Deficiency Indices of Block Jacobi Matrices: Survey
Viktoriya Sergeevna Budyka, Mark Mikhailovich Malamud, K. Mirzoev · Contemporary Mathematics Fundamental Directions · 2021
The paper is a survey and concerns with infinite symmetric block Jacobi matrices J with mm-matrix entries. We discuss several results on general block Jacobi matrices to be either self-adjoint or have maximal as well as intermediate deficiency indices. We also discuss several conditions for J to have discrete spectrum.