Tag: Team seminar
Block gluing in Hom shifts and path reconfiguration in graphs
summary: We study some tilings spaces that are defined from graph homomorphisms, called Hom shifts. Compared to general tiling spaces, they look the same in every direction (invariance by rotation and symmetry) and many undecidable problems or questions in tiling spaces seem to become easier for these objects, using graph-theoretical ...
Acyclic colorings of graphs and the probabilistic method
summary: Graph colorings have been extensively studied for the past century, due to the richness of the theory and its numerous applications. Part of the current research focuses on constrained colorings, and how their properties differ from proper colorings. When we require that, in a proper coloring, no (even) cycle ...
Tiling Groups: Emptiness and Aperiodicity
summary: Tilings of the plane or infinite grid have been a rich field of study for many years. Through tiling with local rules, it is even possible to create aperiodicity and embed computation in the plane. But what happens when we begin changing the underlying structure? We will explore how ...
Vingt mille lieues sous les mots
summary: Dans cette présentation, nous découvrirons une partie de l'écosystème de l'océan de la combinatoire de mots, dont l'exploration a commencé depuis plus d'un siècle. À la surface vivent d'abord les mots périodiques, aux propriétés très régulières et simples : ils nous serviront de point d ...
Introduction à l'apprentissage par renforcement
summary: Cet exposé proposera une introduction à l'apprentissage par renfocement, en présentant les fonctions à maximiser et les types d'approches employées. La présentation suivra l'évolution historique du domaine, du Q-Learning au Deep Reinforcement Learning, en passant par des travaux étant devenus populaires tel que AlphaGo. Nous conclurons ...
Strong local rules without labels for Penrose rhombus tilings
summary: The Penrose rhombus tilings are a subshift of tilings of the planefirst defined by R. Penrose. This subshift is crucial in the study of geometrical tilings because, though it was originally defined with 2 rhombus tiles with cuts-and-notches or arrows on the edges, it is an aperiodic subshift with ...
Self-Stabilization and Byzantine Tolerance for Maximal Independent Set
summary: We analyze the impact of transient and Byzantine faults on the construction of a maximal independent set in a general network. We adapt the self-stabilizing algorithm presented by Turau for computing such a vertex set. Our algorithm is self-stabilizing, and also works under the more difficult context of arbitrary ...
A counting argument for graph colouring
summary: In 2010, Moser and Tardos introduced an algorithmic version of the celebrated Lovász Local Lemma using the entropy compression method. Their method is now widely used in the community and has become a standard of the probabilistic method, mainly because it often provides the tightest existential bounds. However, it ...
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 ...
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 ...