Agenda
avril
-
15:0016:00
Strong flip-flatness has emerged as a natural dense analogue of uniform almost-wideness in the context of preservation theorems, but its combinatorial meaning is still not fully understood. In this paper, we study strongly flip-flat graph classes under a weak sparsity assumption, namely the exclusion of a fixed biclique as a subgraph. Our main result shows that a graph class is weakly sparse and strongly flip-flat if and only if it is uniformly almost-wide. The proof transforms bounded families of flips into bounded deletion sets proceeding via an induction on the number of flips rather than on the independence radius. This viewpoint yields a new connection between flip-based decompositions in dense settings and wideness notions from sparse graph theory. As a consequence, we obtain a characterization of strongly flip-flat classes inside structurally bounded expansion classes, confirming the corresponding case of a broader conjecture that strongly flip-flat classes should be exactly the structurally uniformly almost-wide classes.
(Fatemeh Ghasemi) [LACL, Université Paris-Est Créteil]
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Remarks / Remarques
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14:0015:00
A landmark result of Alon and Shapira characterises testable graph properties by showing that every such property can be described via the Szemerédi regularity lemma. Among the many results in graph property testing, the case of (induced) H-freeness has played a particularly central role, both because of its foundational importance and because of its deep connections with graph removal lemmas. In this talk, we present a finer-grained characterisation of the testability of hereditary properties, based on an appropriate clustering phenomenon. As applications, we obtain a characterisation of those hereditary properties that are easily testable by oblivious one-sided error testers, and we identify broad classes of instances for which the triangle removal lemma admits efficient bounds.
Joint work with Cameron Seth.
(Gaia Carenini) [University of Cambridge]
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Remarks / Remarques
Find all the information of the working group on this [ https://graphesetoptimisation.labri.fr/pmwiki.php/Groupe/GT?userlang=en | web page ] .
Retrouvez toutes les informations du GT sur cette [ https://graphesetoptimisation.labri.fr/pmwiki.php/Groupe/GT | page web ] .FrançaisLaBRI/178 -
12:3013:00
L’intervenant est François Godin, chargé de projets : données de la recherche, responsable de l'Atelier bordelais de la donnée de recherche (ABDo) - Service Transversal Soutien à la Recherche (DIRDOC).
Présentation synthétique des principes FAIR et de leur rôle dans l’ouverture des données de recherche. Il vise à clarifier les enjeux, les obligations et les bénéfices associés à une gestion responsable et partageable des données.
Ce format court (30 min) a pour objectif de sensibiliser aux enjeux et pratiques de la science ouverte toute la communauté universitaire de Bordeaux, et particulièrement les chercheurs et doctorants.
Webinaire