Uniqueness and independence of submatrices in solutions of matrix equations.
Uniqueness of the operator attaining
Unitary automorphisms of the space of Toeplitz-plus-Hankel matrices
Our motivation was a paper of 1991 indicating three special unitary matrices that map Hermitian Toeplitz matrices by similarity into real Toeplitz-plus-Hankel matrices. Generalizing this result, we give a complete description of unitary similarity automorphisms of the space of Toeplitz-plus-Hankel matrices.
Unitary completions of complex symmetric and skew symmetric matrices.
Unitary similarity of algebras generated by pairs of orthoprojectors.
Unitary similarity of projectors.
Universal and nonuniversal dynamical conductivity in small metallic grains: an ambivalent role of T-invariance at finite frequency.
Universal bounds for matrix semigroups
We show that any compact semigroup of n × n matrices is similar to a semigroup bounded by √n. We give examples to show that this bound is best possible and consider the effect of the minimal rank of matrices in the semigroup on this bound.
Universal bounds for positive matrix semigroups
We show that any compact semigroup of positive n × n matrices is similar (via a positive diagonal similarity) to a semigroup bounded by √n. We give examples to show this bound is best possible. We also consider the effect of additional conditions on the semigroup and obtain improved bounds in some cases.
Universal factorization equalities over generalized quaternion algebras.
Universality for certain hermitian Wigner matrices under weak moment conditions
We study the universality of the local eigenvalue statistics of Gaussian divisible Hermitian Wigner matrices. These random matrices are obtained by adding an independent GUE matrix to an Hermitian random matrix with independent elements, a Wigner matrix. We prove that Tracy–Widom universality holds at the edge in this class of random matrices under the optimal moment condition that there is a uniform bound on the fourth moment of the matrix elements. Furthermore, we show that universality holds...
Universality in the random matrix spectra in the regime of weak non-hermiticity
Universally optimal matrices and field independence of the minimum rank of a graph.
Untersuchungen über quadratische Formen in Körpern der Charakteristik 2.
Upon the generalised inverse of a formal power series with vector valued coefficients
Upper bound for the non-maximal eigenvalues of irreducible nonnegative matrices
We present a lower and an upper bound for the second smallest eigenvalue of Laplacian matrices in terms of the averaged minimal cut of weighted graphs. This is used to obtain an upper bound for the real parts of the non-maximal eigenvalues of irreducible nonnegative matrices. The result can be applied to Markov chains.
Upper bounds for the abscissa of stability of a stable matrix
Upper bounds for the best normal approximation.
Upper bounds on certain functionals defined on groups of linear operators.
Upper bounds on the solution of coupled algebraic Riccati equation.