Tuesday's Topology Seminar talk will be by Andrew Salch,
from 2-3 in the Nelson Room.

Title: The action of the Morava stabilizer group on the coefficients of Morava E-theory

Abstract: It is an old problem, in stable homotopy theory and in arithmetic geometry, to give an explicit formula for the action of the automorphism group of a finite-height formal group law on its Lubin–Tate deformation ring. Most papers on this subject have focused on calculating approximations to the action in the first nontrivial case, the case of height 2. In this talk I give a complete solution to this problem at height 2 at all primes, by giving an explicit, elementary closed formula for this group action. More generally, I will give an explicit, elementary closed formula for the action of the full Morava stabilizer group on the coefficients of Morava E-theory, at height 2. The formula is of a combinatorial nature: it is a sum over certain labelled ordered trees.