# Homotopy finiteness of some DG categories from algebraic geometry

### Alexander I. Efimov

Steklov Mathematical Institute of RAS and National University Higher School of Mathematics, Moscow, Russia

## Abstract

In this paper, we prove that the bounded derived category $D_{coh}(Y)$ of coherent sheaves on a separated scheme $Y$ of finite type over a field k of characteristic zero is homotopically finitely presented. This confirms a conjecture of Kontsevich. We actually prove a stronger statement: $D_{coh}(Y)$ is equivalent to a DG quotient $D_{coh}(Y~)/T,$ where $Y~$ is some smooth and proper variety, and the subcategory $T$ is generated by a single object.

The proof uses categorical resolution of singularities of Kuznetsov and Lunts [KL], and a theorem of Orlov [Or1] stating that the class of geometric smooth and proper DG categories is stable under gluing.

We also prove the analogous result for $Z/2$-graded DG categories of coherent matrix factorizations on such schemes. In this case instead of $D_{coh}(Y~)$ we have a semi-orthogonal gluing of a finite number of DG categories of matrix factorizations on smooth varieties, proper over $A_{k}$.

## Cite this article

Alexander I. Efimov, Homotopy finiteness of some DG categories from algebraic geometry. J. Eur. Math. Soc. 22 (2020), no. 9, pp. 2879–2942

DOI 10.4171/JEMS/979