Séminaires : Séminaire de Topologie

Equipe(s) : tga,
Responsables :Catherine Gille et Najib Idrissi
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Salle : 1016
Adresse :Sophie Germain
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Orateur(s) Livio LIECHTI - IMJ-PRG,
Titre Forbidden minor characterisations and the topological 4-genus
Date13/03/2018
Horaire11:00 à 12:00
RésumeFamously, a finite graph is planar exactly if it does not admit two specific graphs as minors. In fact, a characterisation by finitely many forbidden minors exists for any property which passes to minors with respect to a well-quasi-order. In this context, we discuss a minor relation for Seifert surfaces embedded in three-space, defined by isotopy into an incompressible subsurface, and the property to have an equality between the ordinary Seifert genus and the topological 4-genus of the boundary knot. In particular, we characterise this equality in the case of positive braid knots.
Salle1016
AdresseSophie Germain
© IMJ-PRG