Discrete Mathematics & Theoretical Computer Science 
We define and consider $k$distant crossings and nestings for matchings and set partitions, which are a variation of crossings and nestings in which the distance between vertices is important. By modifying an involution of Kasraoui and Zeng (Electronic J. Combinatorics 2006, research paper 33), we show that the joint distribution of $k$distant crossings and nestings is symmetric. We also study the numbers of $k$distant noncrossing matchings and partitions for small $k$, which are counted by wellknown sequences, as well as the orthogonal polynomials related to $k$distant noncrossing matchings and partitions. We extend Chen et al.'s $r$crossings and enhanced $r$crossings.
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IsRelatedTo ARXIV math/0510676 Source : ScholeXplorer IsRelatedTo DOI 10.1016/j.aam.2005.12.006 Source : ScholeXplorer IsRelatedTo DOI 10.48550/arxiv.math/0510676
