
arXiv: math/0504342
We show that matchings avoiding a certain partial pattern 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 matchings avoiding both patterns $12312$ and $121323$ and Schröder paths without peaks at level one, which are counted by the super-Catalan numbers or the little Schröder numbers. A refinement of the super-Catalan numbers is derived by fixing the number of crossings in the matchings. In the sense of Wilf-equivalence, we use the method of generating trees to show that the patterns 12132, 12123, 12321, 12231, 12213 are all equivalent to the pattern $12312$.
Permutations, words, matrices, super-Catalan numbers, Exact enumeration problems, generating functions, Schröder paths, Enumeration in graph theory, 05A05, 05C30, oscillating tableaux, FOS: Mathematics, Mathematics - Combinatorics, Combinatorics (math.CO), Schröder numbers
Permutations, words, matrices, super-Catalan numbers, Exact enumeration problems, generating functions, Schröder paths, Enumeration in graph theory, 05A05, 05C30, oscillating tableaux, FOS: Mathematics, Mathematics - Combinatorics, Combinatorics (math.CO), Schröder numbers
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