Wilf classes of pairs of permutations of length 4

Ian Tuan-Yen Le*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Sn1 π2, . . . , πr) denotes the set of permutations of length n that have no subsequence with the same order relations as any of the πi. In this paper we show that Sn(1342, 2143)| = |Sn(3142, 2341)| and Sn(1342, 3124)| = |Sn(1243, 2134)|. These two facts complete the classification of Wilf-equivalence classes for pairs of permutations of length four. In both instances we exhibit bijections between the sets using the idea of a "block", and in the former we find a generating function for |Sn(1342, 2143)|.

Original languageEnglish (US)
JournalElectronic Journal of Combinatorics
Issue number1 R
StatePublished - May 26 2005

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Geometry and Topology
  • Discrete Mathematics and Combinatorics
  • Computational Theory and Mathematics
  • Applied Mathematics


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