Martin Rubey ; Christian Stump
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Crossings and nestings in set partitions of classical types
dmtcs:2826 -
Discrete Mathematics & Theoretical Computer Science,
January 1, 2010,
DMTCS Proceedings vol. AN, 22nd International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2010)
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https://doi.org/10.46298/dmtcs.2826
Crossings and nestings in set partitions of classical types
Authors: Martin Rubey 1; Christian Stump 2
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Martin Rubey;Christian Stump
1 Institut für Algebra, Zahlentheorie und Diskrete Mathematik
2 Laboratoire de combinatoire et d'informatique mathématique [Montréal]
In this extended abstract, we investigate bijections on various classes of set partitions of classical types that preserve openers and closers. On the one hand we present bijections for types $B$ and $C$ that interchange crossings and nestings, which generalize a construction by Kasraoui and Zeng for type $A$. On the other hand we generalize a bijection to type $B$ and $C$ that interchanges the cardinality of a maximal crossing with the cardinality of a maximal nesting, as given by Chen, Deng, Du, Stanley and Yan for type $A$. For type $D$, we were only able to construct a bijection between non-crossing and non-nesting set partitions. For all classical types we show that the set of openers and the set of closers determine a non-crossing or non-nesting set partition essentially uniquely.