Hermitian Block Toeplitz Matrices, Orthogonal Polynomials, Reproducing Kernel Pontryagin Spaces, Interpolation and Extension

A largely expository account of the theory of matrix orthogonal polynomials associated with Hermitian block Toeplitz matrices, including assorted recursions, algorithms and zero properties is prepared, using structured reproducing kernel Pontryagin spaces as a key tool. A number of closely related problems of interpolation and extension are also studied.