On the graded singularity category of Abelian quotient singularities, I. Smooth categorical compactification

Abstract

Given a singularity which is the quotient of an affine space $V$ by a finite Abelian group $G \subseteq \mathrm{SL}(V)$, we study the DG enhancement $\mathcal{D}^{b}(\mathrm{tails}(k[V]^G))$ of the bounded derived category of the non-commutative projective space $\mathrm{tails}(k[V]^G)$ and the DG enhancement $\mathcal{D}_{sg}^{\mathbb{Z}}(k[V]^G)$ of its graded singularity category. In this paper, we construct smooth categorical compactifications, in the sense of Efimov, of $\mathcal{D}^b(\mathrm{tails}(k[V]^G))$ and $\mathcal{D}_{sg}^{\mathbb{Z}}(k[V]^G)$ respectively, via the non-commutative crepant resolution of $k[V]^G$. We give explicit constructions of canonical classical generators in the kernels of such compactifications.