Multiple collisions of eigenvalues and singular values of matrix Gaussian field

Let X^ be a real symmetric or complex Hermitian matrix whose entries are independent Gaussian random fields. We provide the sufficient and necessary conditions such that multiple collisions of eigenvalue processes of A^ + T_ X^ T_^* occur with positive probability. In addition, for a real or complex rectangular matrix W^ with independent Gaussian random field entries, we obtain the sufficient and necessary conditions under which the probability of multiple collisions of non-trivial singular value processes of B^ + T_ W^ T_ is positive. In both cases, the size of the set of collision times is characterized via Hausdorff dimension.