PUB - Publikationen an der Universität Bielefeld

We develop a combinatorial theory for the operation of forming the logarithm of generating functions associated with covariant functors on the category of finite sets and bijective maps. This leads to a rather general and flexible exponential principle for labeled combinatorial structures. We also introduce the concept of a topos-like category, which turns out to be a convenient framework for the discussion of a wide range of applications a few of which are studied in detail. (C) 1997 Academic Press.