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Le Séminaire de Topologie Algébrique a lieu normalement le jeudi à 14h00 et 15h15, dans la salle B-405.
Vous trouverez des indications pour venir à l'Université Paris 13 ici
Jeudi 18 février 2021
10:00 Fathi Ben Aribi (Université Catholique de Louvain)
Résumé
Markov moves, L²-Burau maps and link invariants
Exposé en ligneL²-Burau maps of braids are generalizations of the Burau
representation of braid groups, that A. Conway and I defined in
2018. The coefficients of the L²-Burau matrices may no longer be
Laurent polynomials but instead live in a general non abelian
group ring. We previously linked some of these L²-Burau maps to
L²-Alexander torsions of links, which are powerful but elusive
link invariants.
In these two talks, I will go further and provide answers to a
natural question: how can one define other link invariants from
general L²-Burau maps ? To this end, I studied the influence of
Markov moves of braids on L²-Burau maps, and I computed new
values of L²-determinants via combinatorics on Cayley graphs of
groups.
In the first part of the talk I will recall basic facts about
braid groups, link invariants, the Burau representation and
L²-invariants.
In the second part I will go into more details on how to
construct link invariants from L²-Burau maps.
Jeudi 4 mars 2021
10:00 Tasos Moulinos (Université de Toulouse)
Titre bientôt disponible
Séminaire en ligne
Renseignements : Charles De Clercq et Bruno Vallette