scholarly journals On the norm of symmetrised two-sided multiplications

2003 ◽  
Vol 67 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Bojan Magajna ◽  
Aleksej Turnšek

The authors provide precise lower bounds for the completely bounded norm of the operator Ta,b: ß(H) → ß(H) defined by Ta,b (x) = axb + bxa and the injective norm of the corresponding tensor. Further, they compute the norm of the operator x ↦ a*xb + b*xa acting on the space of all conjugate-linear operators on H.

Author(s):  
B. J. Harris

SynopsisWe consider ihe differential expression M[y]: = −y″ + qy on [0, ∞) where q_∈ Lp [0, ∞) for some p ≧ 1. It is known that M, together with the boundary conditions y(0) = 0 or y′(0) = 0, defines linear operators on L2 [0, ∞). We obtain lower bounds for the spectra of these operators. Our bounds depend on the Lp norm of q_ and extend results of Everitt and Veling.


Author(s):  
B. E. Rhoades ◽  
Pali Sen

We determine the lower bounds for classes of Rhaly matrices, considered as bounded linear operators onℓp. We improve on and provide correct proofs of the results of the first author (1990).


Author(s):  
Michael F. Barnsley ◽  
Peter D. Robinson

SYNOPSISLet A be a closed linear transformation from a real Hilbert space ℋ, with symmetric inner product 〈, 〉, into itself; and let f ∈ ℋ be given such that the problem Aø = f has a solution ø ∈ D(A), the domain of A. Then bivariational upper and lower bounds on 〈g, ø〉 for any g ∈ ℋ are exhibited when there exists a positive constant a such that 〈AΦ, AΦ⊖ ≧ a2〈Φ, Φ〉 for all Φ ∈ D(A). The applicability of the theory both to Fredholm integral equations and also to time-dependent diffusion equations is demonstrated.


2010 ◽  
Vol 47 (3) ◽  
pp. 289-298 ◽  
Author(s):  
Fadime Dirik ◽  
Oktay Duman ◽  
Kamil Demirci

In the present work, using the concept of A -statistical convergence for double real sequences, we obtain a statistical approximation theorem for sequences of positive linear operators defined on the space of all real valued B -continuous functions on a compact subset of the real line. Furthermore, we display an application which shows that our new result is stronger than its classical version.


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