Title : The functor of units of Burnside rings for $p$-groups.
Author : Serge Bouc.
Abstract: In this note I describe the structure of the biset functor $B^\times$
sending a $p$-group $P$ to the group of units of its Burnside ring $B(P)$. In
particular, I show that $B^\times$ is a rational biset functor. It follows that
if $P$ is a $p$-group, the structure of $B^\times(P)$ can be read from a
genetic basis of $P$~: the group $B^\times(P)$ is an elementary abelian 2-group
of rank equal to the number isomorphism classes of rational irreducible
representations of $P$ whose type is trivial, cyclic of order 2, or dihedral.