Seminario di algebra e geometria
ore
10:00
presso Seminario II
In this lecture I will introduce the notion of hypermap~: a pair of permutations
representing the embedding of graphs on surfaces.
A nice bijection, due to Ossona de Mendez and Rosenstiehl, showing a coding of hypermaps
by connected permutations, will be presented.
This will be used to give the structure of
a family of polynomials
in two variables defined by
weighted Dyck paths and whose coefficients are related to Stirling numbers.