• An explicit construction for neighborly centrally symmetric polytopes 

      Pfeifle, Julián (2006-06-29)
      Article
      Accés obert
      We give an explicit construction, based on Hadamard matrices, for an infinite series of $\big\lfloor\frac12\sqrt{d}\big\rfloor$-neighborly centrally symmetric $d$-dimensional polytopes with $4d$~vertices. This ...
    • An Introduction to Polytope Theory through Ehrhart's Theorem 

      Cano Córdoba, Filip (Universitat Politècnica de Catalunya, 2019-10)
      Projecte Final de Màster Oficial
      Accés obert
      A classic introduction to polytope theory is presented, serving as the foundation to develop more advanced theoretical tools, namely the algebra of polyhedra and the use of valuations. The main theoretical objective is the ...
    • Dissections, Hom-complexes and the Cayley trick 

      Pfeifle, Julián (2006-06-27)
      Article
      Accés obert
      We 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 ...
    • Large final polynomials from integer programming 

      Pfeifle, Julián (2021-09)
      Article
      Accés obert
      We 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 ...
    • Lie Markov models with purine/pyrimidine symmetry 

      Fernández Sánchez, Jesús; Sumner, Jeremy; Jarvis, Peter; Woodhams, Michael D. (2015-03-01)
      Article
      Accés obert
      Continuous-time Markov chains are a standard tool in phylogenetic inference. If homogeneity is assumed, the chain is formulated by specifying time-independent rates of substitutions between states in the chain. In applications, ...
    • Mesures de regularitat per a polígons convexos 

      Saumell Mendiola, Maria (Universitat Politècnica de Catalunya, 2008)
      Projecte Final de Màster Oficial
      Accés obert
      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 ...
    • Positive Plücker tree certificates for non-realizability 

      Pfeifle, Julián (2022-01-24)
      Article
      Accés obert
      We introduce a new method for finding a non-realizability certificate of a simplicial sphere S: we exhibit a monomial combination of classical 3-term Pl¨ucker relations that yields a sum of products of determinants that ...
    • Showing non-realizability of spheres by distilling a tree 

      Pfeifle, Julián (2021)
      Text en actes de congrés
      Accés obert
      In [Zhe20a], Hailun Zheng constructs a combinatorial 3-sphere on 16 vertices whose graph is the complete 4-partite graph K4;4;4;4. Such a sphere seems unlikely to be realizable as the boundary complex of a 4-dimensional ...