SYM lecture: An alternative appoach to Witt vectors

This is a talk in our monthly SYM lecture series. It is colloquim style, and aimed at all members of the center. Cake is served at 14:45.

Speaker: Christopher Deninger.

Abstract: Witt vectors are an important algebraic tool in many fields of mathematics. The original construction by Witt is a bit cumbersome using universal polynomials for addition and multiplication whose integrality properties have to be proved. In this description, calculating the sum of 4 simple Witt vectors by hand is the work of an afternoon. In joint work with Joachim Cuntz we found an alternative approach, which at least in the case of perfect F_p - Algebras allows a one line description, addition and multiplication being obvious.

The talk is elementary.