Sobolev orthogonal polynomials and spectral differential equations

I. H. Jung, K. H. Kwon, D. W. Lee, L. L. Littlejohn
1995 Transactions of the American Mathematical Society  
We find necessary and sufficient conditions for a spectral differential equation N LN[y](x) = 52t¡(x)yW(x) = kny(x) (-1 to have Sobolev orthogonal polynomials of solutions, which are orthogonal relative to the Sobolev (pseudo-) inner product c t (P ,q)= / Pqdn + I p'q'du, Jr Jr where d/i and dv are signed Borel measures having finite moments. This result generalizes a result by H. L. Krall, which handles the case when dv = 0 .
doi:10.1090/s0002-9947-1995-1308015-9 fatcat:m53cmkewf5fixpncfrzp42ofeu