Robert Hartmann
Department of Mathematics and Computer Science
University of Leicester
University Road
Leicester LE1 7RH
UK

Mackey functors and functorial extensions
(preprint)

abstract
Given a finite group $X$ and a normal subgroup $G$ of $X$, we show that 
any Mackey functor $M$ for $X$ induces another Mackey functor $\tld{M}$ 
for $X$ associated to $G$. 
We then consider the question, whether there exists a functorial 
map $\tld{M}\rightarrow M$. In the case that the order of $G$ and the 
index of $G$ in $X$ are relatively prime, we give a sufficient condition 
for the existence of such a map, using canonical 
induction formulae.