(1, 1)-q-coherent pairs

In this paper, we introduce the concept of (1, 1)-q-coherent pair of linear functionals \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$(\mathcal{U},\mathcal{V})$\end{document} as the q-analogue to the generalized coherent pair studied by Delgado and Marcellán in (Methods Appl Anal 11(2):273–266, 2004). This means that their corresponding sequences of monic orthogonal polynomials {Pn(x)}n ≥ 0 and {Rn(x)}n ≥ 0 satisfy \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \frac{\left(D_qP_{n+1}\right)(x)}{[n+1]_q} + a_{n}\frac{\left(D_qP_{n}\right)(x)}{[n]_q} = R_{n}(x) + b_{\!n}R_{n-1}(x) \,, \quad\, a_{n}\neq0,\,\, n\geq1, $$\end{document}\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$[n]_q=\frac{q^n-1}{q-1}$\end{document}, 0 < q < 1. We prove that if a pair of regular linear functionals \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$(\mathcal{U},\mathcal{V})$\end{document} is a (1, 1)-q-coherent pair, then at least one of them must be q-semiclassical of class at most 1, and these functionals are related by an expression \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sigma(x)\mathcal{U}=\rho(x)\mathcal{V}$\end{document} where σ(x) and ρ(x) are polynomials of degrees ≤ 3 and 1, respectively. Finally, the q-classical case is studied.