Koszul Duality for star-shaped partial Heegaard diagrams

Abstract

By slicing the Heegaard diagram for a given $3$-manifold in a particular way, it is possible to construct $\mathcal{A}_{\infty}$-bimodules, the tensor product of which retrieves the Heegaard Floer homology of the original 3-manifold. The first step in this is to construct algebras corresponding to the individual slices. In this paper, we use the graphical calculus for $\mathcal{A}_{\infty}$-structures introduced in arXiv:2009.05222v3 to construct Koszul dual $\mathcal{A}_{\infty}$ algebras $\mathcal{A}$ and $\mathcal{B}$ for a particular star-shaped class of slice. Using $\mathcal{A}_{\infty}$-bimodules over $\mathcal{A}$ and $\mathcal{B}$, we then verify the Koszul duality relation.