An Optimal Minimum Spanning Tree Algorithm

  • Authors:
  • Seth Pettie;Vijaya Ramachandran

  • Affiliations:
  • -;-

  • Venue:
  • ICALP '00 Proceedings of the 27th International Colloquium on Automata, Languages and Programming
  • Year:
  • 2000

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Abstract

We establish that the algorithmic complexity of the minimum spanning tree problem is equal to its decision-tree complexity. Specifically, we present a deterministic algorithm to find a minimum spanning forest of a graph with n vertices and m edges that runs in time O(Τ*(m, n)) where Τ* is the minimum number of edge-weight comparisons needed to determine the solution. the algorithm is quite simple and can be implemented on a pointer machine. Although our time bound is optimal, the exact function describing it is not known at present. the current best bounds known for Τ* are Τ*(m, n) = Ω(m) and Τ*(m, n) = O(m ċ α(m, n)), where α is a certain natural inverse of Ackermann's function. Even under the assumption that Τ* is super-linear, we show that if the input graph is selected from Gn,m, our algorithm runs in linear time w.h.p., regardless of n, m, or the permutation of edge weights. the analysis uses a new martingale for Gn,m similar to the edge-exposure martingale for Gn,p.