ISSN:0092-7872    

DOI:10.1080/00927879808826190

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

摘要:

Let X be a smooth protective curve of genus g ≥2. Here we study the existence of stable vector bundles, E, on X with a filtration with suitable numerical invariants. Sometimes, we show that the set of all such bundles is parametrized by an irreducible variety and that for certain numerical data one such family is in the closure of another such family. Tools: dimensional computations, elementary transformations and known results on generic stable bundles.

ISSN:0092-7872    

DOI:10.1080/00927878808826191

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879808826192

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

摘要:

We consider graded Clifford algebras onngenerators in the spirit of Artin, Tate and Van den Bergh’s non-commutative algebraic geometry. We give an algorithm for counting the point modules over such an algebra, and prove that a generic graded Clifford algebra on four generators has defining relations which are determined by their zero locus in P3× P3Furthermore, we find a 1-parameter family of iterated Ore extensions on four generators which are deformations of a graded Clifford algebra such that the generic member has precisely one point module and a 1-dimensional family of line modules.

ISSN:0092-7872    

DOI:10.1080/00927879808826193

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

摘要:

For an arithmetically Cohen–Macaulay subscheme of projective space, there is a well-known bound for the highest degree of a minimal generator for the defining ideal of the subscheme, in terms of the Hilbert function. We prove a natural extension of this bound for arbitrary locally Cohen–Macaulay subschemes. We then specialize to curves inP3, and show that the curves whose defining ideals have generators of maximal degree satisfy an interesting cobomological property. The even liaison classes possessing such curves are characterized, and we show that within an even liaison class, all curves with the property satisfy a strong Lazarsfeld–Rao structure theorem. This allows us to give relatively complete conditions for when a liaison class contains curves whose ideals have maximal degree generators, and where within the liaison class they occur.

ISSN:0092-7872    

DOI:10.1080/00927879808826194

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

摘要:

In this paper we show that the braid groupsBnand the symmetric automorphism groupsH(n) of the free groupFn,n= 3,4 act in a non-linear way on an algebra with straightening law (ordinal Hodge algebra). We indicate various properties of these rings.

ISSN:0092-7872    

DOI:10.1080/00927879808826195

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

摘要:

We deal with the congruence lattices of regular semigroups with inverse transversals. We give descriptions for the relationsT,TrTlUandVon the congruence lattice of semigroups of this kind, present expressions for the extremal values in the classes of these relations.

ISSN:0092-7872    

DOI:10.1080/00927879808826196

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879808826197

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879808826198

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879808826199

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1998

数据来源: Taylor