© 2003 by London Mathematical Society
© The London Mathematical Society
Free Lie Algebras and Adams Operations
Department of Mathematics, UMIST PO Box 88, Manchester M60 1QD, bryant{at}umist.ac.uk
Received 15 February 2002. Revision received 21 January 2003.
Let G be a group and K a field. For any finite-dimensional KG-module V and any positive integer n, let Ln(V) denote the nth homogeneous component of the free Lie K-algebra generated by (a basis of) V. Then Ln(V) can be considered as a KG-module, called the nth Lie power of V. The paper is concerned with identifying this module up to isomorphism. A simple formula is obtained which expresses Ln(V) in terms of certain linear functions on the Green ring. When n is not divisible by the characteristic of K these linear functions are Adams operations. Some results are also obtained which clarify the relationship between Adams operations defined by means of exterior powers and symmetric powers and operations introduced by Benson. Some of these results are put into a more general setting in an appendix by Stephen Donkin.