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Geometry-Topology Seminar

Thursday, October 22, 2020 - 4:30pm

Matt Ando



University of Pennsylvania


The Zoom link is: This same Zoom link will apply for future talks as well. It is set to open at 4 PM so that speakers can come on early and check out their technology setups. The talks will begin at 4:30 PM. We will also stay afterwards, say from 5:30 - 6 PM to chat with one another, as an online substitute for going out to dinner with our speakers. We encourage everyone to have a nice bottle of wine at hand for that social half hour. For further information about the seminar, please contact Mona Merling (, Davi Maximo ( or Herman Gluck (

Our understanding of the geometry associated with the second Chern class has gradually increased over the last 25 years. It appears in many contexts: it is associated with a 2-dimensional topological field theory and with the Wess-Zumino-Witten model. It plays an essential role in the construction of the String 2-group, and so it has a deep and still imperfectly understood relationship with elliptic cohomology. I’ll give a survey of some ways of thinking about the 2nd Chern class and sketch how some of these approaches are related to each other.