Now showing items 1-5 of 5

    • Note on the number of obtuse angles in point sets 

      Fabila-Monroy, Ruy; Huemer, Clemens; Tramuns, Eulàlia (2014-09)
      Article
      Open Access
      In $1979$ Conway, Croft, Erd\H{o}s and Guy proved that every set $S$ of $n$ points in general position in the plane determines at least $\frac{n^3}{18}-O(n^2)$ obtuse angles and also presented a special set of $n$ points ...
    • Order types and cross-sections of line arrangements in R^3 

      Aichholzer, Oswin; Fabila-Monroy, Ruy; Hurtado Díaz, Fernando Alfredo; Pérez Lantero, Pablo; Ruiz Vargas, Andrés; Urrutia Galicia, Jorge; Vogtenhuber, Birgit (2014)
      Conference report
      Restricted access - publisher's policy
      We consider sets L = {l1,...., ln} of n labeled lines in general position in R3, and study the order types of point sets fp1; : : : ; png that stem from the intersections of the lines in L with (directed) planes II, not ...
    • Order types of random point sets can be realized with small integer coordinates 

      Fabila-Monroy, Ruy; Huemer, Clemens (2017)
      Conference report
      Open Access
      Let S := {p1, . . . , pn} be a set of n points chosen independently and uniformly at random from the unit square and let M be a positive integer. For every point pi = (xi , yi) in S, let p 0 i = (bMxic, bMyic). Let S 0 := ...
    • Ramsey numbers for empty convex polygons 

      Bautista-Santiago, Crevel; Cano, Javier; Fabila-Monroy, Ruy; Hidalgo-Toscano, Carlos; Huemer, Clemens; Leaños, Jesús; Sakai, Toshinori; Urrutia, Jorge (University of Ljubljana, 2015)
      Conference report
      Restricted access - publisher's policy
      We study a geometric Ramsey type problem where the vertices of the complete graph Kn are placed on a set S of n points in general position in the plane, and edges are drawn as straight-line segments. We define the empty ...
    • The number of empty four-gons in random point sets 

      Fabila-Monroy, Ruy; Huemer, Clemens; Mitsche, Dieter (2014)
      Article
      Open Access
      Let S be a set of n points distributed uniformly and independently in the unit square. Then the expected number of empty four-gons with vertices from S is T(n^2 log¿ n). A four-gon is empty if it contains no points of S ...