摘要:

In this article, we determine the automorphism groups of a family of cubic hypersurfaces generalizing those introduced in part I. Along the way, we determine all algebraic groups which containPSL2(Fq) and which lie inPGLn(C), whereq=2n± 1. This is accomplished using the classification of finite simple groups, information from the ATLAS of finite simple groups, the degrees of some complex representations of reductive groups over a finite field and techniques from Part I of this article needed to prove that the automorphism groups in question are finite.

ISSN:0092-7872    

DOI:10.1080/00927879408824967

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

摘要:

The present paper is the first of four which will develop a universal Existence Theorem for orbifolds. Given a category C, ultimately we find a categorical hypothesis under which C embeds into a larger category which contains quotients by finite group actions.To define a fundamental group for algebraic geometry, Grothendieck reformulated the topological invariant in terms of algebra and small cat­egories. Different concerns require the present author to revise this ap­proach, and to give a universal format for Galois covers. A complete theory of Galois correspondences and profinite fundamental groups is de­veloped for any category with a suitable notion of connectedness. The new formulation avoids base points and fiber functors.

ISSN:0092-7872    

DOI:10.1080/00927879408824968

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

摘要:

This paper is second in a quartology which develops a universal Existence Theorem for orbifolds. In this work, we adapt an existing, universal, construction to the problem. We prove a formal theorem which states that, under a certain hypothesis, a category can be expanded to include new quotients by finite group actions.

ISSN:0092-7872    

DOI:10.1080/00927879408824969

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824970

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824971

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824972

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824973

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927879408824974

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

摘要:

Relationships between the structure of a Lie algebra and that of its lattice of ideals is studied for those Lie algebras whose ideal lattice is very close to that of an almost-abelian Lie algebra. It is shown here that if the base field is algebraically closed, finite or the real one, for any n ≥3 the only solvable Lie algebra whose lattice of ideals is isomorphic to that of the (n+l)-dimensional almost-abelian Lie algebra is itself.

ISSN:0092-7872    

DOI:10.1080/00927879408824975

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor

摘要:

n this paper we present a new algebraic characterization of (almost-)crys-tallographic groups. In fact we prove that a virtually abelian (resp. nilpotent) group E is crystallographic (resp. almost-crystallographic) if and only if E has no finite normal subgroups. Thereafter, we investigate more general groups sharing this property and refer to them as the almost-torsion free groups. We show that a virtually polycyclic group Y is almost-torsion free if and only if T is (almost-crystallographic)-by-crystallographic. Thereafter, we take a closer look at the topological properties of almost-torsion free groups.

ISSN:0092-7872    

DOI:10.1080/00927879408824976

出版商:Gordon and Breach Science Publishers Ltd.    

年代:1994

数据来源: Taylor