In this paper, we consider several questions emerging from the Beurling-Lax-Halmos Theorem, which characterizes shift-invariant subspaces of vector-valued Hardy spaces. The Theorem states that a backward subspace is model space $\mathcal{H}(\Delta) \equiv H_E^2 \ominus \Delta H_{E}^2$, for some inner function $\Delta$. Our first question calls description set $F$ in $H_E^2$ such $\mathcal{H}(\D...

We overview recent results on generalizations of the Wasserstein 2-metric, originally defined on the space of scalar probability densities, to the space of Hermitian matrices and of matrix-valued distributions, as well as some extensions of the theory to vector-valued distributions and discrete spaces (weighted graphs). Dedicated to Professor Mathukumalli Vidyasagar on his 70th birthday.

a concept of weak $f$-property for a set-valued mapping is introduced‎, ‎and then under some suitable assumptions‎, ‎which do not involve any information‎ ‎about the solution set‎, ‎the lower semicontinuity of the solution mapping to‎ ‎the parametric‎ ‎set-valued vector equilibrium-like problems are derived by using a density result and scalarization method‎, ‎where the‎ ‎constraint set $k$...