We give a unifying description of the Dirac monopole on the 2-sphere S2, of a graded monopole on a (2, 2)-supersphere S2,2 and of the BPST instanton on the 4-sphere S4, by constructing a suitable global projector p via equivariant maps. This projector determines the projective module of finite type of sections of the corresponding vector bundle. The canonical connection ∇ = p◦d is used to compu...

We define the presented dimensions for modules and rings to measure how far away a module is from having an infinite finite presentation and develop ways to compute the projective dimension of a module with a finite presented dimension and the right global dimension of a ring. We also make a comparison of the right global dimension, the weak global dimension, and the presented dimension and div...

This paper studies the incidence relation between the points and quadrics in the projective space of a symplectic vector space over a field of even order. The 2-rank of the incidence matrix is determined. This is achieved by viewing the code generated by incidence vectors as a module for the symplectic group and applying the 2-modular representation theory of this group. The radical series of t...

Let X be a projective scheme and let M and N be two coherent OX -modules. Given an integer m, we present an algorithm for computing the global extension module ExtX (M,N ). As a consequence, one may calculate the sheaf cohomology Hm(X,N ) and construct the sheaf corresponding to an element of the module ExtX(M,N ). This algorithm depends only on the computation of Gröbner bases and syzygies and...

In this paper we study totally projective QTAG-modules and the extensions of bounded QTAG-modules. In the first section we study totally projective modules M/N and M ′/N ′ where N , N ′ are isomorphic nice submodules of M and M ′ respectively. In fact the height preserving isomorphism between nice submodules is extented to the isomorphism from M onto M ′ with the help of Ulm-Kaplansky invariant...

We exhibit an example of a line bundle M on a smooth complex projective variety Y s.t. M satisfies Property Np for some p, the p-module of a minimal resolution of the ideal of the embedding of Y by M is nonzero and M does not satisfy Property Np. Let M be a very ample line bundle on a smooth complex projective variety Y and let φM : Y → P(H (Y,M)) be the map associated to M . We recall the defi...

All rings are commutative with identity and all modules are unital. The tensor product of projective (resp. flat, multiplication) modules is a projective (resp. flat, multiplication) module but not conversely. In this paper we give some conditions under which the converse is true. We also give necessary and sufficient conditions for the tensor product of faithful multiplication Dedekind (resp. ...

We describe a minimal unstable module presentation over the Steenrod algebra for the odd-primary cohomology of infinitedimensional complex projective space and apply it to obtain a minimal algebra presentation for the cohomology of the classifying space of the infinite unitary group. We also show that there is a unique Steenrod module structure on any unstable cyclic module that has dimension o...

An R-module A is called GF-regular if, for each a ∈ A and r ∈ R, there exist t ∈ R and a positive integer n such that r(n)tr(n)a = r(n)a. We proved that each unitary R-module A contains a unique maximal GF-regular submodule, which we denoted by M GF(A). Furthermore, the radical properties of A are investigated; we proved that if A is an R-module and K is a submodule of A, then MGF(K) = K∩M GF(A...