Orateur
Vladimir FOCK
(Université de Strasbourg)
Description
Steinberg symbol is a function of two elements of a ring satisfying very simple conditions. It's main application so far is in number theory and algebraic K-theory. We will show that it is a very transparent construction and it gives the central extension giving just infinite Heisenberg group. The same symbol can be used to define an explicit formula for central extension of affine Lie groups, but for this purpose one can use special (cluster) coordinates for simple Lie groups.
