Chennai Mathematical Institute


2.00 pm, Seminar Hall
Automorphism group of a Bott-Samelson variety

B. Narasimha chary
Chennai Mathematical Institute.


Let G be a simple, simply connected algebraic group over the field of complex numbers. Let B be a Borel subgroup of G. Let X(w) be the Schubert variety in G/B corresponding to a element w of the Weyl group. Demazure constructed a desingularization Z(w) of X(w) for each reduced expression of w, which is known as Bott-Samelson variety. Unlike Schubert varieties it is not clear from the construction of Bott-Samelson varieties whether they are independent of the reduced expression of w ?

In this talk, we will discuss the automorphism groups of Bott-Samelson varieties. We also show that Z(w) has unobstructed deformations for general G and Z(w) has no deformations whenever G is simply laced.