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{\Large המחלקה למתמטיקה, בן-גוריון}

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{\Huge קולוקוויום}\\[0.2\baselineskip]

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\textbf{ב}\emph{יום שלישי,  9 בדצמבר, 2025}
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\textbf{בשעה} \emph{14:30 -- 15:30}
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\textbf{ב}\emph{Math -101}

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ההרצאה

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{\Large\bfseries Virtual homological torsion in low dimensions\par}
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תינתן על-ידי
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{\large\scshape Jonathan Fruchter 
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  (University of Bonn)
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\textbf{תקציר:}
  A long-standing conjecture of Nicolas Bergeron and Akshay Venkatesh
predicts that in closed hyperbolic 3-manifolds, the amount of torsion in
the first homology of finite-sheeted normal covers should grow
exponentially with the degree of the cover as the covers become larger,
at a rate reflecting the volume of the manifold. Yet no finitely
presented residually finite group is known to exhibit exponential
torsion growth in first homology along an exhausting chain of
finite-index normal subgroups.

In this talk I will explain how a two-dimensional lens offers a clearer
view of some of the underlying mechanisms that create homological
torsion in finite covers, and why obtaining exponential growth may be
more tractable in this setting. I will also discuss how these ideas
connect to the question of profinite rigidity: how much information
about a group is encoded in its finite quotients.
  


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