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UID:5392@i2m.univ-amu.fr
DTSTART;TZID=Europe/Paris:20250124T110000
DTEND;TZID=Europe/Paris:20250124T120000
DTSTAMP:20250122T140454Z
URL:https://www.i2m.univ-amu.fr/evenements/seminaire-rauzy-2025-01-24/
SUMMARY:Corentin LUNEL (...): Liens arborescents de Hopf\, théorie des min
 eurs et décidabilité du défaut de genre
DESCRIPTION:Corentin LUNEL: While the problem of computing the genus of a k
 not is now fairly well understood\, no algorithm is known for its four-dim
 ensional variants\, both in the smooth and in the topological locally flat
  category. In this article\, we investigate a class of knots and links cal
 led Hopf arborescent links\, which are obtained as the boundaries of some 
 iterated plumbings of Hopf bands. We show that for such links\, computing 
 the genus defects\, which measure how much the four-dimensional genera dif
 fer from the classical genus\, is decidable. Our proof is non-constructive
 \, and is obtained by proving that Seifert surfaces of Hopf arborescent li
 nks under a relation of minors defined by containment of their Seifert sur
 faces form a well-quasi-order.
CATEGORIES:Séminaire,Rauzy
LOCATION:I2M Saint-Charles - Salle de séminaire\, Université Aix-Marseill
 e\, Campus Saint-Charles\, 3 Place Victor Hugo\, Marseille\, 13003\, Franc
 e
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=Université Aix-Marseille\,
  Campus Saint-Charles\, 3 Place Victor Hugo\, Marseille\, 13003\, France;X
 -APPLE-RADIUS=100;X-TITLE=I2M Saint-Charles - Salle de séminaire:geo:0,0
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