We study the existence and characterization properties of compact Hermitian operators C on a Hilbert space H such that the norm of C is less or equal to that of C + D , for all the real and compact diagonals D in a fixed ...

We study some examples of minimal length curves in homogeneous spaces of B(H) under a left action of a unitary group. Recent results relate these curves with the existence of minimal (with respect to a quotient norm) ...

Let H be a separable Hilbert space, and let D(B(H) ah) be the antiHermitian bounded diagonal operators in some fixed orthonormal basis and K(H) the compact operators. We study the group of unitary operators Uk,d = {u ∈ ...

If X is the set of compact or p-Schatten operators over a complex Hilbert separable space H, we study the existence and characterization properties of Hermitian A∈X such that |||A|||≤|||A+D|||,for allD∈D(X) or equivalently ...

A pair (P,Q) of orthogonal projections in a Hilbert space H is called a Fredholm pair if QP:R(P)→R(Q)is a Fredholm operator. Let F be the set of all Fredholm pairs. A pair is called compact if P−Q is compact. Let C be the ...

A heuristic solution method to identify a predefined number of cells in raster maps optimizing both multiple intrinsic cell characteristics and cell patch compactness (Vanegas et al. in Lect. Notes Comput. Sci. 5072:389-404, ...