Representations of fundamental groups of surfaces
 
 
Description:  We consider representations of the fundamental group of a closed surface in the group SL(2,R). To each such representation one can associate an integer invariant called the Toledo invariant. A theorem of J. Milnor says that the absolute value of the Toledo invariant is less than or equal to g-1, where g is the genus of the surface, and a theorem of W. Goldman says that two representations can be continuously deformed into each other if and only if they have the same Toledo invariant.
In the seminar we shall explain the concepts and results mentioned above. Moreover, time permitting, we shall indicate how methods of holomorphic geometry can be used to study such questions through Higgs bundles.
Date:  2018-11-23
Start Time:   15:30
Speaker:  Peter Gothen (CMUP, Univ Porto)
Institution:  CMUP, University of Porto
Place:  Sala 2.5, DMat UC
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