Let R be a semiprime ring and let F, f : R → R be (not necessarily additive) maps satisfying F (xy) = F (x)y + xf(y) for all x, y ∈ R. Suppose that there are integers m and n such that F (uv) = mF (u)F (v) + nF (v)F (u) for all u, v in some nonzero ideal I of R. Under some mild assumptions on R, we prove that there exists c ∈ C(I) such that c = (m + n)c2, nc[I, I] = 0 and F (x) = cx for all x ∈...

Necessary and sufficient conditions for an Ore extension S = R[x;σ, δ] to be a PI ring are given in the case σ is an injective endomorphism of a semiprime ring R satisfying the ACC on annihilators. Also, for an arbitrary endomorphism τ of R, a characterization of Ore extensions R[x; τ ] which are PI rings is given, provided the coefficient ring R is noetherian.

let $r$ be a commutative noetherian ring with non-zero identity, $fa$ an ideal of $r$, and $x$ an $r$--module. here, for fixed integers $s, t$ and a finite $fa$--torsion $r$--module $n$, we first study the membership of $ext^{s+t}_{r}(n, x)$ and $ext^{s}_{r}(n, h^{t}_{fa}(x))$ in the serre subcategories of the category of $r$--modules. then, we present some conditions which ensure the exi...

We study the K-theory of ring C*-algebras associated to rings of integers in global function fields with only one single infinite place. First, we compute the torsion-free part of the K-groups of these ring C*-algebras. Secondly, we show that, under a certain primeness condition, the torsion part of K-theory determines the inertia degrees at infinity of our function fields.

Derivations, Jordan derivations, as well as automorphisms and Jordan automorphisms of the algebra of triangular matrices and some class of their subalgebras have been the object of active research for a long time [1, 2, 5, 6, 9, 10]. A well-know result of Herstein [11] states that every Jordan isomorphism on a prime ring of characteristic different from 2 is either an isomorphism or an anti-iso...

This ring structure is complicated. In particular it is not the product structure. However, this way of defining the Witt vectors gives us a useful approach for how to prove things about them. Roughly speaking, to prove something about W(A) one can use the ghost map to transfer the problem to the ring A with its product structure. This works especially well if A is p-torsion free since then con...

Let X k be a smooth proper scheme over a perfect field of characteristic p and let n be a natural number. A fundamental theorem of Barry Mazur relates the Hodge numbers of X k to the action of Frobenius on the crystalline cohomology H cris (X W) of X over the Witt ring W of k, which can be viewed as a linear map 8: F*W H n cris (X W) H n cris (X W). If H n cris (X W) is torsion free, then since...

The main object of this note is to study the conormal module M and the computation of the second symbolic power ḡ of an ideal ḡ in the residue ring O/h of a polynomial ring O over a field of characteristic zero. The torsion part T (M) of M and the torsion free module M/T (M) are expressed by the primitive ideal of g relative to h. Two characterizations for M/T (M) to be free are proved. Some im...

‎let $r$ be a commutative ring with non-zero identity. ‎we describe all $c_3$‎- ‎and $c_4$-free intersection graph of non-trivial ideals of $r$ as well as $c_n$-free intersection graph when $r$ is a reduced ring. ‎also, ‎we shall describe all complete, ‎regular and $n$-claw-free intersection graphs. ‎finally, ‎we shall prove that almost all artin rings $r$ have hamiltonian intersection graphs. ...

We characterize the k -torsion freeness of module differentials order n a point hypersurface in terms singular locus corresponding local ring.