network discovery and verification

  • Authors:
  • Zuzana Beerliova;Felix Eberhard;Thomas Erlebach;Alexander Hall;Michael Hoffmann;Matúš Mihaľák;L. Shankar Ram

  • Affiliations:
  • Department of Computer Science, ETH Zürich;Department of Computer Science, ETH Zürich;Department of Computer Science, University of Leicester;Department of Computer Science, ETH Zürich;Department of Computer Science, University of Leicester;Department of Computer Science, University of Leicester;Department of Computer Science, ETH Zürich

  • Venue:
  • WG'05 Proceedings of the 31st international conference on Graph-Theoretic Concepts in Computer Science
  • Year:
  • 2005

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Abstract

Consider the problem of discovering (or verifying) the edges and non-edges of a network, modeled as a connected undirected graph, using a minimum number of queries. A query at a vertex v discovers (or verifies) all edges and non-edges whose endpoints have different distance from v. In the network discovery problem, the edges and non-edges are initially unknown, and the algorithm must select the next query based only on the results of previous queries. We study the problem using competitive analysis and give a randomized on-line algorithm with competitive ratio $O(\sqrt{nlogn})$ for graphs with n vertices. We also show that no deterministic algorithm can have competitive ratio better than 3. In the network verification problem, the graph is known in advance and the goal is to compute a minimum number of queries that verify all edges and non-edges. This problem has previously been studied as the problem of placing landmarks in a graph or determining the metric dimension of a graph. We show that there is no approximation algorithm for this problem with ratio o(log n) unless $\mathcal{P} = \mathcal{nP}$.