Implementing finite structures in Mathematica via a skeletal topos of finite sets.

Susan B. Niefield Implementing finite structures in Mathematica via a skeletal topos of finite sets. 137-151 2003 35 J. Symb. Comput. 2 http://dx.doi.org/10.1016/S0747-7171(02)00105-0 db/journals/jsc/jsc35.html#Niefield03