School of Mathematics Colloquium

Central extensions and A^1-fundamental groups

by Dr. Anand Sawant (University of Munich, Germany)

Thursday, September 14, 2017 from to (Asia/Kolkata)
at TIFR, Mumbai ( AG-69 )

Classical results of Matsumoto and Suslin describe the universal central extension of the group of rational points of a split, semisimple, simply connected algebraic group.  These results were later extended by Brylinski and Deligne, who determined the category of central extensions of a reductive group by the second K-theory sheaf K_2.  We will discuss how these classical results can be uniformly explained and generalized using the so-called motivic or A^1-fundamental group of a reductive algebraic group and describe some interesting consequences.  The talk is based on joint work in progress with Fabien Morel.