Topological Models for Categories Associated with the Weighted Projective Lines of Type $(2,2,2,2)$

Abstract

We construct a geometric model for the derived category of the weighted projective line $\mathbb{CP}^1_{\omega}$ of type $(2,2,2,2)$ using a graded sphere with four binaries. More precisely, we give a bijection between the set of indecomposable rigid objects and the set of certain arcs, such that the dimensions of $\operatorname{Hom}$-spaces are computed by oriented intersection numbers. As applications, we provide a geometric realization of the indecomposable rigid objects in the cluster category $\mathcal{C}(\mathbb{CP}^1_{\omega})$ via tagged arcs on the four-punctured sphere, with $\operatorname{Hom}$-space dimensions given by tagged intersection numbers. When the weighted points of $\mathbb{CP}^1_{\omega}$ are $(0,1,\infty,\frac{1}{2})$, both correspondences are compatible with the natural actions of the automorphism groups and the corresponding mapping class groups.