It is well-known that the classical orthogonal polynomials of Jacobi, Bessel, Laguerre and
Hermite are solutions of a Sturm–Liouville problem of the type where σ and τ are …

We obtain an explicit expression for the Sobolev-type orthogonal polynomials {Qn}
associated with the inner product [Formula: see text], where p (x)=(1− x) α (1+ x) β is the …

We consider the general theory of the modifications of quasi-definite linear functionals by
adding discrete measures. We analyze the existence of the corresponding orthogonal …

Suppose that ν is a given positive measure on-1, 1, and that μ is another measure on the
real line, whose restriction to-1, 1 is ν. We show that one can bound the orthonormal …

We consider special families of orthogonal polynomials satisfying differential equations.
Besides known hypergeometric cases, we look especially for Heun's differential equations …

Given a strongly regular Hankel matrix, and its associated sequence of moments which
defines a quasi-definite moment linear functional, we study the perturbation of a fixed …

In this paper, we study the Krall-type polynomials on non-uniform lattices. For these
polynomials the second order linear difference equation, q-basic series representation and …

We consider the perturbation of the classical Bessel moment functional by the addition of the
linear functional. We give necessary and sufficient conditions in order for this functional to be …

Two infinite families of Cremona maps depending on one real parameter are given. For all
integers $ n\ge 1$ the first family of Cremona maps consists of group elements in $ Bir\left …

When σ is a quasi‐definite moment functional with the monic orthogonal polynomial system
{P n (x)} n= 0∞, we consider a point masses perturbation τ of σ given by τ:= σ+ λ Σ l= 1 m Σ …