On a conjecture of Lin and Kim concerning a refinement of Schröder numbers

T Mansour, M Shattuck

Research output: Contribution to journalArticlepeer-review


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 Schro center dot der number triangle. This answers in the affirmative 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 languageEnglish
Pages (from-to)305-338
Number of pages34
JournalJournal of Combinatorics
Issue number3
StatePublished - 2023

Bibliographical note

Times Cited in Web of Science Core Collection: 0 Total Times Cited: 0 Cited Reference Count: 20


  • Pattern avoidance
  • combinatorial statistic
  • kernel method


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