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UID:20250701T195834EDT-3039l3rP8F@132.216.98.100
DTSTAMP:20250701T235834Z
DESCRIPTION: \n\nTitle: Algebraic fibring and L^2-Betti numbers\n\nAbstract
 : A celebrated theorem of Stallings states that if G is the fundamental gr
 oup of a 3-manifold M\, then G maps to Z with finitely generated kernel if
  and only if M fibres over the circle. In light of this theorem\, we say t
 hat a group G algebraically fibres if it maps to Z with finitely generated
  kernel. In 2020\, Kielak showed that a RFRS group virtually algebraically
  fibres if and only if its first L^2-Betti number vanishes\, generalising 
 Agol's fibring crietrion for 3-manifolds. In this talk\, we will present a
  generalisation of this theorem\, which relates the vanishing of the highe
 r L^2-Betti numbers to higher finiteness properties of the kernel in the a
 lgebraic fibration. We will also introduce positive characteristic variant
 s of L^2-Betti numbers and use them to present a positive characteristic v
 ersion of our main theorem.\n\n \n
DTSTART:20230322T190000Z
DTEND:20230322T200000Z
LOCATION:Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue Sherbrooke 
 Ouest
SUMMARY:Sam Fischer (Oxford University)
URL:/mathstat/channels/event/sam-fischer-oxford-univer
 sity-347109
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