Exploració per autor "Pfeifle, Julián"
Ara es mostren els items 2-21 de 26
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Basis expansions and roots of Ehrhart polynomials
Pfeifle, Julián; Beck, Matthias; Loera, Jesús de; Develin, Mike; Richard, Stanley (2004)
Article
Accés obert -
Bounding the volume of facet-empty lattice tetrahedra
Pfeifle, Julián; Duong, Han; Haase, Christian; Reznick, Bruce (2005)
Article
Accés obert -
Búsqueda de comunidades en grafos grandes mediante configuraciones implícitas de vectores
Muntés Mulero, Víctor; Padrol Sureda, Arnau; Perarnau Llobet, Guillem; Pfeifle, Julián (PUBL. UNIVERSIDAD DE ZARAGOZA, 2009)
Text en actes de congrés
Accés obertPresentamos el algoritmo OCA para buscar comunidades solapadas en grafos grandes, como por ejemplo la Wikipedia con 1,6×107 nodos y 1,8×108 aristas. OCA se basa en la búsqueda iterativa de subconjuntos localmente óptimos ... -
CÀLCUL (Examen 1r quadrimestre, 1r parcial)
Pfeifle, Julián (Universitat Politècnica de Catalunya, 2017-11-03)
Examen
Accés restringit a la comunitat UPC -
Complejos de homomorfismos y disecciones de polígonos
Pfeifle, Julián (Secretariado de Publicaciones. Universidad de Valladolid., 2006)
Comunicació de congrés
Accés obertEncontramos 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 ... -
Continuous symmetry and shape measures
Perarnau Llobet, Guillem; Pfeifle, Julián; Saludes Closa, Jordi (Centre de Recerca Matemàtica, 2010-06)
Capítol de llibre
Accés obert -
DISCRETE AND ALGORITHMIC GEOMETRY | FINAL
Pfeifle, Julián (Universitat Politècnica de Catalunya, 2019-01-10)
Examen
Accés restringit a la comunitat UPC -
Dissections, Hom-complexes and the Cayley trick
Pfeifle, Julián (2006-06-27)
Article
Accés obertWe show that certain canonical realizations of the complexes $\Hom(G,H)$ and $\Hom_+(G,H)$ of (partial) graph homomorphisms studied by Babson and Kozlov are in fact instances of the polyhedral Cayley trick. For $G$~a ... -
Exploiting symmetry on the Universal Polytope
Pfeifle, Julián (2012)
Text en actes de congrés
Accés restringit per política de l'editorialThe most successful method to date for finding lower bounds on the number of simplices needed to triangulate a given polytope P involves optimizing a linear functional over the associated Universal Polytope U(P). However, ... -
Gale duality bounds on the location of roots of polynomials with nonnegative coefficients
Pfeifle, Julián (2010-04)
Article
Accés obertWe bound the location of roots of polynomials that have nonnegative coefficients with respect to a fixed but arbitrary basis of the vector space of polynomials of degree at most d. For this, we interpret the basis polynomials ... -
GEOMETRIA DISCRETA I ALGORÍTMICA | FINAL
Silveira, Rodrigo Ignacio; Huemer, Clemens; Pfeifle, Julián (Universitat Politècnica de Catalunya, 2023-12-19)
Examen
Accés restringit a la comunitat UPC -
Graph operations and Laplacian eigenpolytopes
Padrol Sureda, Arnau; Pfeifle, Julián (2010-07)
Text en actes de congrés
Accés obertWe introduce the Laplacian eigenpolytopes ("L-polytopes") associated to a simple undirected graph G, investigate how they change under basic operations such as taking the union, join, complement, line graph and cartesian ... -
Kalai's squeezed 3-spheres are polytopal
Pfeifle, Julián (2002)
Article
Accés obertIn 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
Accés obertIn 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 ... -
Large final polynomials from integer programming
Pfeifle, Julián (2021-09)
Article
Accés obertWe introduce a new method for finding a non-realizability certificate of a simplicial sphere S. It enables us to prove for the first time the non-realizability of a balanced 2-neighborly 3-sphere by Zheng, a family of ... -
MÈTODES MATEMÀTICS III (Examen 1r quadrimestre, 2n parcial)
Pfeifle, Julián (Universitat Politècnica de Catalunya, 2016-01-11)
Examen
Accés restringit a la comunitat UPC -
On polytopality of Cartesian products of graphs
Pfeifle, Julián; Pilaud, Vincent; Santos Pérez, Francisco Javier (2010-07)
Text en actes de congrés
Accés obertWe study the polytopality of Cartesian products of non-polytopal graphs. On the one hand, we prove that a product of graphs is the graph of a simple polytope if and only if its factors are. On the other hand, we provide ... -
On the monotone upper bound problem
Pfeifle, Julián; Ziegler, Günter M. (2004)
Article
Accés obertThe Monotone Upper Bound Problem asks for the maximal number M(d,n) of vertices on a strictly-increasing edge-path on a simple d-polytope with n facets. More specifically, it asks whether the upper bound M(d,n) ≤ ... -
Overlapping community search for social networks
Padrol Sureda, Arnau; Perarnau Llobet, Guillem; Pfeifle, Julián; Muntés Mulero, Víctor (IEEE Press. Institute of Electrical and Electronics Engineers, 2010)
Text en actes de congrés
Accés obertFinding decompositions of a graph into a family of clusters is crucial to understanding its underlying structure. While most existing approaches focus on partitioning the nodes, real-world datasets suggest the presence ... -
Polygons as sections of higher-dimensional polytopes
Padrol Sureda, Arnau; Pfeifle, Julián (2015-02-09)
Article
Accés obertWe show that every heptagon is a section of a 3-polytope with 6 vertices. This implies that every n-gon with n >= 7 can be obtained as a section of a (2 + [n/7])-dimensional polytope with at most [6n/7] vertices; and ...