English

The Two-Color Ext Soergel Calculus

Representation Theory 2025-05-23 v2 Quantum Algebra

Abstract

We compute Ext groups between Soergel Bimodules associated to the infinite/finite dihedral group for a realization in characteristic 0 and show that they are free right RR-modules. In particular, we obtain an explicit diagrammatic basis for the Hochschild cohomology of indecomposable Soergel Bimodules. We then give a diagrammatic presentation for the corresponding monoidal category of Ext-enhanced Soergel Bimodules. As applications, we explicitly compute HOMFLY homology/triply graded link homology HHH\overline{\mathrm{HHH}} for the connect sum of two Hopf links and the negative torus link T(3,3)T(3,-3) as right RR-modules. Furthermore, we show that the Hochschild cohomology of Soergel Bimodules in finite dihedral type categorifies Gomi's trace, providing a tt-analog of Soergel's Hom Formula in the dihedral setting.

Keywords

Cite

@article{arxiv.2211.07802,
  title  = {The Two-Color Ext Soergel Calculus},
  author = {Cailan Li},
  journal= {arXiv preprint arXiv:2211.07802},
  year   = {2025}
}

Comments

Updated with new computations of HOMFLY homology and fixed typos

R2 v1 2026-06-28T05:54:26.775Z