Bijective link between Chapoton's new intervals and bipartite planar maps

Simple formulas for constellations and bipartite maps with prescribed degrees

We obtain simple quadratic recurrence formulas counting bipartite maps on surfaces with prescribed degrees (in particular, $2k$-angulations), and constellations. These formulas are the fastest known way of computing these numbers. Our work is a natural extension of previous works on integrable hierarchies (2-Toda and KP), namely the Pandharipande recursion for Hurwitz numbers (proven by Okounkov and simplified by Dubrovin-Yang-Zagier), as well as formulas for several models of maps (Goulden-Jackson, Carrell-Chapuy, Kazarian-Zograf). As for those formulas, a bijective interpretation is still to…

A new combinatorial identity for unicellular maps, via a direct bijective approach

A unicellular map, or one-face map, is a graph embedded in an orientable surface such that its complement is a topological disk. In this paper, we give a new viewpoint to the structure of these objects, by describing a decomposition of any unicellular map into a unicellular map of smaller genus. This gives a new combinatorial identity for the number $ε_g(n)$ of unicellular maps of size $n$ and genus $g$. Contrarily to the Harer-Zagier recurrence formula, this identity is recursive in only one parameter (the genus). Iterating the construction gives an explicit bijection between unicellular maps…

The number of intervals in the m-Tamari lattices

An m-ballot path of size n is a path on the square grid consisting of north and east steps, starting at (0,0), ending at (mn,n), and never going below the line {x=my}. The set of these paths can be equipped with a lattice structure, called the m-Tamari lattice, which generalizes the usual Tamari lattice obtained when m=1. We prove that the number of intervals in this lattice is $$ \frac {m+1}{n(mn+1)} {(m+1)^2 n+m\choose n-1}. $$ This formula was recently conjectured by Bergeron in connection with the study of coinvariant spaces. The case m=1 was proved a few years ago by Chapoton. Our proof i…

二部地图的开花双射：一种基于定向的新方法及其在伊辛模型中的应用

Blossoming bijection for bipartite maps: a new approach via orientations and applications to the Ising model

本文通过引入推广欧拉定向的二部地图定向族，将 Bousquet-Mélou 和 Schaeffer 的双射推广到多类二部地图，并为带伊辛模型的四次地图生成级数给出正整数系数的有理拉格朗日参数化。

Unified bijections for maps with prescribed degrees and girth

This article presents unified bijective constructions for planar maps, with control on the face degrees and on the girth. Recall that the girth is the length of the smallest cycle, so that maps of girth at least $d=1,2,3$ are respectively the general, loopless, and simple maps. For each positive integer $d$, we obtain a bijection for the class of plane maps (maps with one distinguished root-face) of girth $d$ having a root-face of degree $d$. We then obtain more general bijective constructions for annular maps (maps with two distinguished root-faces) of girth at least $d$. Our bijections assoc…

关于计数平面紧映射的拟多项式

On quasi-polynomials counting planar tight maps

本文利用平面映射的切片分解与双射方法，给出了计数具有指定面度数的平面紧映射的拟多项式显式公式，并将Tutte切片公式推广至所有非二分映射。

A bijection for rooted maps on orientable surfaces

The enumeration of maps and the study of uniform random maps have been classical topics of combinatorics and statistical physics ever since the seminal work of Tutte in the sixties. Following the bijective approach initiated by Cori and Vauquelin in the eighties, we describe a bijection between rooted maps, or rooted bipartite quadrangulations, on a surface of genus g and some simpler objects that generalize plane trees. Thanks to a rerooting argument, our bijection allows to compute the generating series of rooted maps on a surface of genus g with respect to the number of edges, and to recove…

Orientations and bijections for toroidal maps with prescribed face-degrees and essential girth

We present unified bijections for maps on the torus with control on the face-degrees and essential girth (girth of the periodic planar representation). A first step is to show that for d>=3 every toroidal d-angulation of essential girth d can be endowed with a certain "canonical" orientation (formulated as a weight-assignment on the half-edges). Using an adaptation of a construction by Bernardi and Chapuy, we can then derive a bijection between face-rooted toroidal d-angulations of essential girth d (with the condition that, apart from the root-face contour, no other closed walk of length d en…

The structure of unicellular maps, and a connection between maps of positive genus and planar labelled trees

A unicellular map is a map which has only one face. We give a bijection between a dominant subset of rooted unicellular maps of fixed genus and a set of rooted plane trees with distinguished vertices. The bijection applies as well to the case of labelled unicellular maps, which are related to all rooted maps by Marcus and Schaeffer's bijection. This gives an immediate derivation of the asymptotic number of unicellular maps of given genus, and a simple bijective proof of a formula of Lehman and Walsh on the number of triangulations with one vertex. From the labelled case, we deduce an expressio…

两个集合上的最终常数映射与Nilpotent对

Eventually constant maps for two sets and nilpotent pairs

本文通过双射关系，将两个集合上的最终常数映射与生成树联系起来，并扩展了Cayley公式和Leinster的工作，推导出nilpotent对数量的公式。

偶数个最终常数映射与 nilpotent 对

Pairs of eventually constant maps and nilpotent pairs

本文研究了有限维向量空间间算子对的 nilpotent 性概率及最终常数映射的数量关系。