Boundedness of zeros of Sobolev orthogonal polynomials via generalized eigenvalues

Abstract: The main aim of this work is to apply the study of the asymptotic behaviour of generalized eigenvalues between infinite Hermitian definite positive matrices in an important question regarding the location of zeros of Sobolev orthogonal polynomials. In order to do it we introduce matrix Sobolev inner products associated with a set of infinite Hermitian positive definite matrices that generalize a type of Sobolev inner products. These matrix components are not necessarily moment matrices associated to measures. This general framework allows us to study boundedness of multiplication operator in the space of polynomials, that is a sufficient condition for boundedness of zeros of orthogonal polynomials, via this matrix approach. As a consequence of our results we provide a criteria to assure boundedness of the zero set of Sobolev orthogonal polynomials in different situations in terms of the generalized eigenvalues introduced in [10].