In this article we consider the sequences of sample and population covariance operators for a sequence of arrays of Hilbertian random elements. Then under the assumptions that sequences of the covariance operators norm are uniformly bounded and the sequences of the principal component scores are uniformly sumable, we prove that the convergence of the sequences of covariance operators would impl...

Let X be a Banach space and T be a bounded linear operator from X to itself (T ∈ B(X)). An operator S ∈ B(X) is a generalised inverse of T if TST = T . In this paper we look at the Jörgens algebra, an algebra of operators on a dual system, and characterise when an operator in that algebra has a generalised inverse that is also in the algebra. This result is then applied to bounded inner product...

Motivated by problems in the spectral theory of linear operators the authors previously introduced a new concept of variation for functions defined on a nonempty compact subset of the plane. In this paper we examine the algebras of functions of bounded variation one obtains from these new definitions for the case where the underlying compact set is either a rectangle or the unit circle, and com...

In this paper we show how to produce a large number of representations of a graph C*-algebra in the space of the bounded linear operators in L2(X,μ). These representations are very concrete and, in the case of graphs that satisfy condition (K), we use our techniques to realize the associated graph C*-algebra as a subalgebra of the bounded operators in L2(R). We also show how to describe some Pe...

Let be a C∗-algebra with identity 1, and let s( ) denote the set of all states on . For p,q,r ∈ [1,∞), denote by r( ) the set of all infinite matrices A= [ajk]j,k=1 over such that the matrix (φ[A[2]]) [r] := [(φ(ajkajk))]j,k=1 defines a bounded linear operator from p to q for all φ∈ s( ). Then r( ) is a Banach algebra with the Schur product operation and norm ‖A‖ = sup{‖(φ[A[2]])‖ : φ∈ s( )}. A...

We prove that for a right linear bounded normal operator on a quaternionic Hilbert space (quaternionic bounded normal operator) the norm and the numerical radius are equal. As a consequence of this result we give a new proof of the known fact that a non zero quaternionic compact normal operator has a non zero right eigenvalue. Using this we give a new proof of the spectral theorem for quaternio...

Let X be a Banach space and T be a bounded linear operator from X to itself (T ∈ B(X).) An operator D ∈ B(X) is a Drazin inverse of T if TD = DT , D = TD and T k = T D for some nonnegative integer k. In this paper we look at the Jörgens algebra, an algebra of operators on a dual system, and characterise when an operator in that algebra has a Drazin inverse that is also in the algebra. This resu...

Let q ≥ 1 be an integer. Given M samples of a smooth function of q variables, 2π–periodic in each variable, we consider the problem of constructing a q–variate trigonometric polynomial of spherical degree O(M) which interpolates the given data, remains bounded (independent of M) on [−π, π], and converges to the function at an optimal rate on the set where the data becomes dense. We prove that t...

It is proved that bounded linear operators on Banach spaces of “cadlag” functions are measurable with respect to the Borel σ-algebra associated with the Skorokhod topology.

The Bishop-Phelps theorem [1] states that for any Banach space X, the set of norm attaining linear bounded functionals is dense in X ′, the dual space of X. Since then, the study of norm attaining functions has attracted the attention of many authors. Lindenstrauss showed in [2] that there is no Bishop-Phelps theorem for linear bounded operators. Nevertheless, he proved that the set of bounded ...