On approximate distance labels and routing schemes with affine stretch

  • Authors:
  • Ittai Abraham;Cyril Gavoille

  • Affiliations:
  • Microsoft Research, Silicon Valley Center;Université de Bordeaux, LaBRI, France

  • Venue:
  • DISC'11 Proceedings of the 25th international conference on Distributed computing
  • Year:
  • 2011

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Abstract

For every integral parameter k 1, given an unweighted graph G, we construct in polynomial time, for each vertex u, a distance label L(u) of size Õ(n2/(2k-1)). For any u, v ε G, given L(u), L(v) we can return in time O(k) an affine approximation d(u, v) on the distance d(u, v) between u and v in G such that d(u, v) ≤ d(u, v) ≤ (2k - 2)d(u, v) + 1. Hence we say that our distance label scheme has affine stretch of (2k - 2)d + 1. For k = 2 our construction is comparable to the O(n5/3) size, 2d + 1 affine stretch of the distance oracle of Pătrascu and Roditty (FOCS '10), it incurs a o(log n) storage overhead while providing the benefits of a distance label. For any k 1, given a restriction of o(n1+1/(k-1)) on the total size of the data structure, our construction provides distance labels with affine stretch of (2k - 2)d+1 which is better than the stretch (2k - 1)d scheme of Thorup and Zwick (J. ACM '05). Our second contribution is a compact routing scheme with poly-logarithmic addresses that provides affine stretch guarantees. With Õ(n3/(3k-2))-bit routing tables we obtain affine stretch of (4k - 6)d+1, for any k 1. Given a restriction of o(n1/(k-1)) on the table size, our routing scheme provides affine stretch which is better than the stretch (4k - 5)d routing scheme of Thorup and Zwick (SPAA '01).