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- Annette Ebbers-Baumann, Ansgar Grüne, Rolf Klein
- ISAAC
- 2003

Let G be an embedded planar graph whose edges may be curves. For two arbitrary points of G, we can compare the length of the shortest path in G connecting them against their Euclidean distance. The maximum of all these ratios is called the geometric dilation of G. Given a finite point set, we would like to know the smallest possible dilation of any graph… (More)

Let P be a simple polygon in 2 with n vertices. The detour of P between two points, p, q ∈ P , is the length of a shortest path contained in P and connecting p to q, divided by the distance of these points. The detour of the whole polygon is the maximum detour between any two points in P. We first analyze properties of pairs of points with maximum detour.… (More)

- Annette Ebbers-Baumann, Ansgar Grüne, Rolf Klein
- Algorithmica
- 2006

A pride of lions are prowling among the vertices and edges of an n × n grid. If their paths are known in advance, is it possible to design a safe path for a man that avoids all lions, assuming that man and lion move at the same speed? In their recent paper [4], Dumitrescu et al. employed probabilistic arguments to show that O(√ n) lions can always be… (More)

- Adrian Dumitrescu, Annette Ebbers-Baumann, Ansgar Grüne, Rolf Klein, Günter Rote
- Comput. Geom.
- 2007

Let G be an embedded planar graph whose edges are curves. The detour between two points p and q (on edges or vertices) of G is the ratio between the length of a shortest path connecting p and q in G and their Euclidean distance |pq|. The maximum detour over all pairs of points is called the geometric dilation δ(G). Ebbers-Baumann, Grüne and Klein have shown… (More)

- Florian Berger, Alexander Gilbers, Ansgar Grüne, Rolf Klein
- Algorithms
- 2009

We consider a pursuit-evasion problem where some lions have the task to clear a grid graph whose nodes are initially contaminated. The contamination spreads one step per time unit in each direction not blocked by a lion. A vertex is cleared from its contamination whenever a lion moves to it. Brass et al. [5] showed that n 2 lions are not enough to clear the… (More)

- Annette Ebbers-Baumann, Ansgar Grüne, Rolf Klein
- Comput. Geom.
- 2007

Given two points on a closed planar curve, C, we can divide the length of a shortest connecting path in C by their Euclidean distance. The supremum of these ratios, taken over all pairs of points on the curve, is called the geometric dilation of C. We provide lower bounds for the dilation of closed curves in terms of their geometric properties, and prove… (More)

- Annette Ebbers-Baumann, Ansgar Grüne, Rolf Klein, Marek Karpinski, Christian Knauer, Andrzej Lingas
- Int. J. Comput. Geometry Appl.
- 2005

Let S be a set of points in the plane. What is the minimum possible dilation of all plane graphs that contain S? Even for a set S as simple as five points evenly placed on the circle, this question seems hard to answer; it is not even clear if there exists a lower bound > 1. In this paper we provide the first upper and lower bounds for the embedding… (More)

Let G be an embedded planar graph whose edges may be curves. The detour between two points, p and q (on edges or vertices) of G, is the ratio between the shortest path in G between p and q and their Euclidean distance. The supremum over all pairs of points of all these ratios is called the geometric dilation of G. Our research is motivated by the problem of… (More)

Let G be an embedded planar graph whose edges are curves. The detour between two points u and v (on edges or vertices) of G is the ratio between the shortest path in G between u and v and their Euclidean distance. The maximum detour over all pairs of points is called the geometric dilation δ(G). Ebbers-Baumann, Grüne and Klein have recently shown that every… (More)