Abstract
In this paper, we compute the distribution of the first letter statistic on nine avoidance classes of permutations corresponding to two pairs of patterns of length four. In particular, we show that the distribution is the same for each class and is given by the entries of a new Schröder number triangle. This answers in the affirma-tive a recent conjecture of Lin and Kim. We employ a variety of techniques to prove our results, including generating trees, direct bijections and the kernel method. For the latter, we make use of in a creative way what we are trying to show to aid in solving a system of functional equations satisfied by the associated generating functions in three cases.
Original language | American English |
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Pages (from-to) | 305-338 |
Number of pages | 34 |
Journal | Journal of Combinatorics |
Volume | 14 |
Issue number | 3 |
DOIs | |
State | Published - 2023 |
Keywords
- combinatorial statistic
- kernel method
- Pattern avoidance
- AND PHRASES
- INVERSION SEQUENCES
- GENERATING TREES
All Science Journal Classification (ASJC) codes
- Discrete Mathematics and Combinatorics