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Mostrando ítems 21-30 de 32
Ponencia
A symbolic-numeric dynamic geometry environment for the computation of equidistant curves
(2013)
A web-based system that determines point/curve and curve/curve bisectors in a dynamic geometry system in a completely automatic way is presented. The system consists of an interactive drawing canvas where the bisector is ...
Ponencia
On the nonexistence of k-reptile simplices in R3 and R4
(2013)
A d-dimensional simplex S is called a k-reptile (or a k-reptile simplex) if it can be tiled without overlaps by k simplices with disjoint interiors that are all mutually congruent and similar to S. For d=2, triangular ...
Ponencia
Drawing the double circle on a grid of minimum size
(2013)
In 1926, Jarník introduced the problem of drawing a convex n-gon with vertices having integer coordinates. He constructed such a drawing in the grid [1, c ·n 3/2]2 for some constant c > 0, and showed that this grid size ...
Ponencia
Note on the number of obtuse angles in point sets
(2013)
In 1979 Conway, Croft, Erd\H{o}s and Guy proved that every set SS of nn points in general position in the plane determines at least n3/18−O(n2) obtuse angles and also presented a special set of nn points to show the upper ...
Ponencia
Guarding the vertices of thin orthogonal polygons is NP-hard
(2013)
An orthogonal polygon of P is called “thin” if the dual graph of the partition obtained by extending all edges of P towards its interior until they hit the boundary is a tree. We show that the problem of computing a minimum ...
Ponencia
Distance domination, guarding and vertex cover for maximal outerplanar graphs
(2013)
In this paper we de ne a distance guarding concept on plane graphs and associate this concept with distance domination and distance vertex cover concepts on triangulation graphs. Furthermore, for any n-vertex maximal ...
Ponencia
Flips in combinatorial pointed pseudo-triangulations with face degree at most four
(2013)
In this paper we consider the flip operation for combinatorial pointed pseudo-triangulations where faces have size 3 or 4, so-called combinatorial 4-PPTs. We show that every combinatorial 4-PPT is stretchable to a geometric ...
Ponencia
On three parameters of invisibility graphs
(2013)
The invisibility graph I(X) of a set X ⊆ Rd is a (possibly infinite) graph whose vertices are the points of X and two vertices are connected by an edge if and only if the straight-line segment connecting the two corresponding ...
Ponencia
Empty convex polytopes in random point sets
(2013)
Given a set P of points in Rd, a convex hole (alternatively, empty convex polytope) of P is a convex polytope with vertices in P, containing no points of P in its interior. Let R be a bounded convex region in Rd. We show ...
Ponencia
Some results on open edge guarding of polygons
(2013)
This paper focuses on a variation of the Art Gallery problem that considers open edge guards. The “open” prefix means the endpoints of an edge where a guard is are not taken into account for visibility purposes. This paper ...