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111.
112.
113.
Chandrasekhar Chatterjee Sunandan Gangopadhyay Arindam Ghosh Hazra Saurav Samanta 《International Journal of Theoretical Physics》2008,47(9):2372-2381
The appearance of non(anti)commutativity in superstring theory, satisfying the Neveu-Schwarz boundary conditions is discussed
in this paper. Both an open free superstring and also one moving in a background antisymmetric tensor field are analyzed to
illustrate the point that string non(anti)commutativity is a consequence of the nontrivial boundary conditions. The method
used here is quite different from several other approaches where boundary conditions were treated as constraints. An interesting
observation of this study is that, one requires that the bosonic sector satisfies Dirichlet boundary conditions at one end
and Neumann at the other in the case of the bosonic variables X
μ
being antiperiodic. The non(anti)commutative structures derived in this paper also leads to the closure of the super constraint
algebra which is essential for the internal consistency of our analysis. 相似文献
114.
B. Kuzma 《Journal of Mathematical Analysis and Applications》2005,304(1):13-21
Additive bijections , which compress the spectrum between two unital, standard operator algebras, are characterized. Applications to local approximate (anti)multiplications are also given. 相似文献
115.
Let be a maximal atomic nest on Hilbert space H and denote the associated nest algebra. We prove that a weakly continuous and
surjective linear map preserves the closure of numerical
range if and only if there exists a unitary operator such that for every or for every ,
where denotes the transpose of T relative to an arbitrary but fixed base
of H. As applications, we get the characterizations of the numerical range
or numerical radius preservers on . The surjective linear maps on the
diagonal algebras of atomic nest algebras preserving the closure of numerical
range or preserving the numerical range (radius) are also characterized.
Submitted: January 3, 2001?Revised: December 2, 2001 相似文献
116.
We give three kinds of characterizations of the commutativity of C- algebras. The first is the one from operator monotone property of functions regarded as the nonlinear version of Stinespring theorem, the second one is the characterization of commutativity of local type from expansion formulae of related functions and the third one is of global type from multiple positivity of those nonlinear positive maps induced from functions.
117.
118.
Jan Stochel 《Proceedings of the American Mathematical Society》1998,126(2):431-440
It is shown that an -tuple of bounded linear operators on a complex Hilbert space, which is positive definite in the sense of Halmos, must be commutative. Some generalizations of this result to the case of pairs of unbounded operators are obtained.
119.
120.
Firstly,the commutativity of rings is investigated in this paper.Let R be a ring with identity.Then we obtain the following commutativity conditions: (1) if for each x ∈ R\N(R) and each y ∈ R,(xy)k =xkyk for k =m,m + 1,n,n + 1,where m and n are relatively prime positive integers,then R is commutative;(2) if for each x ∈ R\J(R) and each y ∈ R,(xy)k =ykxk for k =m,m+ 1,m+2,where m is a positive integer,then R is commutative.Secondly,generalized 2-CN rings,a kind of ring being commutative to some extent,are investigated.Some relations between generalized 2-CN rings and other kinds of rings,such as reduced rings,regular rings,2-good rings,and weakly Abel rings,are presented. 相似文献