Results 41 to 50 of about 306 (62)

Counterexamples Related to Commutators of Unbounded Operators [PDF]

arXiv, 2018
The present paper is exclusively devoted to counterexamples about commutators and self commutators of unbounded operators on a Hilbert space. As a bonus, we provide a simpler counterexample than McIntosh's famous example obtained some while ago.
arxiv  

On local properties of Hochschild cohomology of a C$^*$- algebra [PDF]

, 2007
Let $A$ be a C$^*$-algebra, and let $X$ be a Banach $A$-bimodule. B. E. Johnson showed that local derivations from $A$ into $X$ are derivations. We extend this concept of locality to the higher cohomology of a $C^*$-algebra %for $n$-cocycles from $A^{(n)}$ into $X$ and show that, for every $n\in \N$, bounded local $n$-cocycles from $A^{(n)}$ into $X ...
arxiv   +1 more source

Nilpotent perturbations of m-isometric and m-symmetric tensor products of commuting d-tuples of operators

Demonstratio Mathematica
If T1{{\mathbb{T}}}_{1} and T2{{\mathbb{T}}}_{2} are commuting dd-tuples of Hilbert space operators in B(ℋ)dB{\left({\mathcal{ {\mathcal H} }})}^{d} such that (T1*⊗I+I⊗T2*,T1⊗I+I⊗T2)\left({{\mathbb{T}}}_{1}^{* }\otimes I+I\otimes {{\mathbb{T}}}_{2}^{* },{
Duggal Bhagwati Prashad, Kim In Hyoun
doaj   +1 more source

Bloom-type two-weight inequalities for commutators of maximal functions

Analysis and Geometry in Metric Spaces
We study Bloom-type two-weight inequalities for commutators of the Hardy-Littlewood maximal function and sharp maximal function. Some necessary and sufficient conditions are given to characterize the two-weight inequalities for such commutators.
Zhang Pu, Fan Di
doaj   +1 more source

Spectral equality for $C_0$ semigroups [PDF]

arXiv, 2016
In this paper, we give conditions for which the $C_0$ semigroups satisfies spectral equality for semiregular, essentially semiregular and semi-Fredholm spectrum. Also, we establish the spectral inclusion for B-Fredholm spectrum of a $C_0$ semigroups.
arxiv  

Connes-amenability and normal, virtual diagonals for measure algebras, I [PDF]

J. London Math. Soc. 67 (2003), 643-656, 2001
We prove that the measure algebra $M(G)$ of a locally compact group $G$ is Connes-amenable if and only if $G$ is amenable.
arxiv  

About instability in an elastic Cosserat body with pores

Analele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica
This article is centered on the study of the isotropic, porous Cosserat elastic media, realized by means of a parallel with the media of the same type, but anisotropic, by following the rewriting in a new form of the equations that govern this theory ...
Codarcea-Munteanu L., Marin M., Abouelregal A. E.   +2 more
doaj   +1 more source

Connes-amenability and normal, virtual diagonals for measure algebras, II [PDF]

Bull. Austral. Math. Soc. 68 (2003), 325-328, 2001
We prove that the following are equivalent for a locally compact group $G$: (i) $G$ is amenable; (ii) $M(G)$ is Connes-amenable; (iii) $M(G)$ has a normal, virtual diagonal.
arxiv  

Norms and CB norms of Jordan elementary operators [PDF]

arXiv, 2003
We establish lower bounds for norms and CB-norms of elementary operators on B(H). Our main result concerns the operator Tx = axb + bxa and we show its norm is at least the product of the norms of a and b, proving a conjecture of M. Mathieu. We also establish some other results and formulae for the CB norm and norm of such T for special cases.
arxiv  

Some conditions under which Jordan derivations are zero

Journal of Taibah University for Science, 2017
In the current article, we obtain the following results: Let A be an algebra and P be a semi-prime ideal of A. Suppose that d:A→(A/P) is a Jordan derivation such that dim{d(a)|a∈A}≤1. If d(P)={0}, then d is zero.
Z. Jokar, A. Hosseini, A. Niknam
doaj