Hermite Reciprocity and Self-Duality of Generalized Eagon-Northcott Complexes
Ethan Reed
TL;DR
This work establishes a new self-duality instance for generalized Eagon-Northcott complexes by exploiting a special Hermite reciprocity map in the setting of binary forms. It constructs an embedding of a $\Sym^{b-1}(\varphi|_{V_1 \otimes S})$-based complex into a minimal free resolution, translates the problem via the Bernstein-Gel'fand-Gel'fand correspondence to $E$-modules, and derives a module-theoretic isomorphism $P(V_1) \cong \hat{P}(V_1)(-(b-1))$ that embodies Hermite reciprocity. A key contribution is the introduction of a special Hermite isomorphism $\psi_{b,0}(V_1)$ (not equivalent to previously known formulations) that can be realized explicitly in low dimensions and is used to construct an $E$-module morphism reflecting self-duality. The results connect to Weyman modules and Green's conjecture, extending known self-duality phenomena and providing explicit maps between module structures that illuminate the role of Hermite reciprocity in this setting.
Abstract
Previous examples of self-duality for generalized Eagon-Northcott complexes were given by computing the divisor class group for Hankel determinantal rings. We prove a new case of self-duality of generalized Eagon-Northcott complexes with input being a map defining a Koszul module with nice properties. This choice of Koszul module can be specialized to the Weyman module, which was used in a proof of the generic version of Green's conjecture. In this case, the proof uses a version of Hermite Reciprocity not previously defined in the literature.
