Why compactify?

Tamás Hausel

2.10pm-4.00 pm February 8

939 Evans Hall, Berkeley

This is the first introductory and organizing talk of this Berkeley-Stanford working seminar, open to anyone interested. The overall aim is to understand the asymptotics of the metric and in turn to find the "right" compactifications of various open manifolds. "Right" means that certain questions of global analysis on the complete, smooth but open manifold could be understood by analysis, in nice cases topology, of the (usually singular) compactification. Among the manifolds we will consider are various hyparkähler manifolds like quiver varieties, moduli of instantons, monopoles and Higgs bundles. The compactifications which may be treated are: Borel-Satake and various other compactifications of locally symmetric spaces, Uhlenbeck compactifications of moduli of instantons, Tian-Yau compactifications of Ricci-flat Kähler manifolds, Morgan-Shalen compactification of character varieties, Thurston compactification of Teichmüller space, Martin compactifications of Riemannian manifolds, Lerman's symplectic cutting, etc. In this introductory talk I will address three concrete problems arising in string theory (S-duality) and low dimensional topology (SU(n) and SL(2,C) Casson invariants) and indicate how compactifications of certain hyperkähler moduli spaces could help to attack these problems.
LECTURE NOTES ARE AVAILABLE:
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