摘要:

We consider the original version of the author's example of an algebraic scheme carrying an invertible sheaf arising from no Cartier divisor.

ISSN:0092-7872    

DOI:10.1080/00927870008827181

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

We show how to lift any monomial idealJinnvariables to a saturated idealJof the same codimension inn-+ t variables. We show that I has the same graded Betti numbers asJand we show how to obtain the matrices for the resolution ofI. The cohornology oflis described. Making general choices for our lifting, we show thatlis the ideal of a reduced union of linear varieties with singularities that are "as small as possible" given the cohomological constraints. The case whereJis Artinian is the nicest. In the case of curves we obtain stick figures forl, and in the case of points we obtain certaink-configurations which we can describe in a very precise way.

ISSN:0092-7872    

DOI:10.1080/00927870008827182

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827183

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

Given a finite setX, of points in projective space for which the Hilbert function is known, a standard result says that there exists a subset of this finite set whose Hilbert function is"as big as possible"insideX. Given a finite set of points in projective space for which the minimal free resolution of its homogeneous ideal is known, what can be said about possible resolutions of ideals of subsets of this finite set? We first give a maximal rank type description of the most generic possible resolution of a subset. Then we show, via two very different kinds of counterexamples, that this generic resolution is not always achieved. However, we show that it is achieved for sets of points in projective two space: given any finite set of points in projective two space for which the minimal free resolution is known, there must exist a subset having the predicted resolution.

ISSN:0092-7872    

DOI:10.1080/00927870008827184

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

We study the deformations of restrictions toP3andP4of Tango's rank 2 bundle onP5(which exists in characteristic 2). Using this, we construct an example of a family of rank two bundles onP3(in characteristic 2) with changing α-invariant and an example of a component of the Hilbert scheme of smooth surfaces inP4which exists in characteristic 2 but not in anv other characteristic.

ISSN:0092-7872    

DOI:10.1080/00927870008827185

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827186

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

Using the data schemes from [1] we give a rigorous definition of algebraic differential equations on the complex projective space Pn. For an algebraic subvarietyS⊆Pn, we present an explicit formula for the degree of the divisor of solutions of a differential equation onSand give some examples of applications. We extend the technique and result to the real case.

ISSN:0092-7872    

DOI:10.1080/00927870008827187

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

Let (XL) be a polarized manifold with dimX=n≥3 and dim Bs |L|≤0. In this paper, we classify (X,L) withg(L) =q(X) +m and ho(L) ≥n+m.

ISSN:0092-7872    

DOI:10.1080/00927870008827188

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827189

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008827190

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor