We study the differentiable structure and the homotopy type of some spaces related to the Grassmannian of closed linear subspaces of an infinite dimensional Hilbert space, such as the space of Fredholm pairs, the Grassmannian of compact perturbations of a given space, and the essential Grassmannians. We define a determinant bundle over the space of Fredholm pairs. We lift the composition of Fre...

In the case of linear operator property P(B, k) was introduced by M.A. Kaashoek. this paper, we characterize essentially semi regular relation in terms k). After that and as an application result give some connection between relations. Further, will supplementary conditions on to be Fredholm. Then, analyze stability class relations under small perturbations Riesz operators. Finally, study prope...

We provide sufficient conditions for vector-valued Fredholm integral operators and their commonly used spatial discretizations to be positive in terms of an order relation induced by a corresponding cone. It turns out that reasonable Nyström methods preserve positivity. Among the projection methods, persistence is obtained simplest ones based on polynomial, piecewise linear or specific cubic in...

In this paper, the Fredholm properties of some Toeplitz operators on Dirichlet spaces be discussed, and the essential spectra of Toeplitz operators with symbols in C 1 or H ∞ 1 + C 1 be computed.