“Deflation of
permutation sets”

LAURENCE BARKER

(BILKENT UNIVERSITY)

__Abstract__: In terms of the idempotents
of the Burnside ring, the actions of isogation, induction, restriction and
inflation are fairly straightforward, but the formula for deflation has some
peculiar combinatorics involving the Moebius function of the given group.
Despite their apparent peculiarity, the deflation numbers are important: they
appear in the formulas for the exponential and Tornehave morphisms.
Furthermore, the simple composition factors of the Burnside functor are
paramatrized by those finite groups whose non-trivial

deflation numbers are all zero; it is not known explicitly which groups satisfy
that condition.

Date : April 1, 2009 (Wednesday)

Time : 13:40-14:30

Place: Room SAZ01