Generalized APP-Rings

We say a ring R is (centrally) generalized left annihilator of principal ideal is pure (APP) if the left annihilator ? _R (Ra) ⁿ is (centrally) right s-unital for every element a ∈ R and some positive integer n. The class of generalized left APP-rings includes generalized left (principally) quasi-Baer rings and left APP-rings (and hence left p.q.-Baer rings, right p.q.-Baer rings, and right PP-rings). The class of centrally generalized left APP-rings is closed under finite direct products, full matrix rings, and Morita invariance. The behavior of the (centrally) generalized left APP condition is investigated with respect to various constructions and extensions, and it is used to generalize many results on generalized PP-rings with IFP and semiprime left APP-rings. Moreover, we extend a theorem of Kist for commutative PP rings to centrally generalized left APP rings for which every prime ideal contains a unique minimal prime ideal without using topological arguments. Furthermore, we give a complete characterization of a considerably large family of centrally generalized left APP rings which have a sheaf representation.     

Admissibility of unbiased tests for a composite hypothesis with a restricted alternative

This paper discusses -admissiblility and d-admissiblity which are important concepts in studying the performance of statistical tests for composite hypotheses. A sufficient condition for -admissibility is presented. When =1/m, the Nomakuchi-Sakata test, which is uniformly more powerful than the likelihood ratio test for hypotheses min (₁, ₁) = 0 versus min (₁, ₁) > 0, is generalized for a class of distributions in an exponential family, and its unbiasedness and -admissibility are shown. Finally, the case of 1/m is discussed in brief.     

Principal Quasi-Baerness of Rings of Skew Generalized Power Series

Let R be a ring and （S, 〈） be a strictly totally ordered monoid satisfying that 0 〈 s for all s C S. It is shown that if A is a weakly rigid homomorphism, then the skew generalized power series ring [[RS,-〈, λ]] is right p.q.-Baer if and only if R is right p.q.-Baer and any S-indexed subset of S,（R） has a generalized join in S,（R）. Several known results follow as consequences of our results.     

From Pappus’ Theorem to the Twisted Cubic

We discuss a classical result in planar projective geometry known as Steiners theorem involving 12 interlocking applications of Pappus theorem. We prove this result using three dimensional projective geometry then uncover the dynamics of this construction and relate them to the geometry of the twisted cubic.Mathematics Subject Classification (2000). Primary 51N15.     

Testing optimality for quadratic 0–1 unconstrained problems

This paper analyses a necessary and sufficient optimality condition for quadratic pseudo-Boolean unconstrained problems. It is proved that in general testing any necessary and sufficient optimality condition is a difficult task for anyNP-hard problem. An-optimality condition is derived together with an approximation scheme to test it.This work has been supported by the Progetto Finalizzato Trasporti 2, 93.01799.PF74.Professor Paolo Carraresi died unexpectedly on March 5, 1994. At the time of his death this paper had been completed. While undertaking the final revision, the other two authors were reminded just how much they were indebted to Professor Carraresi after many years of common work together.     

Nassrallah-Rahman积分的一个新证明

应用关于ｑ－微分算子的Ｌｅｉｂｎｉｚ公式证明了关于ｑ－微分算子的两个恒等式．利用这些恒等式及ｑ－级数的一些求和公式给出了Ｎａｓｒａｌａｈ－Ｒａｈｍａｎ积分的一个新证明，进而给出了关于ｑ－级数８Φ７的积分表示的一个简易推导     

Perturbation Theory and the Analytic Approach in the Context of the Inclusive τ-Lepton Decay

We perform a comparative analysis of different forms of pertubative expansions in spacelike and timelike regions. In the context of the inclusive -lepton decay, we compare the results obtained using the standard perturbation theory and the Shirkov–Solovtsov analytic approach, which modifies the perturbative expansions such that the new approximations reflect basic principles of the theory, such as renormalization invariance, spectrality, and causality. We show the advantages and self-consistency of the analytic approach in describing the -lepton decay.     

ARIMA(p,d,q)与GM(1,1)模型在洪涝灾害预测中之比较研究——以广东省做实证分析

运用经济时间序列ARIMA(p,d,q)模型与GM(1,1)模型对广东省的洪涝灾害进行了预测.研究结论显示,所建立的ARIMA(p,d,q)模型能够较好的对洪涝灾害进行预测,模型可以运用到各种主要气象灾害风险预测与管理中,但所建立的GM(1,1)模型虽然具有很好的精度,但预测效果并不好.这充分体现了模型选择在预测过程中的重要性.     

The topological jacobson radical of rings. I

In this paper, a topological Jacobson radical of rings is introduced. Several properties of this radical are considered. We investigate the topological Jacobson radical for some constructions of topological rings such as adjunction of the unitary element, completion, direct product with respect to the Tychonoff topology, rings of continuous functions, and polynomial rings.     

Armendariz modules over skew PBW extensions

The aim of this article is to develop the theory of skew Armendariz and quasi-Armendariz modules over skew PBW extensions. We generalize the results of several works in the literature concerning these topics for the context of Ore extensions to another non-commutative rings which can not be expressed as iterated Ore extensions. As a consequence of our treatment, we extend and unify different results about the Armendariz, Baer, p.p., and p.q.-Baer properties for Ore extensions and skew PBW extensions.     

On finite intersections of “henselian valued” fields

In this note we study finite intersections of henselian valued fields, i.e. fields carrying either a henselian valuation ring or a henselian absolute value which is (real-) archimedean. To be more precise, we intersect a finite number of henselian valued respectively real closed fields such that the induced valuation rings respectively orderings generate different V-topologies on the intersection, and investigate its algebraic and valuation-theoretic properties.     

有幺单Γ－环类所确定的上根

结合环根论中由具有单位元的单环类所确定的上根就是Ｂｒｏｗｎ－ＭｃＣｏｙ根．本文指出在Γ－环中，鉴于Γ－环单位元的复杂性质使得有幺单Γ－环类确定的上根演变成８个，进而研究了这些根之间及这些根与Γ－环其它根之间的大小关系．     

Uniquely Covered Radical Classes of ℓ-Groups

It is proved that a radical class of lattice-ordered groups has exactly one cover if and only if it is an intersection of some -complement radical class and the big atom over .     

Serial Rings with T-Nilpotent Prime Radical

In this paper we consider serial rings with T-nilpotent prime radical, factor-rings of which by the prime radical are right Noetherian rings. We prove that the prime quiver of such a ring is a disconnected union of cycles and chains. In the case when the prime quiver of such a serial ring is a chain the prime radical is nilpotent. For serial rings with nilpotent prime radical we introduce an analogue of Kupisch series. Presented by Yu. Drozd Mathematics Subject Classifications (2000) 16P40, 16G10.     

Endoprimitive rings

A class of endoprimitive rings is defined which contains all strongly prime rings and all weakly primitive rings. These rings are characterized in several ways and various facts about strongly prime and weakly primitive rings are generalized. An analog of the Jacobson radical is defined which is shown to be a normal radical lying between the Jacobson and Levitzki radicals.     

关于绝对半素环和绝对半素根

本文了绝对半素环的概念，研究了绝对半素与与半素环及素环之间的关系，讨论了由全体绝对半素环类决定的上根－－绝对半半素根及其性质。     

Σ-Definability in Hereditarily Finite Superstructures and Pairs of Models

We consider the problem of being -definable for an uncountable model of a c-simple theory in hereditarily finite superstructures over models of another c-simple theory. A necessary condition is specified in terms of decidable models and the concept of relative indiscernibility introduced in the paper. A criterion is stated for the uncountable model of a c-simple theory to be -definable in superstructures over dense linear orders, and over infinite models of the empty signature. We prove the existence of a c-simple theory (of an infinite signature) every uncountable model of which is not -definable in superstructures over dense linear orders. Also, a criterion is given for a pair of models to be recursively saturated.     

Superlocals in Symmetric and Alternating Groups

On Aschbacher's definition, a subgroup N of a finite group is called a -superlocal for a prime if . We describe the -superlocals in symmetric and alternating groups, thereby resolving part way Problem 11.3 in the Kourovka Notebook [3].     

Sierpiński Gasket as a Martin Boundary I: Martin Kernels; Dedicated to Professor Masatoshi Fukushima on the occasion of his 60th birthday

We show that a Sierpiski gasket in N dimension is homeomorphic to the minimal Martin boundary of some canonical Markov chain. This provides a new class of examples for the boundary theory of Markov chains and the basis for a harmonic analysis on p.c.f. fractal structures.     

Model companion and model completion of theories of rings

Extending the language of rings to include predicates for Jacobson radical relations, we show that the theory of regular rings defined by Carson, Lipshitz and Saracino is the model completion of the theory of semisimple rings. Removing the requirement on the Jacobson radical (reduced to {0}), we prove that the theory of rings with no nilpotents does not admit a model companion relative to this augmented language.