ISSN:0092-7872    

DOI:10.1080/00927870008826921

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

We show that up to a translation each automorphism of the derived categoryDbXof coherent sheaves on a weighted projective line X, equiv-alently of the derived categoryDbAof finite dimensional modules over a derived canonical algebraA, is composed of tubular mutations and automorphisms of X. In the case of genus one this implies that the automorphism group is a semi-direct product of the braid group on three strands by a finite group.

ISSN:0092-7872    

DOI:10.1080/00927870008826922

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

LetAbe a multiplier Hopf algebra which acts on an algebraR. In this paper we study semi-invariants of this action. This idea has proved interesting in the case thatAis a Hopf algebra.

ISSN:0092-7872    

DOI:10.1080/00927870008826923

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

The aim of this paper is to count subgroups of a given index in the fundamental group of an orientableS1-bundle over a compact surface. The number of subgroups of indexnturns out to be independent of the orientability of the base surface 𝔣, closed or bordered, and is expressed as a linear combination of the numbers of surface subgroups of indicesm = n/ll∣n. For a closed base surface of characteristic χ the respective coefficients are equal tol–χm+2or vanish depending onl,nand the Euler number of theS1-bundle.

ISSN:0092-7872    

DOI:10.1080/00927870008826924

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008826925

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

In this work we study the topologies of the fibres of some families of complex polynomial functions with isolated critical points. We consider polynomials with some transversality conditions at infinity and compute explicitly its global Milnor number μ(f). the invariant λ(f) and therefore the Euler characteristic of its generic fibre. We show that under some mild ransversality condition (transversal at infinity) the behavior offat infinity is good and the topology of the generic fibre is determined by the two homogeneous parts of higher degree offFinally we study families of polynomials, called two-term polynomials. This polynomials may have atypical values at infinity. Given such a two-term polynomialfwe characterize its atypical values by some invariants off. These polynomials are a source of interesting examples.

ISSN:0092-7872    

DOI:10.1080/00927870008826926

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

Absolutely irreducible representations of finite groups of exceptional Lie types in defining characteristic whose images contain matrices with simple spectra are determined. The term ”simple spectrum“ means that each eigenvalue has multiplicity 1. The similar question for the classical finite groups has been solved in the authors' previous paper [Comm. in Algebra 26 (1998), no 3, 863-888] where one can find general comments to the problem. For dimensions ≥ 100 all absolutely irreducible representations of finite groups of Lie type in defining characteristic containing matrices with simple spectra are tabulated.

ISSN:0092-7872    

DOI:10.1080/00927870008826927

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

We prove a conjecture of Tanisaki in the classical case, which says roughly that the matrix of orbital varieties occurring in the associated variety of a simple highest weight module is upper triangular.

ISSN:0092-7872    

DOI:10.1080/00927870008826928

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

摘要:

Double Frobenius algebras (or dF-algebras) were recently introduced by the author. The concept includes finite-dimensional Hopf algebras, adjacency algebras of (non-commutative) association schemes, andC-algebras (character algebras). In this paper we define certain kinds of morphisms of dF-algebras and develop their basic theory. The morphisms generalize homomorphisms of Hopf algebras and ofC-algebras.

ISSN:0092-7872    

DOI:10.1080/00927870008826929

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor

ISSN:0092-7872    

DOI:10.1080/00927870008826930

出版商:Gordon and Breach Science Publishers Ltd.    

年代:2000

数据来源: Taylor