CATEGORIFYING RATIONALIZATION

We construct, for any set of primes $S$ , a triangulated category (in fact a stable $\infty$ -category) whose Grothendieck group is $S^{-1}\mathbf{Z}$ . More generally, for any exact $\infty$ -category $E$ , we construct an exact $\infty$ -category $S^{-1}E$ of equivariant sheaves on the Cantor space with respect to an action of a dense subgroup of the circle. We show that this $\infty$ -category is precisely the result of categorifying division by the primes in $S$ . In particular, $K_{n}(S^{-1}E)\cong S^{-1}K_{n}(E)$ .

Moduli of equivariant sheaves and Kronecker–McKay modules

We extend Álvarez-Cónsul and King description of moduli of sheaves over projective schemes to moduli of equivariant sheaves over projective Γ-schemes, for a finite group Γ. We introduce the notion of Kronecker–McKay modules and construct the moduli of equivariant sheaves using a natural functor from the category of equivariant sheaves to the category of Kronecker–McKay modules. Following Álvarez-Cónsul and King, we also study theta functions and homogeneous co-ordinates of moduli of equivariant sheaves.