Discrete Mathematics & Theoretical Computer Science, Vol 6, No 1 (2003)

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DMTCS vol 6 no 1 (2003), pp. 13-40

Discrete Mathematics & Theoretical Computer Science


Volume 6 n° 1 (2003), pp. 13-40

author:Cedric Chauve
title:A bijection between planar constellations and some colored Lagrangian trees
keywords:Planar maps, trees, enumeration, bijection, Lagrange formula
abstract:Constellations are colored planar maps that generalize different families of maps (planar maps, bipartite planar maps, bi-Eulerian planar maps, planar cacti, ...) and are strongly related to factorizations of permutations. They were recently studied by Bousquet-Melou and Schaeffer who describe a correspondence between these maps and a family of trees, called Eulerian trees. In this paper, we derive from their result a relationship between planar constellations and another family of trees, called stellar trees. This correspondence generalizes a well known result for planar cacti, and shows that planar constellations are colored Lagrangian objects (that is objects that can be enumerated by the Good-Lagrange formula). We then deduce from this result a new formula for the number of planar constellations having a given face distribution, different from the formula one can derive from the results of Bousquet-Melou and Schaeffer, along with systems of functional equations for the generating functions of bipartite and bi-Eulerian planar maps enumerated according to the partition of faces and vertices.

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reference: Cedric Chauve (2003), Constellations are Lagrangian objects: a bijective proof, Discrete Mathematics and Theoretical Computer Science 6, pp. 13-40
bibtex:For a corresponding BibTeX entry, please consider our BibTeX-file.
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Automatically produced on Tue Feb 11 22:52:38 CET 2003 by falk