Structure relations for monic orthogonal polynomials in two discrete variables (Q2470479)

In recent two papers [\textit{J. Rodal, I. Area}, and \textit{E. Godoy}, Integral Transforms Spec. Funct. 16, No. 3, 263--280 (2005; Zbl 1065.33013); and J. Comput. Appl. Math. 200, 722--748 (2007; Zbl 1113.33016)] the authors presented a general approach to investigate the orthogonal polynomial solutions of a second order linear differential equation of hypergeometric type. Continuing this study, the present paper deals with finite-type relations, like first- and second-order structure relations for these monic discrete orthogonal families and their partial differences. Further, ladder operators for raising and lowering the degree but preserving the parameters of these families are built. Finally relations between partial differences of Hahn and Kravchuk polynomials and the polynomials themselves are also explicitly presented.