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Extended TQ-relations in the Grothendieck ring K0(O)

Establish the extended TQ-relations in K0(O) for all w ∈ W: for any finite-dimensional simple U_q(ĝ)-module V, after replacing each variable Y_{i,a} in the q-character X_q(V) by the specified product [w(ω_i)]·[L(Y_{−w(ω_i), a q^{−1}})]/[L(Y_{w(ω_i), a q})], the resulting expression, once denominators are cleared, equals [V].

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Background

These relations generalize the Baxter-type TQ-relations proved previously for the longest Weyl group element w0. They encode identities among classes of simple modules in the category O derived from substitutions in q-characters using extremal l-weights Y_{w(w_i),a}.

The conjecture is proven for w = w0 and for simple reflections; the general case would yield a Weyl-group–indexed family of spectral descriptions for transfer-matrices via Baxter operators.

References

Conjecture 7.12. Let w E W and let V be a finite-dimensional simple Uq(g)-module. Replace every variable Yi,a, i E I, appearing in the q-character Xq(V) with Yi,a > [w (i )] [L(Y_(w;),aq-1)] [L(Yw(wi),aq;)] By equating the resulting expression with [V] and clearing the denominators, we obtain an algebraic relation in K0(O).

Extremal monomial property of q-characters and polynomiality of the X-series (2504.00260 - Frenkel et al., 31 Mar 2025) in Section 7.4, Conjecture 7.12