Ara es mostren els items 21-40 de 41

• Improving shortest paths in the Delaunay triangulation ﻿

(2012)
Article
Accés obert
We study a problem about shortest paths in Delaunay triangulations. Given two nodes s, t in the Delaunay triangulation of a point set P, we look for a new point p that can be added, such that the shortest path from s to ...
• Large bichromatic point sets admit empty monochromatic 4-gons ﻿

(2009)
Text en actes de congrés
Accés obert
We consider a variation of a problem stated by Erd˝os and Szekeres in 1935 about the existence of a number fES(k) such that any set S of at least fES(k) points in general position in the plane has a subset of k points that ...
• Matching points with things ﻿

(Springer Verlag, 2010)
Text en actes de congrés
Accés restringit per política de l'editorial
Given an ordered set of points and an ordered set of geometric objects in the plane, we are interested in finding a non-crossing matching between point-object pairs. We show that when the objects we match the points to ...
• Moving rectangles ﻿

(2010)
Text en actes de congrés
Accés obert
Consider a set of n pairwise disjoint axis-parallel rectangles in the plane. We call this set the source rectangles S. The aim is to move S to a set of (pairwise disjoint) target rectangles T . A move consists in a ...
• Necklaces, convolutions, and X plus Y ﻿

(2014-06-01)
Article
Accés restringit per política de l'editorial
We give subquadratic algorithms that, given two necklaces each with n beads at arbitrary positions, compute the optimal rotation of the necklaces to best align the beads. Here alignment is measured according to the ℓ p ...
• On k-enclosing objects in a coloured point set ﻿

(2014)
Text en actes de congrés
Accés obert
We introduce the exact coloured k -enclosing object problem: given a set P of n points in R 2 , each of which has an associated colour in f 1 ;:::;t g , and a vec- tor c = ( c 1 ;:::;c t ), ...
• On polygons enclosing point sets II ﻿

(2009-08)
Article
Accés obert
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 some partitioning problems for two-colored point sets ﻿

(2009)
Text en actes de congrés
Accés obert
Let S be a two-colored set of n points in general position in the plane. We show that S admits at least 2 n 17 pairwise disjoint monochromatic triangles with vertices in S and empty of points of S. We further show ...
• On structural and graph theoretic properties of higher order Delaunay graphs ﻿

(2009-12)
Article
Accés obert
Given a set $\emph{P}$ of $\emph{n}$ points in the plane, the order-$\emph{k}$ Delaunay graph is a graph with vertex set $\emph{P}$ and an edge exists between two points p,q ∊ $\emph{P}$ when there is a circle through ...
• Order types and cross-sections of line arrangements in R^3 ﻿

(2014)
Text en actes de congrés
Accés restringit per política de l'editorial
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 ...
• Proximity graphs inside large weighted graphs ﻿

(2010)
Text en actes de congrés
Accés obert
Given a large weighted graph G = (V;E) and a subset U of V , we de¯ne several graphs with vertex set U in which two vertices are adjacent if they satisfy some prescribed proximity rule. These rules use the shortest path ...
• Some properties of higher order delaunay and gabriel graphs ﻿

(2010)
Text en actes de congrés
Accés obert
We consider two classes of higher order proximity graphs defined on a set of points in the plane, namely, the k-Delaunay graph and the k-Gabriel graph. We give bounds on the following combinatorial and geometric properties ...
• Stabbing simplices of point sets with k-flats ﻿

Text en actes de congrés
Accés obert
Let S be a set of n points inRdin general position.A set H of k-flats is called an mk-stabber of S if the relative interior of anym-simplex with vertices in S is intersected by at least one element of H. In thispaper we ...
• Terrain visibility with multiple viewpoints ﻿

(Springer, 2013)
Text en actes de congrés
Accés obert
We study the problem of visibility in polyhedral terrains in the presence of multiple viewpoints. We consider three fundamental visibility structures: the visibility map, the colored visibility map, and the Voronoi visibility ...
• The alternating path problem revisited ﻿

Text en actes de congrés
Accés obert
It is well known that, given "n" red points and "n" blue points on acircle, it is not always possible to find a plane geometric. Hamiltonian alternating path. In this work we prove that if we relax the constraint on the ...
• The rotation graph of k-ary trees is Hamiltonian ﻿

(Crete University Press, 2006)
Article
Accés restringit per política de l'editorial
In this paper we show that the graph of k-ary trees, connected by rotations, contains a Hamilton cycle. Our proof is constructive and thus provides a cyclic Gray code for k-ary trees. Furthermore, we identify a basic ...
• Two-convex polygons ﻿

(Université Libre de Bruxelles, 2009)
Text en actes de congrés
Accés obert
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.
• Universal point subsets for planar graphs ﻿

(Springer, 2012)
Text en actes de congrés
Accés obert
A set S of k points in the plane is a universal point subset for a class G of planar graphs if every graph belonging to G admits a planar straight-line drawing such that k of its vertices are represented by the points of ...
• Witness bar visibility graphs ﻿

(2013)
Text en actes de congrés
Accés obert
Bar visibility graphs were introduced in the seventies as a model for some VLSI layout problems. They have been also studied since then by the graph drawing community, and recently several generalizations and restricted ...
• Witness gabriel graphs ﻿

(2009)
Text en actes de congrés
Accés obert
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 ...