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Journal ArticleDOI

Shorted operators. ii

William N. Anderson, +1 more
- 01 Jan 1975 - 
- Vol. 28, Iss: 1, pp 60-71
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TLDR
In this article, the authors prove that the shorted operator exists and develop various properties, including a relation to parallel addition, including the relation between the short operator and parallel addition.
Abstract
For a positive operator A acting on a Hilbert space, the shorted operator $\mathcal{L}( A )$ is defined to be the supremum of all positive operators which are smaller than A and which have range lying in a fixed subspace S. This maximization problem arises naturally in electrical network theory. In this paper we prove that the shorted operator exists, and develop various properties, including a relation to parallel addition [Anderson and Duffin, J. Math. Anal. Appl., 11 (1969), pp. 576–594]. The basic properties of the shorted operator were developed for finite-dimensional spaces by Anderson [this Journal, 20 (1971), pp. 520–525] ; some of these theorems remain true in all Hilbert spaces, but the proofs are different.

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Citations
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References
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Book

Functional analysis

Frigyes Riesz
Book

Finite-Dimensional Vector Spaces

TL;DR: The first formal introduction to linear algebra, a branch of modern mathematics that studies vectors and vector spaces, was the Finite Dimensional Vector Spaces (FDVSP) by Halmos as discussed by the authors.
Journal ArticleDOI

On majorization, factorization, and range inclusion of operators on Hilbert space

TL;DR: In this paper, it was shown that a close relationship exists between the notions of majorization, factorization, and range inclusion for operators on a Hilbert space, and that these notions fit together to yield theorems.
Journal ArticleDOI

Series and parallel addition of matrices

TL;DR: In this paper, it was shown that the Hermitian semi-definite matrices form a commutative partially ordered semigroup under the parallel sum operation, and the norms are found to satisfy the inequality ∥ A : B ∥ ⩽ ∥ ∥ a ∥ : ∥ b ∥.