Rebocho, M. N.Filipuk, Galina2020-02-042020-02-042018G. Filipuk and M.N. Rebocho, Symmetric semi-classical orthogonal polynomials of class one on q-quadratic lattices, Formal and analytic solutions of diff. equations, 251-261, Springer Proc. Math. Stat., 256, Springer, Cham, 2018.http://hdl.handle.net/10400.6/8994In this paper we study discrete semi-classical orthogonal polynomials on non-uniform lattices. In the symmetric class one case we give a closed form expression for the recurrence coefficients of orthogonal polynomials..engOrthogonal polynomialsDivided-difference operatorNon-uniform latticesSemi-classical classpreprint