摘要:

In this paper we consider questions connected with the problem of rigidity of rings for the class of finite-rank torsion-free rings (A ring is called rigid, if it has only trivial endomorphisms). We study strongly rigid and I-rigid rings [3] (A ring R is called strongly rigid, if any ring quasi-isomorphic to R is rigid). The main results of this paper are the characterization of strongly rigid rings and the establishment of relations between strongly rigid and I-rigid rings. It is shown that the verification of strong rigidity of the ring reduces to testing the rigidity of some field of algebraic numbers over its subfield. This gives rise to examples of non-trivial strongly rigid rings.

ISSN:0092-7872    

DOI:10.1080/00927879408824939

出版商:Marcel Dekker, Inc.    

年代:1994

数据来源: Taylor

摘要:

We study generic quadric sections of irreducible space curves. Suitable examples help to understanding the substantial differences of behaviour with respect to generic plane sections of irreducible curves. For instance we produce an example of points on a smooth quadric in strong uniform position whose Hilbert function cannot be as the one of a generic quadric section of any irreducible curve. In order to try to find all possible Hilbert functions of generic quadric sections of irreducible curves we characterize sequences of positive integers which are the first difference of the Hilbert funtions of generic quadric sections of ACM curves and then of maximal rank Buchsbaum curves.

ISSN:0092-7872    

DOI:10.1080/00927879408824940

出版商:Marcel Dekker, Inc.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824941

出版商:Marcel Dekker, Inc.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824942

出版商:Marcel Dekker, Inc.    

年代:1994

数据来源: Taylor

摘要:

Let M be a finitely generated module over a semi-local ring R with Jacobson radical J. If M is complete in the J-adic metric then, given a decreasing sequenceof nonempty closed subsets of M with intersection C0and a natural number n, necessarily CiC0+JnM for large i. This property is equivalent to the completeness of M in the J-adic metric, as well as to the completeness in the HausdorfF metric of the space of nonempty closed subsets of M. In general, the completion in the Hausdorff metric of the submodule lattice is isomorphic to the submodule lattice of the completion of the module in the J-adic metric. This extends submodule-theoretic results for complete modules to modules for which the submodule lattice is complete

ISSN:0092-7872    

DOI:10.1080/00927879408824943

出版商:Marcel Dekker, Inc.    

年代:1994

数据来源: Taylor

摘要:

We prove that the Cup product and the Lie bracket of Hochschild cohomology are graded products with respect to the decomposition.

ISSN:0092-7872    

DOI:10.1080/00927879408824944

出版商:Marcel Dekker, Inc.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824918

出版商:Marcel Dekker, Inc.    

年代:1994

数据来源: Taylor