On Dynamic Shortest Paths Problems

  • Authors:
  • Liam Roditty;Uri Zwick

  • Affiliations:
  • Bar-Ilan University, Dept. of Computer Science, 52900, Ramat-Gan, Israel;Tel-Aviv University, School of Computer Science, 69978, Tel-Aviv, Israel

  • Venue:
  • Algorithmica
  • Year:
  • 2011

Quantified Score

Hi-index 0.00

Visualization

Abstract

We obtain the following results related to dynamic versions of the shortest-paths problem: Reductions that show that the incremental and decremental single-source shortest-paths problems, for weighted directed or undirected graphs, are, in a strong sense, at least as hard as the static all-pairs shortest-paths problem. We also obtain slightly weaker results for the corresponding unweighted problems. A randomized fully-dynamic algorithm for the all-pairs shortest-paths problem in directed unweighted graphs with an amortized update time of $\tilde {O}(m\sqrt{n})$ (we use $\tilde {O}$ to hide small poly-logarithmic factors) and a worst case query time is O(n3/4). A deterministic O(n2log n) time algorithm for constructing an O(log n)-spanner with O(n) edges for any weighted undirected graph on n vertices. The algorithm uses a simple algorithm for incrementally maintaining single-source shortest-paths tree up to a given distance.