University of Cambridge > Talks.cam > Algebra and Representation Theory Seminar > Automorphisms of free groups, hairy graphs and modular forms

  Browse A-Z

Log in

Googledetails Microsoftdetails

🔐 Log In

Information on

Subscribing to talksdetails Finding a talkdetails Adding a talkdetails Disseminating talksdetails Help and Documentationdetails

ℹ️ Information

Automorphisms of free groups, hairy graphs and modular forms

Download to your calendar using vCal

  • UserKaren Vogtmann (Cornell)
  • ClockTuesday 07 February 2012, 17:00-18:00
  • HouseMR15.

If you have a question about this talk, please contact Christopher Brookes .

The group  of outer automorphisms of a free group  acts on a space of finite graphs known as Outer space, and a classical theorem of Hurwicz implies that the homology of the quotient space is an invariant of the group. Kontsevich related the homology of this quotient to the Lie algebra cohomology of a certain infinite-dimensional symplectic Lie algebra.  Using this connection, S. Morita discovered a series of new homology classes for Out(F_n).  We reinterpret Morita’s classes in terms of hairy graphs, and show how this leads to the construction of large numbers of new classes, including some based on classical modular forms for SL(2,Z). (joint work with J. Conant and M. Kassabov).

This talk is part of the Algebra and Representation Theory Seminar series.

This talk is included in these lists:

Note that ex-directory lists are not shown.

Other lists

MedImmune, Sir Aaron Klug Building, Granta Park, Cambridge, CB21 6GH Fav MRL meeting rooms 1 & 2, Level 4 Institute of Metabolic Sciences, Addenbrooke’s Treatment Centre (ATC)

Other talks

Kirk Public Lecture: Title TBC Polar Oceans Seminar Talk Title TBC The Importance of Teaching about Science and Religion in a Time of Global Uncertainty Tea and Coffee Break John Kendrew Lecture - Title TBC
 

© 2006-2025 Talks.cam, University of Cambridge. Contact Us | Help and Documentation | Privacy and Publicity