Journal of Applied Mathematics 
Volume 1 (2001), Issue 2, Pages 69-90
doi:10.1155/S1110757X01000225

Quasi-definiteness of generalized Uvarov transforms of moment functionals

D. H. Kim and K. H. Kwon

Division of Applied Mathematics, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea

Received 11 March 2001

Abstract

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+λΣl=1 mΣk=0 ml((−1)kulk/k!)δ (k)(x − c l), where λ,ulk, and cl are constants with ci≠cj for i≠j. That is, τ is a generalized Uvarov transform of σ satisfying A(x) τ=A(x) σ, where A(x)=∏l=1m(x−cl)ml+1. We find necessary and sufficient conditions for τ to be quasi-definite. We also discuss various properties of monic orthogonal polynomial system {Rn (x)}n=0∞ relative to τ including two examples.