Given a closed subspace S of a Hilbert space H and a bounded linear operator A âˆˆ L(H) which is positive, consider the set of all A-selfadjoint projections onto S P(A,S) = {Q âˆˆ L(H) : Q2 = Q , Q(H) =â€¦ (More)

A generalization with singular weights of Moore-Penrose generalized inverses of closed range operators in Hilbert spaces is studied using the notion of compatibility of subspaces and positiveâ€¦ (More)

If H is a Hilbert space, A is a positive bounded linear operator on H and S is a closed subspace of H, the relative position between S and Aâˆ’1(SâŠ¥) establishes a notion of compatibility. We show thatâ€¦ (More)

We give conditions on a continuous and bounded function H in R2 to obtain at least two weak solutions of the mean curvature equation with Dirichlet condition for revolution surfaces with boundary,â€¦ (More)

Let H be a complex Hilbert space. We study the geometry of the space of pairs (A,E), for A a (semidefinite bounded linear) positive operator on H and E a (bounded linear) projection on H such that AEâ€¦ (More)

Let H be a complex Hilbert space. We study the relationships between the angles between closed subspaces of H, the oblique projections associated to non direct decompositions of H and a notion ofâ€¦ (More)

1 Abstract Let CR(H, K) be the set of all bounded linear operators between Hilbert spaces H, K. This paper is devoted to the study of the topological properties of CR(H, K) if certain natural metricsâ€¦ (More)

Let H be a Hilbert space, L(H) the algebra of all bounded linear operators on H and h; i A : H H ! C the bounded sesquilinear form induced by a selfadjoint A 2 L(H), h; i A = hAA; i ; ; 2 H: Given Tâ€¦ (More)

Let A be a unital C *-algebra with involution * represented in a Hilbert space H, G the group of invertible elements of A, U the unitary group of A, G s the set of invertible selfadjoint elements ofâ€¦ (More)