The shifted generic-kernel extension conjecture

Let Vk,qp(i)V^{(i)}_{k,q^p} denote the spectral shift of the Kirillov–Reshetikhin module Vk(i)V^{(i)}_k, and let qpKk(i)q^pK^{(i)}_k denote the corresponding grading shift of its generic kernel. Let o(M,N)\mathfrak{o}(M,N) be the order of the zero at z=1z=1 of the normalized RR-matrix denominator, and let ExtΠ~1\mathop{\mathrm{Ext}}^1_{\widetilde{\Pi}} be the first extension group over the generalized preprojective algebra. Shifted extension conjecture. For any i,jIi,j\in I, k,lZ>0k,l\in\mathbb{Z}_{>0}, and p,sZp,s\in\mathbb{Z},

o(Vk,qp(i),Vl,qs(j))=dimkExtΠ~1(qpKk(i),qsKl(j)).\mathfrak{o}(V^{(i)}_{k,q^p},V^{(j)}_{l,q^s})=\dim_{\Bbbk}\mathop{\mathrm{Ext}}^1_{\widetilde{\Pi}}(q^pK^{(i)}_k,q^sK^{(j)}_l).

This is the shifted reformulation of the unrestricted divisor–extension conjecture, using the compatibility of spectral and grading shifts.

Sources & referencesView supporting material

Primary source

Ryo Fujita and Kota Murakami, “Deformed Cartan matrices and generalized preprojective algebras I: Finite type”, arXiv:2109.07985 (2022).

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