Counting the Orderings for Multisets in Consecutive Ones Property and PQ-Trees

  • Giovanni Battaglia
  • Roberto Grossi
  • Noemi Scutellà
Conference paper

DOI: 10.1007/978-3-642-22321-1_6

Part of the Lecture Notes in Computer Science book series (LNCS, volume 6795)
Cite this paper as:
Battaglia G., Grossi R., Scutellà N. (2011) Counting the Orderings for Multisets in Consecutive Ones Property and PQ-Trees. In: Mauri G., Leporati A. (eds) Developments in Language Theory. DLT 2011. Lecture Notes in Computer Science, vol 6795. Springer, Berlin, Heidelberg

Abstract

A binary matrix satisfies the consecutive ones property (C1P) if its columns can be permuted such that the 1s in each row of the resulting matrix are consecutive. Equivalently, a family of setsF = {Q1,...,Qm}, where Qi ⊆ R for some universe R, satisfies the C1P if the symbols in R can be permuted such that the elements of each set Qi ∈ F occur consecutively, as a contiguous segment of the permutation of R’s symbols. Motivated by combinatorial problems on sequences with repeated symbols, we consider the C1P version on multisets and prove that counting the orderings (permutations) thus generated is #P-complete. We prove completeness results also for counting the permutations generated by PQ-trees (which are related to the C1P), thus showing that a polynomial-time algorithm is unlikely to exist when dealing with multisets and sequences with repeated symbols.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Giovanni Battaglia
    • 1
  • Roberto Grossi
    • 1
  • Noemi Scutellà
    • 2
  1. 1.Dipartimento di InformaticaUniversità di PisaPisaItaly
  2. 2.List SpAPisaItaly

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