Constructing a tree from homeomorphic subtrees, with applications to computational evolutionary biology

M. R. Henzinger, V. King, T. Warnow

Research output: Contribution to journalArticle


We are given a set script T sign = {T1, T2, . . . , Tk) of rooted binary trees, each Ti leaf-labeled by a subset ℒ(Ti] ⊂ {1,2, . . . , n}. If T is a tree on {1, 2, . . . , n}, we let T\ℒ denote the minimal subtree of T induced by the nodes of ℒ and all their ancestors. The consensus tree problem asks whether there exists a tree T* such that, for every i, T*\ℒ(Ti) is homeomorphic to Ti. We present algorithms which test if a given sel of trees has a consensus tree and if so. construct one. The deterministic algorithm takes time min{ O (N n1/2), O (N + n2 log n)}, where N = ∑i \Ti\, and uses linear space. The randomized algorithm takes time O (N log3 n) and uses linear space. The previous best for this problem was a 1981 O (N n) algorithm by Aho et al. Our faster deterministic algorithm uses a new efficient algorithm for the following interesting dynamic graph problem: Given a graph G with n nodes and m edges and a sequence of b batches of one or more edge deletions, then, after each batch, either find a new component that has just been created or determine that there is no such component. For this problem, we have a simple algorithm with running time O (n2 log n + b0 min{n2, m log n}), where b0 is the number of batches which do not result in a new component. For our particular application b0 ≤ 1. If all edges are deleted, then the best previously known deterministic algorithm requires time O (m √n) to solve this problem. We also present two applications of these consensus tree algorithms which solve other problems in computational evolutionary biology.

Original languageEnglish (US)
Pages (from-to)1-13
Number of pages13
JournalAlgorithmica (New York)
Issue number1
StatePublished - May 1999


  • Algorithms
  • Data structures
  • Evolutionary biology
  • Theory of databases

ASJC Scopus subject areas

  • Computer Graphics and Computer-Aided Design
  • Software
  • Safety, Risk, Reliability and Quality
  • Applied Mathematics

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