Constrained-Path Labellings on Graphs of Bounded Clique-Width

  • Authors:
  • Bruno Courcelle;Andrew Twigg

  • Affiliations:
  • Institut Universitaire de France and Bordeaux University, LaBRI, 351 Cours de la Liberation, 33405, Talence, France;University of Oxford, Computing Laboratory, Oxford, UK

  • Venue:
  • Theory of Computing Systems
  • Year:
  • 2010

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Abstract

Given a graph G we consider the problem of preprocessing it so that given two vertices x,y and a set X of vertices, we can efficiently report the shortest path (or just its length) between x,y that avoids X. We attach labels to vertices in such a way that this length can be determined from the labels of x,y and the vertices X. For a graph with n vertices of tree-width or clique-width k, we construct labels of size O(k 2log 2 n). The constructions extend to directed graphs. The problem is motivated by routing in networks in case of failures or of routing policies which forbid certain paths.