Past Seminars- Geometry and Topology

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  • Nir Gadish
    Mon Mar 19, 2018
    4:00 pm
    Hyperplane arrangements are a classical meeting point of topology, combinatorics and representation theory. Generalizing to arrangements of linear subspaces of arbitrary codimension, the theory becomes much more complicated. However, a crucial observation is that many natural sequences of arrangements seem to be defined using a finite amount of...
  • Marc Hoyois
    Mon Mar 12, 2018
    4:00 pm
    The study of vector bundles on algebraic varieties is a classical topic at the intersection of geometry and commutative algebra. In its algebraic form it is the study of finitely generated projective modules over commutative rings. There are many long-standing conjectures and open questions about algebraic vector bundles, such as: is every...
  • Weiwei Wu
    Mon Mar 5, 2018
    4:00 pm
    Seidel's Lagrangian Dehn twist exact sequence has been a cornerstone of the theory of Fukaya categories.  In the last decade, Huybrechts and Thomas discovered a new autoequivalence in the derived cateogry of coherent sheaves using the so-called "projective objects", which are presumably mirrors of Lagrangian projective spaces....
  • Qiongling Li
    Mon Feb 12, 2018
    4:00 pm
    On a complex manifold, a Higgs bundle is a pair containing a holomorphic vector bundle E and a holomorphic End(E)-valued 1-form. In this talk, we focus on nilpotent Higgs bundles, for example, the ones arising from variations of Hodge structures for a deformation family of Kaehler manifolds. We first give an optimal upper bound of the curvature of...
  • Carolyn Abbott
    Mon Feb 5, 2018
    4:00 pm
    Every group admits at least one action by isometries on a hyperbolic metric space, and certain classes of groups admit many different actions on different hyperbolic metric spaces (in fact, often uncountably many).  One such class of groups is the class of so-called acylindrically hyperbolic groups, which contains many interesting groups,...
  • Gabriel Drummond-Cole
    Mon Jan 22, 2018
    4:00 pm
    Configuration spaces of manifolds are often studied using the local model of configurations of Euclidean space. Configuration spaces of graphs have been studied as rigid combinatorial objects. I will describe a model for configuration spaces of cell complexes which combines the best features of both of these traditions, along with...
  • Bena Tshishiku
    Mon Jan 8, 2018
    4:00 pm
    A basic problem in the study of fiber bundles is to compute the ring H*(BDiff(M)) of characteristic classes of bundles with fiber a smooth manifold M. When M is a surface, this problem has ties to algebraic topology, geometric group theory, and algebraic geometry. Currently, we know only a very small percentage of the total cohomology. In this...