The Generic Special Scroll of Genus g in P N : Special Scrolls in P3

We study the generic linearly normal special scroll of genus g in P ^N . Moreover, we give a complete classification of the linearly normal scrolls in P ³ of genus 2 and 3.     

A Note on Normality of Cones Over Symmetric Varieties

Let G be a semisimple and simply connected algebraic group, and let H ⁰ be the subgroup of points fixed by an involution of G. Let V be an irreducible representation of G with a nonzero vector v fixed by H ⁰. In this article, we prove a property of the normalization of the coordinate ring of the closure of G·[v] in ?(V).     

On the Projective Normality of Smooth Surfaces of Degree Nine

The projective normality of smooth, linearly normal surfaces of degree 9 in ^N is studied. All nonprojectively normal surfaces which are not scrolls over a curve are classified. Results on the projective normality of surface scrolls are also given.     

Projective supercharacter theory

Abstract

The idea of supercharacters for ordinary characters of a finite group G was introduced by Diaconis and Isaacs and further extended to Brauer characters by Chen and Lewis. The twin concepts of supercharacters and superclasses are further extended here to α-characters of G for α a complex-valued 2-cocycle of G. An α-quasi-supercharacter theory of G arises when the set of α-quasi-supercharacters of G are compatible with the set of α-regular quasi-superclasses of G. The structure of solvable groups that have exactly two α-quasi-supercharacter theories is determined.

Communicated by Mark L. Lewis     

拟连续格的逆极限

给出以保任意交和定向并为态射的拟连续格范畴的逆极限,讨论函子保广义拟连续格逆极限的条件。     

初等算子的正规性

设初等算子E（X）＝n↑∑↑i=1AiXBi，定义E^*(X)=n↑∑↑i=1Ai^*XBi^*我们证明了EE^*＝E^*E当县仅当｛Ai｝和｛Bi｝都是交换的正规算子族，从而回答了由D.Keckic提出的关于初等算子正规性的开问题。我们还给出了E＝E^*的充分必要条件。     

Some Ideals with Large Projective Dimension

For an ideal in a polynomial ring over a field, a monomial support of is the set of monomials that appear as terms in a set of minimal generators of . Craig Huneke asked whether the size of a monomial support is a bound for the projective dimension of the ideal. We construct an example to show that, if the number of variables and the degrees of the generators are unspecified, the projective dimension of grows at least exponentially with the size of a monomial support. The ideal we construct is generated by monomials and binomials.

     

Morita Context的右正规性

本文讨论了Muller提出的第3个公正问题,证明了当PR是忠帝的拟投射生成元,PT＝P,且T作为右R－模有限生成时,PR导出的Morita Context一定是右正规性的,这里T为P在R中的变理想。     

Projective Well-orderings of the Reals

If there is no inner model with ω many strong cardinals, then there is a set forcing extension of the universe with a projective well-ordering of the reals.     

亚纯函数的正规族

In this paper, we deal with the problem of normal families concerning share-values. The results extend and improve some theorems put forward by Miranda, Pang, Chen, Hua and Fang. Moreover, we answer one question posed by Gu, Pang, Fang and so on.     

Projective Character Degree Patterns of p-Groups for p Odd

In this article, we classify up to isomorphism the character tables of 2-generator p-groups of class two.     

Projective Representations of Quivers #

In the first part of this article, we describe the projective representations in the category of representations by modules of a quiver which does not contain any cycles and the quiver A _∞ as a subquiver, that is, the so-called rooted quivers. As a consequence of this, we show when the category of representations by modules of a quiver admits projective covers. In the second part, we develop a technique involving matrix computations for the quiver A _∞, which will allow us to characterize the projective representations of A _∞. This will improve some previous results and make more accurate the statement made in Benson (1991 Benson , D. J. ( 1991 ). Representations and Cohomology I . Cambridge Studies in Advanced Mathematics , Vol. 30 . Cambridge : Cambridge University Press . [Google Scholar]). We think this technique can be applied in many other general situations to provide information about the decomposition of a projective module.     

Canonical geometrically ruled surfaces

We prove the existence of canonical scrolls; that is, scrolls playing the role of canonical curves. First of all, they provide the geometrical version of Riemann Roch Theorem: any special scroll is the projection of a canonical scroll and they allow to understand the classification of special scrolls in P^N. Canonical scrolls correspond to the projective model of canonical geometrically ruled surfaces over a smooth curve. We also prove that the generic canonical scroll is projectively normal except in the hyperelliptic case and for very particular cases in the nonhyperelliptic situation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Projective Character Degree Patterns of Groups of Order p 4

In Ok (2001 Ok , K. S. ( 2001 ). On p-groups of order p ⁴ . Commun. Korean Math. Soc. 16 : 205 – 210 . [Google Scholar]), the structure of the Schur multiplier was found for six of the ten non-Abelian groups of order p ⁴, for p an odd prime number. In this article, using elementary methods, we will establish the structure of the Schur multiplier for the remaining four groups. This subject has only received cursory attention previously and a number of small errors have been made in the existing literature. However, the main result of this article will be to find the projective character degree patterns with multiplicities and the epicentres of all p-groups of order p ⁴.     

一个半参数回归模型的渐近正态性

考虑半多数回归模型yi＝xiβ＋g（xi）＋εi，lin，这里xi是具有已知方差σ的独立同分布随机样本，εi是具有零均值和有限方基σ2的独立同分布随机误差．β，g和εi的分布密度是未知的．本文作者构造了一个具有更小渐近方差的β的一个渐近正态估计．     

Normality concerning the sequence of functions

Let {f_n} be a sequence of functions meromorphic in a domain D, let {h_n} be a sequence of holomorphic functions in D, such that that h(z)→h(z), where h.(z)→0 is holomorphic in D, and let k be a positive integer. If for each n∈N~+, f_n(z)≠0 and f_n~(k)(z)-h_n(z) has at most k distinct zeros(ignoring multiplicity) in D, then {f_n} is normal in D.     

On the Singularities of Surfaces Ruled by Conics

We classify the singularities of a surface ruled by conics: they are rational double points of type A _n or D _n . This is proved by showing that they arise from a precise series of blow-ups of a suitable surface geometrically ruled by conics. We determine also the family of such surfaces which are birational models of a given surface ruled by conics and obtained in a “minimal way” from it.     

多元t分布的一致渐进正态性

讨论了多元t分布一致渐进正态性的条件,利用不等式法估计了二者之间的Kullback-Leibler距离,给出了Kullback-Leibler距离表达式,最后对多元t分布一致渐进正态性进行了模拟验证.     

Fine Control over the Projective Characters of the Centre of a Group

In this article we will study the restriction of the irreducible projective characters of a finite group to a central subgroup. We will also consider under what conditions on the restriction of such irreducible projective characters to an abelian normal subgroup that we can deduce that the subgroup is central. Finally, we will investigate the relationship between the inertia subgroup and the absolute centralizer of a central subgroup relative to a fixed 2-cocycle of the group.