Regular language constrained sequence alignment revisited

  • Authors:
  • Gregory Kucherov;Tamar Pinhas;Michal Ziv-Ukelson

  • Affiliations:
  • LIFL/CNRS and INRIA Lille Nord-Europe, Villeneuve d'Ascq, France;Department of Computer Science, Ben-Gurion University of the Negev, Be'er Sheva, Israel;Department of Computer Science, Ben-Gurion University of the Negev, Be'er Sheva, Israel

  • Venue:
  • IWOCA'10 Proceedings of the 21st international conference on Combinatorial algorithms
  • Year:
  • 2010

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Abstract

Imposing constraints in the form of a finite automaton or a regular expression is an effective way to incorporate additional a priori knowledge into sequence alignment procedures. With this motivation, Arslan [1] introduced the Regular Language Constrained Sequence Alignment Problem and proposed an O(n2t4) time and O(n2t2 space algorithm for solving it, where n is the length of the input strings and t is the number of states in the non-deterministic automaton, which is given as input. Chung et al. [2] proposed a faster O(n2t3) time algorithm for the same problem. In this paper, we further speed up the algorithms for Regular Language Constrained Sequence Alignment by reducing their worst case time complexity bound to O(n2t3/ log t). This is done by establishing an optimal bound on the size of Straight-Line Programs solving the maxima computation subproblem of the basic dynamic programming algorithm. We also study another solution based on a Steiner Tree computation. While it does not improve the run time complexity in the worst case, our simulations show that both approaches are efficient in practice, especially when the input automata are dense.