The Euler characteristic of a category
Category Theory
2010-02-04 v1 Algebraic Topology
Combinatorics
Abstract
The Euler characteristic of a finite category is defined and shown to be compatible with Euler characteristics of other types of object, including orbifolds. A formula for the cardinality of the colimit of a diagram of sets is proved, generalizing the classical inclusion-exclusion formula. Both rest on a generalization of Mobius-Rota inversion from posets to categories.
Cite
@article{arxiv.math/0610260,
title = {The Euler characteristic of a category},
author = {Tom Leinster},
journal= {arXiv preprint arXiv:math/0610260},
year = {2010}
}
Comments
24 pages