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  1. Home > Articles & Issues >
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  3. Another bijection be ...
Conference paper

Another bijection between $2$-triangulations and pairs of non-crossing Dyck paths

Carlos M. Nicolás (1)
(1) Department of Mathematics and Statistics
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Imported on
January 31, 2017
Published on
December 31, 2008
Last modified on
March 31, 2025
Volume
DMTCS Proceedings vol. AK, 21st International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2009)
Proceedings
DOI
10.46298/dmtcs.2683
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https://about.hal.science/hal-authorisation-v1
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Another bijection between $2$-triangulations and pairs of non-crossing Dyck paths

Carlos M. Nicolás (1)
(1) Department of Mathematics and Statistics
Abstract
English
A $k$-triangulation of the $n$-gon is a maximal set of diagonals of the $n$-gon containing no subset of $k+1$ mutually crossing diagonals. The number of $k$-triangulations of the $n$-gon, determined by Jakob Jonsson, is equal to a $k \times k$ Hankel determinant of Catalan numbers. This determinant is also equal to the number of $k$ non-crossing Dyck paths of semi-length $n-2k$. This brings up the problem of finding a combinatorial bijection between these two sets. In FPSAC 2007, Elizalde presented such a bijection for the case $k=2$. We construct another bijection for this case that is stronger and simpler that Elizalde's. The bijection preserves two sets of parameters, degrees and generalized returns. As a corollary, we generalize Jonsson's formula for $k=2$ by counting the number of $2$-triangulations of the $n$-gon with a given degree at a fixed vertex.
French
Une $k$-triangulation du $n$-gon est un ensemble maximal de diagonales du $n$-gon ne contenant pas de sous-ensemble de $k+1$ diagonales mutuellement croisant. Le nombre de $k$-triangulations du $n$-gon, déterminé par Jakob Jonsson, est égal à un déterminant de Hankel $k \times k$ de nombres de Catalan. Ce déterminant est aussi égal au nombre de $k$ chemins de Dyck de largo $n-2k$ que ne pas se croiser. Cela porte le problème de trouver une bijection de type combinatoire entre ces deux ensembles. À la FPSAC 2007, Elizalde a présenté une telle bijection pour le cas $k = 2$. Nous construisons une autre bijection pour ce cas qui est plus forte et plus simple que de l'Elizalde. La bijection conserve deux ensembles de paramètres, les degré et les retours généralisée. De ce, nous généralisons la formule de Jonsson pour $k = 2$ en comptant le nombre de $2$-triangulations du $n$-gon avec un degré à un vertex fixe.
Keywords
  • [MATH.MATH-CO]Mathematics [math]/Combinatorics [math.CO]
  • [INFO.INFO-DM]Computer Science [cs]/Discrete Mathematics [cs.DM]
  • $k$-triangulations
  • non-crossing Dyck paths
  • combinatorial bijection.
Cited by

Source: OpenCitations

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    Advances in Applied Mathematics

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    Journal reference : Volume 47, 2010, pp. 57-87

    DOI : 10.1016/j.aam.2009.11.013
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