We give explicit, characteristic-free constructions of $\mathrm{GL}(V)$-equivariant minimal free resolutions of all isotypic components of the polynomial ring $S = \mathrm{Sym}(V)$ over its $d^{th}$ Veronese subalgebra $S^{(d)}$. These isotypic components come from an action of $\mathbb{Z}/d\mathbb{Z}$ on $S$ for which $S^{(d)}$ is the ring of invariants. The free modules appearing in the resolutions are (base changes of) Schur modules associated to ribbon or border strip diagrams, and the differential comes from a simple degree lowering map on a certain tensor algebra. We use these resolutions to compute $\mathrm{Hom}$ and $\mathrm{Tor}$ between these modules. This is based on joint work with Ayah Almousa, Michael Perlman, Victor Reiner, and Keller VandeBogert.
Equivariant resolutions over Veronese rings
Sasha Pevzner, University of Minnesota, Twin Cities
Authors: Ayah Almousa, Michael Perlman, Alexandra Pevzner, Victor Reiner, Keller VandeBogert
2023 AWM Research Symposium
Combinatorial and Homological Methods in Commutative Algebra [Organized by Francesca Gandini and Selvi Kara]