On quasi-polynomials counting planar tight maps
Résumé
A tight map is a map with some of its vertices marked, such that every vertex of degree 1 is marked. We give an explicit formula for the number $N_{0,n}(d_1,…,d_n)$ of planar tight maps with $n$ labeled faces of prescribed degrees $d_1,…,d_n$, where a marked vertex is seen as a face of degree 0. It is a quasi-polynomial in $(d_1,…,d_n)$, as shown previously by Norbury. Our derivation is bijective and based on the slice decomposition of planar maps. In the non-bipartite case, we also rely on enumeration results for two-type forests. We discuss the connection with the enumeration of non necessarily tight maps. In particular, we provide a generalization of Tutte's classical slicings formula to all non-bipartite maps.
Domaines
Combinatoire [math.CO]Origine | Fichiers produits par l'(les) auteur(s) |
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