We meet Thursdays at 2:45–3:45 pm in Whitney Hall 100E. This semester's organizers are James Hyde and Lorenzo Ruffoni. The seminar has an announcement mailing list open to all.

Topics include: geometric group theory, differential geometry and topology, low-dimensional topology, algebraic topology, and homotopy theory.

• 8/20/2026
  Speaker: Yu-Chan Chang (Ohio State)
  Title: Dehn Functions of Bestvina–Brady Groups

  Abstract: Dehn functions are quasi-isometry invariants of finitely presented groups that measure the complexity of the word problem and capture geometric properties of groups. For example, hyperbolic groups are characterized by having linear Dehn function. Subgroups can have larger Dehn functions than their ambient groups. For instance, CAT(0) groups have at most quadratic Dehn function, but their subgroups can have polynomial Dehn functions of arbitrary degree. In this talk, I will review some results on Dehn functions and then present a complete classification of the Dehn functions of Bestvina–Brady groups. This is joint work with Jeronimo Garcia-Mejia and Matteo Migliorini.
  

• 10/15/2026
  no seminar (Fall break)
  

• 10/22/2026
  Speaker: Meenakshy Jyothis (University of Oklahoma)
  Title: TBA

  Abstract: TBA
  

• 11/26/2026
  no seminar (Thanksgiving)
  

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