“…It will be one of our results that the zeros interlace, see Theorem 2.1. It is well-known that the eigenvalue correlations of the matrices M 1 and M 2 from (1.1) are determinantal with correlation kernels that can be expressed in terms of the biorthogonal polynomials and their transforms, see [2,3,9,10,14]. As an example of these relations we have that E [det(xI n − M 1 )] = p n,n (x), E [det(yI n − M 2 )] = q n,n (y), which show that the diagonal biorthogonal polynomials p n,n and q n,n can be considered as 'typical' characteristic polynomials for M 1 and M 2 , respectively.…”