jeu. 13 mars 2025 -- Clément Chenevière (LISN, GALaC)

summary:

Les treillis cambriens, introduits par N. Reading en 2006, sont une généralisation du treillis de Tamari, à tout choix d'élément de Coxeter, dans tout groupe de Coxeter fini. Le treillis de Tamari correspond au "type A linéaire". Ces ordres partiels admettent plusieurs descriptions, non trivialement équivalentes. Celles-ci donnent ...

ven. 21 février 2025 -- Quentin Chuet (LISN, GALaC)

summary: Given a graph \(G\) of maximum degree \(\Delta\), the proper colouring problem asks for the minimum number of colours that can be assigned to the vertices of \(G\) such that no pair of adjacent vertices are given the same colour; it is easy to show that at most \(\Delta ...

ven. 14 février 2025 -- Pacôme Perrotin (LISN, Galac)

summary: Plane-walking automata were introduced by Salo & Törma to recognise languages of two-dimensional infinite words (subshifts), the counterpart of 4-way finite automata for two-dimensional finite words. We extend the model to allow for nondeterminism and alternation of quantifiers. We prove that the recognised subshifts form a strict subclass of sofic ...

jeu. 23 janvier 2025 -- Hugo Jacob (LaBRI)

summary: Tree-partitions are graph decompositions that correspond to mapping vertices to nodes of a tree in such a way that adjacent vertices in the graph are either mapped to adjacent nodes of the tree or to the same node. The width of a tree-partition is the maximum number of vertices ...