It is proved for certain graded non-commutative rings that if M and N are graded bi-modules, finitely generated from either side, then the Ext groups between M and N vanish from some step if and only if the Ext groups between N and M vanish from some step. Among the rings in question are twisted homogeneous coordinate rings of elliptic curves.

Let L be the Lie algebra of Block type over a field F of characteristic zero, defined with basis {Li,j | i, j ∈ Z} and relations [Li,j, Lk,l] = ((j + 1)k − (l + 1)i)Li+k,j+l. Then L is Z -graded. In this paper, Z -graded L-modules of the intermediate series are classified.

Fermionic-type character formulae are presented for charged irreducible modules of the graded parafermionic conformal field theory associated to the coset ôsp(1, 2)k/û(1). This is obtained by counting the weakly ordered ‘partitions’ subject to the graded Z̃k exclusion principle. The bosonic form of the characters is also presented.

The determination of the Iwahori-spherical unitary representations for split p-adic groups can be reduced to the classification of unitary representations with real infinitesimal character for associated graded Hecke algebras. We determine the unitary modules with real infinitesimal character for the graded Hecke algebra of type E6.

Definition 1. Let S be a graded ring, set X = ProjS and letM a graded S-module. We define a sheaf of modulesM ̃ on X as follows. For each p ∈ ProjS we have the local ring S(p) and the S(p)module M(p) (GRM,Definition 4). Let Γ(U,M ̃) be the set of all functions s : U −→ ∐p∈U M(p) with s(p) ∈M(p) for each p, which are locally fractions. That is, for every p ∈ U there is an open neighborhood p ∈ V ⊆...

We prove that if a positively-graded ring R is Gorenstein and the associated torsion functor has finite cohomological dimension, then the corresponding noncommutative projective scheme Tails(R) is a Gorenstein category in the sense of [10]. Moreover, under this condition, a (right) recollement relating Gorensteininjective sheaves in Tails(R) and (graded) Gorenstein-injective R-modules is given.

Graded-CTL is an extension of CTL with graded quantifiers which allow to reason about either at least or all but any number of possible futures. In this paper we show an extension of the NuSMV model-checker implementing symbolic algorithms for graded-CTL model checking. The implementation is based on the CUDD library, for BDDs and ADDs manipulation, and includes also an efficient algorithm for ...

The determination of the Iwahori-spherical unitary representations for split p-adic groups can be reduced to the classification of unitary representations with real infinitesimal character for associated graded Hecke algebras. We determine the unitary modules with real infinitesimal character for the graded Hecke algebra of type E6.

Projective resolutions of modules over a ring R are constructed starting from appropriate projective resolutions over a ring Q mapping to R. It is shown that such resolutions may be chosen to be minimal in codimension ≤ 2, but not in codimension 3. This is used to obtain minimal resolutions for essentially all modules over local (or graded) rings R with codimension ≤ 2. Explicit resolutions are...

We find that a compatible graded left-symmetric algebra structure on the Witt algebra induces an indecomposable module of the Witt algebra with 1-dimensional weight spaces by its left multiplication operators. From the classification of such modules of the Witt algebra, the compatible graded left-symmetric algebra structures on the Witt algebra are classified. All of them are simple and they in...