaz, Fernando Alfredo; Kominers, Scott Duke; Langerman, Stefan (2011-01)
    Article
    Restricted access - publisher's policy
    We prove the following generalised empty pentagon theorem for every integer ℓ ≥ 2, every sufficiently large set of points in the plane contains ℓ collinear points or an empty pentagon. As an application, we settle the next ...
  • Geometric tree graphs of points in convex position 

    Hernando Martín, María del Carmen; Hurtado Díaz, Fernando Alfredo; Márquez Pérez, Alberto; Mora Giné, Mercè; Noy Serrano, Marcos (1997)
    Article
    Open Access
    Given a set $P$ of points in the plane, the geometric tree graph of $P$ is defined as the graph $T(P)$ whose vertices are non-crossing rectilinear spanning trees of $P$, and where two trees $T_1$ and $T_2$ are adjacent ...
  • Kalai's squeezed 3-spheres are polytopal 

    Pfeifle, Julián (2002)
    Article
    Open Access
    In 1988, Kalai [5] extended a construction of Billera and Lee to produce many triangulated(d−1)-spheres. In fact, in view of upper bounds on the number of simplicial d-polytopes by Goodman and Pollack [2, 3], he derived ...
  • Kalai's squeezed three-spheres are polytopal 

    Pfeifle, Julián (2001)
    Article
    Open Access
    In 1988, Kalai [5] extended a construction of Billera and Lee to produce many triangulated(d−1)-spheres. In fact, in view of upper bounds on the number of simplicial d-polytopes by Goodman and Pollack [2,3], he derived ...
  • Mesures de regularitat per a polígons convexos 

    Saumell Mendiola, Maria (Universitat Politècnica de Catalunya, 2008)
    Master thesis
    Open Access
    Al llarg d'aquesta memòria, hem plantejat possibles mesures de regularitat, totes elles justificades, per a un n-gon convex qualsevol que han donat lloc a problemes de geometria discreta i computacional. A més, hem estat ...
  • Mesures de regularitat per a polígons convexos 

    Chalmeta Ugas, Ramon (Universitat Politècnica de Catalunya, 2010-06-30)
    Master thesis (pre-Bologna period)
    Open Access
    L'objectiu d'aquest projecte ha estat fer un pas més i portar la teoria a la pràctica, per poder verificar les mesures descrites, comparar-les i així concloure quines mesures són més eficients per diferents tipus de polígons ...
  • On geodetic sets formed by boundary vertices 

    Cáceres González, José; Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Puertas González, María Luz; Seara Ojea, Carlos (2003)
    Article
    Open Access
    Let G be a finite simple connected graph. A vertex v is a boundary vertex of G if there exists a vertex u such that no neighbor of v is further away from u than v. We obtain a number of properties involving different types ...
  • On polygons enclosing point sets II 

    Hurtado Díaz, Fernando Alfredo; Merino, C.; Oliveros, D.; Sakai, T.; Urrutia, J.; Ventura, Inmaculada (2009-08)
    Article
    Open Access
    Let R and B be disjoint point sets such that $R\cup B$ is in general position. We say that B encloses by R if there is a simple polygon P with vertex set B such that all the elements in R belong to the interior of P. In ...
  • On the length and area spectrum of analytic convex domains 

    Martín, Pau; Ramírez Ros, Rafael; Tamarit Sariol, A. (2016-01)
    Article
    Open Access
    Area-preserving twist maps have at least two different (p, q)-periodic orbits and every (p, q)-periodic orbit has its (p, q)-periodic action for suitable couples (p, q). We establish an exponentially small upper bound for ...
  • Some structural, metric and convex properties of the boundary of a graph 

    Hernando Martín, María del Carmen; Mora Giné, Mercè; Pelayo Melero, Ignacio Manuel; Seara Ojea, Carlos (2013-04-25)
    Article
    Open Access
    Let u;v be two vertices of a connected graph G . The vertex v is said to be a boundary vertex of u if no neighbor of v is further away from u than v . The boundary of a graph is the set of all its ...
  • Two-convex polygons 

    Aichholzer, Oswin; Aurenhammer, Franz; Hurtado Díaz, Fernando Alfredo; Ramos, Pedro A.; Urrutia, J. (Université Libre de Bruxelles, 2009)
    Conference report
    Open Access
    We introduce a notion of k-convexity and explore some properties of polygons that have this property. In particular, 2-convex polygons can be recognized in O(n log n) time, and k-convex polygons can be triangulated in O(kn) time.
  • Witness gabriel graphs 

    Aronov, Boris; Dulieu, Muriel; Hurtado Díaz, Fernando Alfredo (2009)
    Conference report
    Open Access
    We consider a generalization of the Gabriel graph, the witness Gabriel graph. Given a set of vertices P and a set of witness points W in the plane, there is an edge ab between two points of P in the witness Gabriel graph ...