We introduce ramified coverings of small categories, and we prove three properties of the notion: the Riemann-Hurwitz formula holds for a ramified covering of finite categories, the zeta function of B divides that of E for a ramified covering P: E → B of finite categories, and the nerve of a d-fold ramified covering of small categories is also a simplicial d-fold ramified covering.
- Euler characteristic of categories
- Ramified covering of small categories
- Zeta function of a finite category
ASJC Scopus subject areas
- Mathematics (miscellaneous)