FUNCTORIAL CONCEPTS OF COMPLEXITY FOR FINITE AUTOMATA For Aurelio, an exacting colleague and a treasured friend since 1972, when he was one of the unfailingly enthusiastic four who traveled weekly from Milan to Perugia for mathematical discussions "fuori programma".
F. William Lawvere · 2004
Some unsolved problems about the classifying topos for Boolean algebras, as well as about the axiomatic arithmetic of finite combinatorial toposes, are closely connected with some simple distinctions between finite automata.