2025/02/03 by John C. Baez, Baez, John C.
Mathematics · #Advanced Mathematical Identities #Algebraic Geometry (math.AG) #Category Theory (math.CT) #FOS: Mathematics #Functional Equations Stability Results #Mathematical functions and polynomials #Number Theory (math.NT)
paper · pdf · doi:10.48550/arxiv.2502.01833
openalex publication_date 2025/02/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Though Joyal's species are known to categorify generating functions in enumerative combinatorics, they also categorify zeta functions in algebraic geometry. The reason is that any scheme X of finite type over the integers gives a "zeta species" ZX, and any species F gives a Dirichlet series \widehatF, in such a way that \widehatZX is the arithmetic zeta function of X, a well-known Dirichlet series that encodes the number of points of X over each finite field. Specifically, a ZX-structure on a finite set is a way of making that set into a semisimple commutative ring, say k, and then choosing a k-point of the scheme X. This is an elaboration of joint work with James Dolan.