Generalized presentation conjecture for quantum symmetric pair coideals

Let XIX \subseteq I be of finite type and let τAutX(A)\tau \in \operatorname{Aut}_X(A) satisfy τ2=idI\tau^2=\operatorname{id}_I and τX=idX\tau|_X=\operatorname{id}_X. For (γ,σ)(F×)I×FI(\boldsymbol\gamma,\boldsymbol\sigma) \in (\mathbb{F}^{\times})^I \times \mathbb{F}^I, let B~\widetilde B be the algebra freely generated over UqnX+Uqhθ(X,τ)U_q\mathfrak n_X^+U_q\mathfrak h^{\theta(X,\tau)} by elements B~i\widetilde B_i, and let Π:B~Uqkγ,σ(X,τ)\Pi:\widetilde B\to U_q\mathfrak k_{\boldsymbol\gamma,\boldsymbol\sigma}(X,\tau) send B~i\widetilde B_i to Bi;γi,σiB_{i;\gamma_i,\sigma_i} and act identically on the coefficient algebra. The elements and relations below are understood with the notation of the source, including λij\lambda_{ij}, Serij\operatorname{Ser}_{ij}, and the ordered monomials B~i\widetilde B_{\boldsymbol i}. Generalized presentation conjecture. There exist elements

C~ij(γ)αi<λijUqnX+Uqhθ(X,τ)B~i\widetilde C_{ij}(\boldsymbol\gamma)\in \sum_{\alpha_{\boldsymbol i}<\lambda_{ij}}U_q\mathfrak n_X^+U_q\mathfrak h^{\theta(X,\tau)}\widetilde B_{\boldsymbol i}

for all iji\ne j such that ker(Π)\ker(\Pi) is generated by

tλB~iq(λ,αi)B~itλ,t_\lambda\widetilde B_i-q^{-(\lambda,\alpha_i)}\widetilde B_i t_\lambda, EiB~jB~jEiδijtiti1qiqi1,E_i\widetilde B_j-\widetilde B_jE_i-\delta_{ij}\frac{t_i-t_i^{-1}}{q_i-q_i^{-1}},

and

Serij(B~i,B~j)C~ij(γ),\operatorname{Ser}_{ij}(\widetilde B_i,\widetilde B_j)-\widetilde C_{ij}(\boldsymbol\gamma),

with the quantifiers and index ranges stated in the source, if and only if (X,τ)GSat(A)(X,\tau)\in\mathcal{G}\operatorname{Sat}(A) and (γ,σ)GSq(\boldsymbol\gamma,\boldsymbol\sigma)\in\mathcal{G}\mathcal{S}_q. Moreover, the C~ij(γ)\widetilde C_{ij}(\boldsymbol\gamma) are independent of σ\boldsymbol\sigma. This proposes a presentation of a broader class of quantum symmetric pair coideals; the source gives no resolution of the if-and-only-if assertion.

Sources & referencesView supporting material

Primary source

Andrea Appel and Bart Vlaar, “Universal K-matrices for quantum Kac-Moody algebras”, arXiv:2007.09218 (2025).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.