Abstract
Given a graph G = (V,E), a subgraph G′ = (V,H), H ⊆ E is a k-spanner (respectively, k-DSS) of G if for any pair of vertices u,w ∈ V it satisfies d H(u,w) ≤ k · d G(u,w) (resp., d H(u,w) ≤ k). The basic k- spanner (resp., k-DSS ) problem is to find a k-spanner (resp., k-DSS) of a given graph G with the smallest possible number of edges.
This paper considers approximation algorithms for these and some related problems for k > 2. Both problems are known to be \( \Omega (2^{log^{1 - \in } n} ) - \) inapproximable [11,13]. The basic k-spanner problem over undirected graphs with k > 2 has been given a sublinear ratio approximation algorithm (with ratio roughly \( O(n^{\frac{2} {{k + 1}}} )) \) ), but no such algorithms were known for other variants of the problem, including the directed and the client- server variants, as well as for the k-DSS problem. We present the first approximation algorithms for these problems with sublinear approximation ratio.
The second contribution of this paper is in characterizing some wide families of graphs on which the problems do admit a logarithmic and a polylogarithmic approximation ratios. These families are characterized as containing graphs that have optimal or “near-optimal” spanners with certain desirable properties, such as being a tree, having low arboricity or having low girth. All our results generalize to the directed and the client-server variants of the problems. As a simple corollary, we present an algorithm that given a graph G builds a subgraph with Õ(n) edges and stretch bounded by the tree-stretch of G, namely the minimum maximal stretch of a spanning tree for G.
The analysis of our algorithms involves the novel notion of edge-dominating systems developed in the paper. The technique introduced in the paper enables us to reduce the studied algorithmic questions of approximability of the k-spanner and k-DSS problems to purely graph-theoretical questions concerning the existence of certain combinatorial objects in families of graphs.
Supported in part by grants from the Israel Science Foundation and from the Israel Ministry of Science and Art.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Baruch Awerbuch, Alan Baratz, and David Peleg. Efficient broadcast and lightweightspanners. Unpublished manuscript, November 1991.
I. Althöfer, G. Das, D. Dobkin, and D. Joseph, Generating sparse spanners forweighted graphs, Proc. 2nd Scnadinavian Workshop on Algorithm Theory, Lect. Notes in Comput. Sci., Vol. 447, pp. 26–37, Springer-Verlag, New York/Berlin, 1990.
B. Bollobas, Extremal Graph Theory, Academic Press, New York, 1978.
L.P. Chew, There is a planar graph almost as good as the complete graph, Proc.ACM Symp. on Computational Geometry, 1986, pp. 169–177
L. Cai, NP-completeness of minimum spanner problems. Discrete Applied Math., 48:187–194, 1994
L. Cai and D.G. Corneil, Tree Spanners, SIAM J. on Discrete Mathematics 8, (1995), 359–387.
B. Chandra, G. Das, G. Narasimhan, J. Soares, New Sparseness Results on Graph Spanners, Proc. 8th ACM Symp. on Computational Geometry, pp. 192–201, 1992.
D.P. Dobkin, S.J. Friedman and K.J. Supowit, Delaunay graphs are almost as goodas complete graphs, Proc. 31st IEEE Symp. on Foundations of Computer Science, 1987, pp. 20–26.
D. Dor, S. Halperin, U. Zwick, All pairs almost shortest paths, Proc. 37th IEEE Symp. on Foundations of Computer Science, 1997, pp. 452–461.
M.-L. Elkin and D. Peleg, The Hardness of Approximating Spanner Problems, Proc. 17th Symp. on Theoretical Aspects of Computer Science, Lille, France, Feb. 2000, 370–381.
M.-L. Elkin and D. Peleg, Strong Inapproximability of the Basic k-Spanner Problem, Proc. 27th International Colloquim on Automata, Languages and Programming, Geneva, Switzerland, July 2000. See also Technical Report MCS99-23, the Weizmann Institute of Science, 1999.
M.-L. Elkin and D. Peleg, The Client-Server 2-Spanner Problem and Applications to Network Design, Technical Report MCS99-24, the Weizmann Institute of Science, 1999.
M.-L. Elkin, Additive Spanners and Diameter Problem, manuscript, 2000.
M.-L. E lkin and D. Peleg, Spanners with Stretch 1 + ∈ and Almost Linear Size, manuscript, 2000.
S. P. Fekete, J. Kremer, Tree Spanners in Planar Graphs, Angewandte Mathematikund Informatik Universitat zu Koln, Report No. 97.296
S. Halperin, U. Zwick, Private communication, 1996.
G. Kortsarz, On the Hardness of Approximating Spanners, Proc. 1st Int. Workshop on Approximation Algorithms for Combinatorial Optimization Problems, Lect. Notes in Comput. Sci., Vol. 1444, pp. 135–146, Springer-Verlag, New York/Berlin, 1998.
G. Kortsarz and D. Peleg, Generating Sparse 2-Spanners. J. Algorithms, 17 (1994) 222–236.
E.L. Lawler, Combinatorial Optimization: Networks and Matroids, Holt, Rinehart,Winston, New York, 1976.
D. Peleg, Distributed Computing: A Locality-Sensitive Approach, SIAM, Philadelphia,PA, 2000.
D. Peleg and A. Schäer, Graph Spanners, J. Graph Theory 13 (1989), 99–116.
D. Peleg and E. Reshef, A Variant of the Arrow Distributed Directory with Low Average Complexity, Proc. 26th Int. Colloq. on Automata, Languages amp; Prog., Prague, Czech Republic, July 1999, 615–624.
D. Peleg and J.D. Ullman, An optimal synchronizer for the hypercube, SIAM J. Computing 18 (1989), pp. 740–747.
E. Scheinerman, The maximal integer number of graphs with given genus, J. GraphTheory 11 (1987), no. 3, 441–446.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2001 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Elkin, M., Peleg, D. (2001). Approximating k-Spanner Problems for k > 2. In: Aardal, K., Gerards, B. (eds) Integer Programming and Combinatorial Optimization. IPCO 2001. Lecture Notes in Computer Science, vol 2081. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-45535-3_8
Download citation
DOI: https://doi.org/10.1007/3-540-45535-3_8
Published:
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-540-42225-9
Online ISBN: 978-3-540-45535-6
eBook Packages: Springer Book Archive