The complexity of the locally connected spanning tree problem

  • Authors:
  • Leizhen Cai

  • Affiliations:
  • Department of Computer Science and Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, People's Republic of China

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2003

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Abstract

A locally connected spanning tree T of a graph G is a spanning tree of G with the following property: for every vertex, its neighbourhood in T induces a connected subgraph in G. The existence of such a spanning tree in a network ensures, in case of site and line failures, effective communication amongst operative sites as long as these failures are isolated. We prove that the problem of determining whether a graph contains a locally connected spanning tree is NP-complete, even when input graphs are restricted to planar graphs or split graphs. On the other hand, we obtain a linear-time algorithm for finding a locally connected spanning tree in a directed path graph, and a linear-time algorithm for adding fewest edges to a graph to make a given spanning tree of the graph a locally connected spanning tree of the augmented graph.