English

Matchings Avoiding Partial Patterns

Combinatorics 2007-05-23 v1

Abstract

We show that matchings avoiding certain partial patterns are counted by the 3-Catalan numbers. We give a characterization of 12312-avoiding matchings in terms of restrictions on the corresponding oscillating tableaux. We also find a bijection between Schr\"oder paths without peaks at level one and matchings avoiding both patterns 12312 and 121323. Such objects are counted by the super-Catalan numbers or the little Schr\"{o}der numbers. A refinement of the super-Catalan numbers is obtained by fixing the number of crossings in the matchings. In the sense of Wilf-equivalence, we find that the patterns 12132, 12123, 12321, 12231, 12213 are equivalent to 12312.

Keywords

Cite

@article{arxiv.math/0504342,
  title  = {Matchings Avoiding Partial Patterns},
  author = {William Y. C. Chen and Toufik Mansour and Sherry H. F. Yan},
  journal= {arXiv preprint arXiv:math/0504342},
  year   = {2007}
}

Comments

17 pages, 7 figures