we observe some new characterizations of $n$-presented modules. using the concepts of $(n,0)$-injectivity and $(n,0)$-flatness of modules, we also present some characterizations of right $n$-coherent rings, right $n$-hereditary rings, and right $n$-regular rings.

let $alpha$ be an endomorphism and $delta$ an $alpha$-derivationof a ring $r$.  in this paper we  study the relationship between an$r$-module $m_r$ and the  general polynomial module  $m[x]$ over theskew polynomial ring $r[x;alpha,delta]$. we introduce the notionsof skew-armendariz modules and skew quasi-armendariz modules whichare generalizations of $alpha$-armendariz modules and extend thecla...

Let g be a complex finite dimensional simple Lie algebra with the root datum (Y,X, . . . ), see [Lu2]. Let Wf denote the Weyl group, R denote the root system, R+ denote the set of positive roots. Let X+ denote the set of dominant integral weights. Let h denote the Coxeter number of g. Let us fix l ∈ N, l > h. We assume that l is odd (and not divisible by 3, if g is of type G2). Let W denote the...

The purpose of this paper is to introduce some new classes of rings and modules that are closely related to the classes of almost Dedekind domains and almost Dedekind modules. We introduce the concepts of $\phi$-almost Dedekind rings and $\Phi$-almost Dedekind modules and study some properties of this classes. In this paper we get some equivalent conditions for $\phi$-almost Dedekind rings and ...

We develop the theory of a category CA which is generalisation to non-restricted g-modules famously studied by Andersen, Jantzen and Soergel for restricted g-modules, where g Lie algebra reductive group G over an algebraically closed field K characteristic p>0. Its objects are certain graded bimodules. On left, they modules Uχ associated χ∈g⁎ in standard Levi form. right, commutative Noetherian...

Let R be a commutative Noetherian ring. The k-torsionless modules are defined in [7] as a generalization of torsionless and reflexive modules, i.e., torsionless modules are 1-torsionless and reflexive modules are 2-torsionless. Some properties of torsionless, reflexive, and k-torsionless modules are investigated in this paper. It is proved that if M is an R-module such that G-dimR(M)

Let V be a simple vertex operator algebra which admits the continuous, faithful action of a compact Lie group G of automorphisms. We establish a Schur-Weyl type duality between the unitary, irreducible modules for G and the irreducible modules for V G which are contained in V where V G is the space of G-invariants of V. We also prove a concomitant Galois correspondence between vertex operator s...

Let k be an algebraically closed field of characteristic p > 0. A theorem of de Jong shows that morphisms of modules over W (k)[[t]] with Frobenius and connection structure descend from the completion of W (k)((t)). A careful reading of de Jong’s proof suggests the possibility that an analogous theorem holds for modules with only a Frobenius structure. We show that this analogue holds in one na...

Let G be a finite group and let T (G) be the abelian group of equivalence classes of endotrivial kG-modules, where k is an algebraically closed field of characteristic p. We investigate the torsion-free part TF (G) of the group T (G) and look for generators of TF (G). We describe three methods for obtaining generators. Each of them only gives partial answers to the question but we obtain more p...

Let G be a semisimple, simply connected algebraic group defined over an algebraically closed field k of positive characteristic p. Assume that p is larger than the Coxeter number of G and that the Lusztig character formula holds for regular restricted dominant weights. In this paper, we introduce two new highest weight categories C even and C reg odd , both full subcategories of the category C ...