Centralizers of generalized derivations on multilinear polynomials in prime rings

Let R be a prime ring of characteristic different from 2, with Utumi quotient ring U and extended centroid C, δ a nonzero derivation of R, G a nonzero generalized derivation of R, and f(x ₁, …, x _n ) a noncentral multilinear polynomial over C. If δ(G(f(r ₁, …, r _n ))f(r ₁, …, r _n )) = 0 for all r ₁, …, r _n ∈ R, then f(x ₁, …, x _n )² is central-valued on R. Moreover there exists a ∈ U such that G(x) = ax for all x ∈ R and δ is an inner derivation of R such that δ(a) = 0.     

On the graded identities ofM 1,1(E)

We determine theS _n ×S _m -cocharacterX _n,m of the algebraM _1,1(E) and prove that theT ₂-ideal of its graded identities is generated by the polynomialsy ₁ y ₂−y ₂ y ₁ andz ₁ z ₂ z ₃+z ₃ z ₂ z ₁.     

On the products of Nash subvarieties by spheres

We show that the product of any sphere by any compact connected component of a real algebraic variety is Nash isomorphic to a real algebraic variety, and we deduce such a result for some non-compact components, too. It follows also that the product of any sphere by any compact global Nash subvariety of is Nash isomorphic to a real algebraic variety.

     

On multiplicative (generalized)-derivations in prime and semiprime rings

Let R be a ring. A map ${F : R \rightarrow R}$ F : R → R is called a multiplicative (generalized)-derivation if F(xy) = F(x)y + xg(y) is fulfilled for all ${x, y \in R}$ x , y ∈ R where ${g : R \rightarrow R}$ g : R → R is any map (not necessarily derivation). The main objective of the present paper is to study the following situations: (i) ${F(xy) \pm xy \in Z}$ F ( xy ) ± xy ∈ Z , (ii) ${F(xy) \pm yx \in Z}$ F ( xy ) ± yx ∈ Z , (iii) ${F(x)F(y) \pm xy \in Z}$ F ( x ) F ( y ) ± xy ∈ Z and (iv) ${F(x)F(y) \pm yx \in Z}$ F ( x ) F ( y ) ± yx ∈ Z for all x, y in some appropriate subset of R. Moreover, some examples are also given.     

On the motive of certain subvarieties of fixed flags

We compute the Chow motive of certain subvarieties of the Flags manifold and show that it is an Artin motive.     

On a diophantine inequality involving prime numbers (III)

Let 1<c<11/10. In the present paper it is proved that there exists a numberN(c)>0 such that for each real numberN>N(c) the inequality is solvable in prime numbersp ₁,p ₂,p ₃, wherec ₁ is some absolute positive constant. Project supported by the National Natural Science Foundation of China (grant: 19801021) and by MCSEC