The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Xiaofei Qi - One of the best experts on this subject based on the ideXlab platform.
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strong skew Commutativity preserving maps on von neumann algebras
Journal of Mathematical Analysis and Applications, 2013Co-Authors: Xiaofei QiAbstract:Abstract Let M be a von Neumann algebra without central summands of type I 1 . Assume that Φ : M → M is a surjective map. It is shown that Φ is strong skew Commutativity preserving (that is, satisfies Φ ( A ) Φ ( B ) − Φ ( B ) Φ ( A ) ∗ = A B − B A ∗ for all A , B ∈ M ) if and only if there exists some self-adjoint element Z in the center of M with Z 2 = I such that Φ ( A ) = Z A for all A ∈ M . The strong skew Commutativity preserving maps on prime involution rings and prime involution algebras are also characterized.
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nonlinear strong Commutativity preserving maps on prime rings
Communications in Algebra, 2010Co-Authors: Xiaofei QiAbstract:Let 𝒜 be a unital prime ring containing a nontrivial idempotent P. Assume that Φ: 𝒜 → 𝒜 is a nonlinear surjective map. It is shown that Φ preserves strong Commutativity if and only if Φ has the form Φ(A) = αA + f(A) for all A ∈ 𝒜, where α ∈ {1, −1} and f is a map from 𝒜 into 𝒵(𝒜). As an application, a characterization of nonlinear surjective strong Commutativity preserving maps on factor von Neumann algebras is obtained.
Mohamad Nagy Daif - One of the best experts on this subject based on the ideXlab platform.
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on Commutativity and strong Commutativity preserving maps
Canadian Mathematical Bulletin, 1994Co-Authors: Howard E. Bell, Mohamad Nagy DaifAbstract:If R is a ring and S ⊆ R , a mapping f:R —> R is called strong Commutativity- preserving (scp) on S if [x, y] = [f(x),f(y)] for all x,y € S . We investigate Commutativity in prime and semiprime rings admitting a derivation or an endomorphism which is scp on a nonzero right ideal.
H. Richy - One of the best experts on this subject based on the ideXlab platform.
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Optimistic multi-level concurrency control for nested typed objects
Proceedings. PARBASE-90: International Conference on Databases Parallel Architectures and Their Applications, 1990Co-Authors: M. Cart, J. Ferrie, H. RichyAbstract:The authors propose an optimistic multilevel method that also exploits Commutativity of typed operations in order to enhance concurrency. One of the main advantages of this method is that it makes it possible to take Commutativity depending upon return values into account. A bank-transaction example illustrating the proposed approach is presented.
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An optimistic multi-level concurrency control for nested typed objects
Twenty-Third Annual Hawaii International Conference on System Sciences, 1990Co-Authors: M. Cart, J. Ferrie, H. RichyAbstract:The authors present a transaction model adapted to an object-oriented environment and capable of taking the semantics of objects and operations into account. They also describe a multilevel concurrency control fitted to this model. The main advantage, compared to locking methods, of this optimistic method which uses timestamps intervals is that it exploits conditional Commutativity, depending upon return values. Therefore, it is particularly well suited to situations where this kind of Commutativity is frequent, especially when operations last long. Nevertheless, like any optimistic method, it is efficient only if conflicts are rare. In the cases where conflicts are frequent but essentially caused by some well-identified operations, a possible approach would be to consider letting the method coexist, at any level, with a method using typed locks (mixed concurrency control).
Howard E. Bell - One of the best experts on this subject based on the ideXlab platform.
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generalized derivations with Commutativity and anti Commutativity conditions
Mathematical journal of Okayama University, 2007Co-Authors: Howard E. Bell, Nadeem Ur RehmanAbstract:1. IntroductionLet R be an associative ring with center Z = Z(R). For each x;y 2 Rdenote the commutator xy yx by [x;y] and the anti-commutator xy +yxby xy. Recall that a ring R is prime if for any a;b 2 R, aRb = f0g impliesthat a = 0 or b = 0. An additive mapping d : R ! R is called a derivationif d(xy) = d(x)y +xd(y) for all x;y 2 R. In particular, for xed a 2 R, themapping I
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Almost-Commutativity in Rings
Acta Mathematica Hungarica, 2002Co-Authors: Howard E. Bell, A. A. KleinAbstract:A subset X of the ring \(R\) is called almost commutative if \(X\backslash C_R \left( a \right)\) is finite for all \(a \in X\). We study Commutativity in rings in which certain infinite sets of zero divisors are almost commutative.
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on Commutativity and strong Commutativity preserving maps
Canadian Mathematical Bulletin, 1994Co-Authors: Howard E. Bell, Mohamad Nagy DaifAbstract:If R is a ring and S ⊆ R , a mapping f:R —> R is called strong Commutativity- preserving (scp) on S if [x, y] = [f(x),f(y)] for all x,y € S . We investigate Commutativity in prime and semiprime rings admitting a derivation or an endomorphism which is scp on a nonzero right ideal.
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ON PSEUDO-COMMUTATMTY AND Commutativity IN RINGS
Quaestiones Mathematicae, 1994Co-Authors: Howard E. BellAbstract:Abstract A ring R is called pseudo-commutative if for each x,y e R there exists an integer n = n(x, y) for which xy = nyx. We first show that a generalization of a Commutativity condition of Chacron and Thierrin implies pseudo-Commutativity in rings; we then study pseudo-Commutativity and Commutativity in rings with constraints of the form xy = σkiyixi, where the ki are integers.
M. Cart - One of the best experts on this subject based on the ideXlab platform.
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Optimistic multi-level concurrency control for nested typed objects
Proceedings. PARBASE-90: International Conference on Databases Parallel Architectures and Their Applications, 1990Co-Authors: M. Cart, J. Ferrie, H. RichyAbstract:The authors propose an optimistic multilevel method that also exploits Commutativity of typed operations in order to enhance concurrency. One of the main advantages of this method is that it makes it possible to take Commutativity depending upon return values into account. A bank-transaction example illustrating the proposed approach is presented.
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An optimistic multi-level concurrency control for nested typed objects
Twenty-Third Annual Hawaii International Conference on System Sciences, 1990Co-Authors: M. Cart, J. Ferrie, H. RichyAbstract:The authors present a transaction model adapted to an object-oriented environment and capable of taking the semantics of objects and operations into account. They also describe a multilevel concurrency control fitted to this model. The main advantage, compared to locking methods, of this optimistic method which uses timestamps intervals is that it exploits conditional Commutativity, depending upon return values. Therefore, it is particularly well suited to situations where this kind of Commutativity is frequent, especially when operations last long. Nevertheless, like any optimistic method, it is efficient only if conflicts are rare. In the cases where conflicts are frequent but essentially caused by some well-identified operations, a possible approach would be to consider letting the method coexist, at any level, with a method using typed locks (mixed concurrency control).
