Differential equation for Jacobi-Pineiro polynomials

Abstract

For $r\in \Z_{\geq 0}$, we present a linear differential operator %$(\di)^{r+1}+ a_1(x)(\di)^{r}+...+a_{r+1}(x)$ of order $r+1$ with rational coefficients and depending on parameters. This operator annihilates the $r$-multiple Jacobi-Piñeiro polynomial. For integer values of parameters satisfying suitable inequalities, it is the unique Fuchsian operator with kernel consisting of polynomials only and having three singular points at $x=0, 1, \infty$ with arbitrary non-negative integer exponents $0, m_1+1, >..., m_1+...+m_r+r$ at $x=0$, special exponents $0, k+1, k+2,..., k+r$ at $x=1$ and arbitrary exponents at $x=\infty$.