Tag: Combi seminar

Bijections for tree-decorated maps and applications to random maps

-- Luis Fredes (LaBRI, Bordeaux)

We introduce a new family of maps, namely tree-decorated maps where the tree is not necessarily spanning. To study this class of maps, we define a bijection which allows us to deduce combinatorial results, recovering as a corollary some results about spanning-tree decorated maps, and to understand local limits. Finally ...

Synchronizing codes, finite monoids of matrices and unambiguous automata

-- Andrew Ryzhikov (IGM, Paris-est)

We introduce a new family of maps, namely tree-decorated maps where the tree is not necessarily spanning. To study this class of maps, we define a bijection which allows us to deduce combinatorial results, recovering as a corollary some results about spanning-tree decorated maps, and to understand local limits. Finally ...

Des tresses aux amas via la dualité de Koszul

-- Matthieu Josuat-Vergès (UPEM)

Il est bien connu que le groupe de tresses admet une présentations avec des générateurs qui satisfont les relations de tresses. On peut voir ces générateurs comme échangeant deux brins voisins du point de vue géométrique. Une autre présentation, due à Birman, Ko, Lee, consiste à regarder un ensemble plus ...

L-Convex Polyominoes are Recognizable in Real Time by 2D Cellular Automata

-- Anaël Grandjean (Université Paris-Est Créteil)

This is a joint work with Victor Poupet where we investigate the recognition power of cellular automata in real time. A polyomino is said to be L-convex if any two of its cells are connected by a 4-connected inner path that changes direction at most once. The 2-dimensional language representing ...

Asymptotic distribution of parameters in random maps

-- Sergey Dovgal (LIPN Univ. Paris 13)

In this joint work with Olivier Bodini, Julien Courtiel, and Hsien-Kuei Hwang, we consider random rooted maps without regard to their genus. We address the problem of limiting distributions for six different parameters: - vertices - leaves - loops - root edges - root isthmic constructions - root vertex degree Each parameter has a different limiting ...

Séminaire ouvert

-- Toute l'équipe (LIX et GALAC)

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.

Séminaire ouvert

-- Toute l'équipe (LIX et GALAC)

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.

Mobius functions for real hyperplane arrangements.

-- Marcelo Aguiar (Cornell Univ.)

We discuss the beginnings of a theory of noncommutative Mobius functions and its connections to the structure of the algebra of faces of a hyperplane arrangement. It is to be seen as a generalization of the theory of Mobius functions for lattices, developed by Rota and his school in the ...

A proof-theoretic analysis of the rotation lattice of binary trees

-- Noam Zeilberger (Birmingham University)

Join seminar with the Parsifal team The classical Tamari lattice Yn is defined as the set of binary trees with n internal nodes, with the partial ordering induced by the (right) rotation operation. It is not obvious why Yn is a lattice, but this was first proved by Haya Friedman ...

Generalized Jucys-Murphy elements and canonical idempotents in towers of algebras

-- Aaron Lauve (Loyola Univ., Chicago)

The collection of symmetric group algebras serves as a motivating example for what I'll call a multiplicity-free tower of finite dimensional algebras. Any such family has a canonical complete set of pairwise orthogonal primitive idempotents stemming from its representation theory. In the case of the symmetric group algebras, these ...

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