Darboux transformations of Jacobi matrices and Pad\'e approximation

Let J be a monic Jacobi matrix associated with the Cauchy transform F of a probability measure. We construct a pair of the lower and upper triangular block matrices L and U such that J=LU and the matrix J_c=UL is a monic generalized Jacobi matrix associated with the function F_c(z)=zF(z)+1. It turns out that the Christoffel transformation J_c of a bounded monic Jacobi matrix J can be unbounded. This phenomenon is shown to be related to the effect of accumulating at infinity of the poles of the Pad\'e approximants of the function F_c although F_c is holomorphic at infinity. The case of the UL-factorization of J is considered as well.Comment: 28 pages (some typos are corrected

The present and future of development projects and strategies to achieve sustainability

행사명 : Korea's global ODA forum for sustainable agricultural developmen

Exil als Heimat : Deutsche Juden in New York: Beispiele intellektueller Emigrationsbewältigung.

Radio program with excerpts from interviews with German Jews in New York, describing how they mastered the situation with which they were confronted upon their immigration to America.Broadcast on November 27, 1974 and January 15, 1975, by Deutschlandfunk