Results 21 to 30 of about 579 (72)
International Journal of Mathematics and Mathematical Sciences, Volume 2004, Issue 53, Page 2821-2834, 2004., 2004 We extend the Putnam‐Fuglede theorem and the second‐degree Putnam‐Fuglede theorem to the nonnormal operators and to an elementary operator under perturbation by quasinilpotents. Some asymptotic results are also given.
Yin Chen
wiley +1 more source
The algebraic size of the family of injective operators
Open Mathematics, 2017 In this paper, a criterion for the existence of large linear algebras consisting, except for zero, of one-to-one operators on an infinite dimensional Banach space is provided. As a consequence, it is shown that every separable infinite dimensional Banach
Bernal-González Luis
doaj +1 more source
Joint numerical ranges: recent advances and applications minicourse by V. Müller and Yu. Tomilov
Concrete Operators, 2020 We present a survey of some recent results concerning joint numerical ranges of n-tuples of Hilbert space operators, accompanied with several new observations and remarks.
Müller V., Tomilov Yu.
doaj +1 more source
Ill‐posed equations with transformed argument
Abstract and Applied Analysis, Volume 2003, Issue 13, Page 785-791, 2003., 2003 We discuss the operator transforming the argument of a function in the L2‐setting. Here this operator is unbounded and closed. For the approximate solution of ill‐posed equations with closed operators, we present a new view on the Tikhonov regularization.
Simone Gramsch, Eberhard Schock
wiley +1 more source
A note on best approximation and invertibility of operators on uniformly convex Banach spaces
International Journal of Mathematics and Mathematical Sciences, Volume 14, Issue 3, Page 611-614, 1991., 1991 It is shown that if X is a uniformly convex Banach space and S a bounded linear operator on X for which ‖I − S‖ = 1, then S is invertible if and only if . From this it follows that if S is invertible on X then either (i) dist(I, [S]) < 1, or (ii) 0 is the unique best approximation to I from [S], a natural (partial) converse to the well‐known sufficient
James R. Holub
wiley +1 more source
Selfadjoint operators, normal operators, and characterizations
Operators and Matrices, 2019 Let B(H) be the C∗ -algebra of all bounded linear operators acting on a complex separable Hilbert space H . We shall show that: 1. The class of all selfadjoint operators in B(H) multiplied by scalars is characterized by ∀X ∈ B(H), ∥∥S2X +XS2∥∥ 2‖SXS ...
A. Seddik
semanticscholar +1 more source
Oblique projections and frames [PDF]
, 2006 We characterize those frames on a Hilbert space H which can be represented as the image of an orthonormal basis by an oblique projection defined on an extension K of H.
Antezana, Jorge Abel +3 more
core +2 more sources
On diagonalizable operators in Minkowski spaces with the Lipschitz property [PDF]
, 2010 A real semi-inner-product space is a real vector space $\M$ equipped with a function $[.,.] : \M \times \M \to \Re$ which is linear in its first variable, strictly positive and satisfies the Schwartz inequality. It is well-known that the function $||x|| =
Dragomir +9 more
core +2 more sources
COMMUTING TRACES ON INVERTIBLE AND SINGULAR OPERATORS
, 2015 Let m 1 be a natural number, and let B(H) be the Banach space of all bounded operators from a infinite dimensional separable complex (real) Hilbert space H to itself. We describe traces of m -additive maps G : B(H)m → B(H) such that [G(T, . . . ,T ),T ] =
W. Franca
semanticscholar +1 more source
Effective construction of a class of positive operators in Hilbert space, which do not admit triangular factorization [PDF]
, 2010 A class of non-factorable positive operators is constructed. As a result, pure existence theorems in the well-known problems by Ringrose, Kadison and Singer are substituted by concrete ...
Bateman +23 more
core +2 more sources