Conjecture on Demazure crystal expansions of generalized minors

Let II be the index set, let w0w_0 be the longest Weyl-group element, and let Θi(c)\Theta_{\mathbf i}^-(c), π+\pi^+, η\eta, αi(t)\alpha_i(t), and the generalized minors ΔuΛ,vΛ\Delta_{u\Lambda,v\Lambda} and characters χi\chi_i be as in the construction. For a sign p=(pi,j)ijp=(p_{i,j})_{i\ne j}, write Y(p)\mathcal Y(p) for the associated monomial realization, and let mb(c)Y(p)m_b(c)\in\mathcal Y(p) denote the monomial corresponding to a crystal element bb.

Demazure-crystal expansion conjecture. There exists a reduced expression of the longest Weyl-group element i=(i1,,iN)\mathbf i=(i_1,\ldots,i_N) and a sign p=(pi,j)ijp=(p_{i,j})_{i\ne j} such that, for every iIi\in I, there are Demazure crystals Bw(i)B(Λk)B^-_w(i)\subset B(\Lambda_k) and Bw+(i)B(Λj)B^+_{w'}(i)\subset B(\Lambda_j), together with positive integers aba_b and aba_{b'}, satisfying

χi(π+(w01tΘi(c)))=Δw0Λi,siΛi(Θi(c))=bBw(i)abmb(c),\chi_i(\pi^+(w_0^{-1}t\Theta_{\mathbf i}^-(c)))=\Delta_{w_0\Lambda_i,s_i\Lambda_i}(\Theta_{\mathbf i}^-(c))=\sum_{b\in B^-_w(i)}a_bm_b(c), χi(π+(w01η(tΘi(c))))=αi(t)Δw0siΛi,Λi(Θi(c))=αi(t)bBw+(i)abmb(c).\chi_i(\pi^+(w_0^{-1}\eta(t\Theta_{\mathbf i}^-(c))))=\alpha_i(t)\Delta_{w_0s_i\Lambda_i,\Lambda_i}(\Theta_{\mathbf i}^-(c))=\alpha_i(t)\sum_{b'\in B^+_{w'}(i)}a_{b'}m_{b'}(c).

This conjecture proposes a uniform description of the relevant generalized minors by monomials indexed by Demazure crystals. The preceding type AnA_n calculations provide explicit supporting examples, while the general existence of the reduced word, sign, and Demazure-crystal expansions remains unresolved in the supplied source.

Sources & referencesView supporting material

Primary source

Toshiki Nakashima, “Decorations on Geometric Crystals and Monomial Realizations of Crystal Bases for Classical Groups”, arXiv:1301.7301 (2013).

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