Polynomial-kind uniformity conjecture for factorized A2A_2-Leonard pairs

A factorized A2A_2-Leonard pair consists of compatible parameter arrays

Φj=(tx,tx(j),x=0,,Nj;fx(j),gx(j),x=1,,Nj)\Phi_j=(t_x,t_x^\star(j),x=0,\dots,N-j;f_x(j),g_x(j),x=1,\dots,N-j)

and

Ψx=(θj(x),θj,j=0,,Nx;φj(x),ϕj(x),j=1,,Nx),\Psi_x=(\theta_j(x),\theta_j^\star,j=0,\dots,N-x;\varphi_j(x),\phi_j(x),j=1,\dots,N-x),

where the arrays are of type II when their eigenvalues are quadratic in the index. A parameter array is associated to a kind of polynomial from the (q)(q-)Askey scheme. Polynomial-kind uniformity conjecture. To get a factorized Leonard pair, it is necessary that Φj\Phi_j for any jj (respectively, Ψx\Psi_x for any xx) is associated to the same kind of polynomial. The conjecture would strongly restrict the possible combinations of parameter arrays, but the source gives no evidence of a proof or resolution.

Sources & referencesView supporting material

Primary source

Nicolas Crampe and Meri Zaimi, “Factorized A_2-Leonard pair”, arXiv:2312.08312 (2024).

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