Three interacting families of Fuss-Catalan posets
We will introduce three families of posets depending on a nonnegative integer parameter \(m\), having underlying sets enumerated by the \(m\)-Fuss Catalan numbers. Among these, one is a generalization of Stanley lattices and another one is a generalization of Tamari lattices. We will see how these three families of ...
L-orientations of graphs
summary: An orientation of an (undirected) graph G is an assignment of directions to each edge of G. In this talk, we consider an orientation such that the out-degree of each vertex is contained in a given list. We introduce several relations to graph theory topics and pose our main ...
Formes limites de permutations à motifs interdits
On s'intéresse aux ensembles de permutations à motifs exclus, appelés classes de permutations, qui ont été beaucoup étudiés en combinatoire énumérative. Dans ce travail, à la frontière entre combinatoire et probabilités, on s'intéresse à la limite d'échelle d'une grande permutation aléatoire uniforme dans une classe de ...
PHD defense: A guide book for the traveller on graphs full of blockages
summary: We study NP-hard problems dealing with graphs containing blockages.
We analyze cut problems via the parameterized complexity framework. The size p of the cut is the parameter. Given a set of sources {s_1,...,s_k} and a target t, we propose an algorithm deciding whether a cut of size at ...
Cardinal d'un ensemble de coupure minimal en percolation de premier passage
On considère le modèle de percolation de premier passage sur \(\mathbb{Z}^d\) en dimension \(d\geq 2\) : on associe aux arêtes du graphe une famille de variables i.i.d. positives ou nulles. On interprète la variable aléatoire associée à une arête comme étant sa capacité, i.e., la ...
Optimal curing policy for epidemic spreading over a community network with heterogeneous population
summary: The design of an efficient curing policy, able to stem an epidemic process at an affordable cost, has to account for the structure of the population contact network supporting the contagious process. Thus, we tackle the problem of allocating recovery resources among the population, at the lowest cost possible ...
Permutahedral matchings, zonotopal tilings, and d-partitions
In this talk I will present higher dimensional generalizations of the following three concepts:
- (a) perfect matchings of a hexagonal tiling,
- (b) rhombus tilings of a hexagon, and
- (c) plane partitions.
I will show that these generalizations are equivalent under certain specific bijections. The generalizations of (b) and (c) have ...
Brauer-Thrall Conjectures, Old and New!
\(\tau\)-tilting theory is an elegant-- but technical-- subject in representation theory of associative algebras, with motivations from cluster algebras. It was introduced by Adachi-Iyama-Reiten, in 2014. However, thanks to the recent result of Demonet-Iyama-Jasso, one can fully phrase the concept of \(\tau\)-tilting finiteness in terms of linear algebra ...
Geometry of random permutation factorizations
We study random minimal factorizations of the \(n\)-cycle into transpositions, that is, factorizations of the cycle \((1 2...n)\) into a product of \(n-1\) transpositions. It is known that these factorizations are in bijection with Cayley trees of size \(n\), and therefore that there are \(n^{n-2}\) of them ...
Séminaire ouvert
Lors d'un séminaire ouvert, le thème n'est pas décidé à l'avance. Tous les membres du séminaires sont invités à participer et peuvent proposer le jour même des interventions plus ou moins longues, des démos ou des questions ouvertes au reste de l'équipe.