A note on labeling schemes for graph connectivity

  • Authors:
  • Rani Izsak;Zeev Nutov

  • Affiliations:
  • The Open University of Israel, Israel;The Open University of Israel, Israel

  • Venue:
  • Information Processing Letters
  • Year:
  • 2012

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Abstract

Let G=(V,E) be an undirected graph and let S@?V. The S-connectivity @l"G^S(u,v) of u,v@?V is the maximum number of uv-paths that no two of them have an edge or a node in S@?{u,v} in common. Edge-connectivity is the case S=@A and node-connectivity is the case S=V. Given an integer k and a subset T@?V of terminals, we consider the problem of assigning small ''labels'' (binary strings) to the terminals, such that given the labels of two terminals u,v@?T, one can decide whether @l"G^S(u,v)=k (k-partial labeling scheme) or to return min{@l"G^S(u,v),k} (k-full labeling scheme). We observe that the best known labeling schemes for edge-connectivity (the case S=@A) extend to element-connectivity (the case S@?V@?T), and use it to obtain a simple k-full labeling scheme for node-connectivity (the case S=V). If q distinct queries are expected, our k-full scheme has max-label size O(klog^2|T|logq), with success probability 1-1q for all queries. We also give a deterministic k-full labeling scheme with max-label size O(klog^3|T|). Recently, Hsu and Lu (2009) [6] gave an optimal O(klog|T|) labeling scheme for the k-partial case. This implies an O(k^2log|T|) labeling scheme for the k-full case. Our deterministic k-full labeling scheme is better for k=@W(log^2|T|).