Contravariant Functors on Finite Sets and Stirling Numbers
Theory and applications of categories, The Lambek Festschrift, Tome 6 (1999), pp. 65-76
We characterize the numerical functions which arise as the cardinalities of contravariant functors on finite sets, as those which have a series expansion in terms of Stirling functions. We give a procedure for calculating the coefficients in such series and a concrete test for determining whether a function is of this type. A number of examples are considered.
Classification :
18A22, 05A10.
Keywords: Functor, cardinality, Stirling numbers.
Keywords: Functor, cardinality, Stirling numbers.
@article{TAC_1999_6_a4,
author = {Robert Par\'e},
title = {Contravariant {Functors} on {Finite} {Sets} and {Stirling} {Numbers}},
journal = {Theory and applications of categories},
pages = {65--76},
year = {1999},
volume = {6},
language = {en},
url = {http://geodesic.mathdoc.fr/item/TAC_1999_6_a4/}
}
Robert Paré. Contravariant Functors on Finite Sets and Stirling Numbers. Theory and applications of categories, The Lambek Festschrift, Tome 6 (1999), pp. 65-76. http://geodesic.mathdoc.fr/item/TAC_1999_6_a4/