# Triangulated surfaces in triangulated categories

### Tobias Dyckerhoff

University of Bonn, Germany### Mikhail Kapranov

IPMU, Kashiwa, Japan

## Abstract

For a triangulated category $A$ with a 2-periodic dg-enhancement and a triangulated oriented marked surface $S$, we introduce a dg-category $F(S,A)$ parametrizing systems of exact triangles in $A$ labelled by triangles of $S$. Our main result is that $F(S,A)$ is independent of the choice of a triangulation of $S$ up to essentially unique Morita equivalence. In particular, it admits a canonical action of the mapping class group. The proof is based on general properties of cyclic 2-Segal spaces.

In the simplest case, where $A$ is the category of 2-periodic complexes of vector spaces, $F(S,A)$ turns out to be a purely topological model for the Fukaya category of the surface $S$. Therefore, our construction can be seen as implementing a 2-dimensional instance of Kontsevich's program on localizing the Fukaya category along a singular Lagrangian spine.

## Cite this article

Tobias Dyckerhoff, Mikhail Kapranov, Triangulated surfaces in triangulated categories. J. Eur. Math. Soc. 20 (2018), no. 6, pp. 1473–1524

DOI 10.4171/JEMS/791