Categoricity in multiuniversal classes

The third author has shown that Shelah's eventual categoricity conjecture holds in universal classes: class of structures closed under isomorphisms, substructures, and unions of chains. We extend this result to the framework of multiuniversal classes. Roughly speaking, these are classes with a closure operator that is essentially algebraic closure (instead of, in the universal case, being essentially definable closure). Along the way, we prove in particular that Galois (orbital) types in multiuniversal classes are determined by their finite restrictions, generalizing a result of the second author.     

格序群的极小扭类,准素扭类和极扭类

本文给出了格序群的扭类是准素扭类的一个充分必要条件，证明了任一非零扭类至少包含一个极小扭类，从而将文〔１〕和〔２〕中在有限制条件情况下的有关结论推广到无任何限制条件的情形。本文还给出了一个扭类是极扭类的几个充分必要条件，并得到了格序群的极扭类、准素扭类和极小扭类之间的关系。     

Characterization of Hereditary Rings ViaInjectivity and Projectivity Classes

Throughout,allringsconsideredhaveanidentity,modulesareunitalleftmodulesandE(M)standsfortheinjectivehullofM.Now,letSbeaclassofmodules,thatisacollectionofR-modulessuchthatifM∈SthenanyR-moduleisomorphictoMbelongstoS.Wewillfreelyusethenotation,terminologyandresultsof[2].Recently,thereareanumberofwellknowntheoremswhichcharacterizeringsintermsofinjectiveandprojectivemodules(cf.[1],[3]and[4]).In[5,6]injectivityclassesandprojec-tivityclassesareintroducedandsimilarresultsremaintruewheninjectivity(…     

格序群的C-根类和K-根类

本文研究了Ｃ-根类（即凸ｌ－子群格可分辨根类）和Ｋ－根类．证明了：投射ｌ－群、强投射ｌ－群、两两分裂ｌ－群、Ｆ－群等许多ｌ－群类都是ｌ－子群格可分辨的,但Ｈａｍｉｌｔｏｎｌ－群不是;Ｃ－根类格是根类格的一个有伪补的闭子格,而且是根类半群的一个子半群．每个凸Ｏ一子群都是闭的,而且给出了由一簇Ｋ一根类及一个根类所生成的Ｋ－根类的形式．     

论有限群元素共轭类的平均长度

本文研究有限群元素共轭类的平均长度问题.利用初等群论方法和有限群特征标理论,在共轭类平均长度为某一定数时,获得了对有限群结构的刻划,且对有限群数量性质的研究是有意义的.     

When are definable classes tilting and cotilting classes?

It is known that tilting classes are of finite type, while cotilting classes are not always of cofinite type. We investigate this phenomenon. By using a bijection between definable classes of left modules and definable classes of right modules, we prove that it reflects the asymmetry existing between the notions of covers and envelopes or, otherwise stated, right and left approximations.In particular we show that there exist definable torsion classes containing the injective modules which are not tilting classes.     

上协边类纤维丛表示的若干性质

本文研究了底空间为实射影空间时上协边类纤维丛表示的若干性质．     

各向异性Sobolev及Besov类的平均单边宽度

给出了各向异性Sobolev类及各向异性Besov类的平均单边宽度,获得了相应的弱渐近估计.     

Grid classes and partial well order

We prove necessary and sufficient conditions on a family of (generalised) gridding matrices to determine when the corresponding permutation classes are partially well-ordered. One direction requires an application of Higman?s Theorem and relies on there being only finitely many simple permutations in the only non-monotone cell of each component of the matrix. The other direction is proved by a more general result that allows the construction of infinite antichains in any grid class of a matrix whose graph has a component containing two or more non-monotone-griddable cells. The construction uses a generalisation of pin sequences to grid classes, together with a number of symmetry operations on the rows and columns of a gridding.     

On Similar Special Classes

Two special classes are said to be similar if they determine the same upper radical. A necessary and sufficient condition for a special radical to be generated by distinct similar special classes is given and all similar special classes generating a given special radical are described.     

Generalized Vector Equilibrium Problems with Trifunctions

In this paper, we study the existence of strong and weak solutions of the generalized vector equilibrium problems for trifunctions. Two special classes of vector-valued trifunctions are introdcued, called the classes of (SPM) and (GPM), respectively. Some existence results for strong solutions associated to functions of these classes are given.     

Canonical Finite Diagrams and Quantifier Elimination

We revisit the theory of amalgamation classes but we do not insist on staying within elementary classes.     

Lower bound for quantum integration error on anisotropic Sobolev classes

We study the approximation of the integration of multivariate functions in the quantum model of computation. Using a new reduction approach we obtain a lower bound of the n-th minimal query error on anisotropic Sobolev class R（Wpr（[0, 1]d）） （r R＋d）. Then combining this result with our previous one we determine the optimal bound of n-th minimal query error for anisotropic Hblder- Nikolskii class R（H∞r（[0,1]d）） and Sobolev class R（W∞r（[0,1]d））. The results show that for these two types of classes the quantum algorithms give significant speed up over classical deterministic and randomized algorithms.     

Ultra‐differentiable classes and intersection theorems

The aim of the paper is to study the relation between ultra‐differentiable classes of functions defined in terms of estimates on derivatives on one hand and in terms of growth properties of Fourier transforms of suitably localized functions in the class on the other hand. We establish this relation for the ultra‐differentiable classes introduced in 6 , 16 , and show that the classes of 6 , 16 , can be regarded as inhomogeneous Gevrey classes in the sense of 22 . We also discuss a number of properties of the weight functions used to define the respective classes and of their Young conjugates.     

Bordism Classes of Involutions on RP（2n）、CP（2n） and HP（2n）

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＩｎｔｈｉｓｐａｐｅｒ,ＲＰ（ｎ）,ＣＰ（ｎ）,ＨＰ（ｎ）ｒｅｐｒｅｓｅｎｔｓｎ－ｄｉｍｅｎｓｉｏｎａｌｒｅａｌｐｒｏｊｅｃｔｉｖｅｓｐａｃｅ,ｃｏｍｐｌｅｘｐｒｏｊｅｃｔｉｖｅｓｐａｃｅ,ｑｕａｔｅｒｎｉｏｎｉｓｐｒｏｊｅｃｔｉｖｅｓｐａｃｅｒｅｓｐｅｃｔｉｖｅｌｙ．Ｍ～２ＲＰ（ｎ）ｍｅａｎｓｔｈｅｍｏｄ２ｃｏｈｏｍｏｌｏｇｙｒｉｎｇｏｆＭｉｓｉｓｏｍｏｒｐｈｉｃｔｏｔｈａｔｏｆＲＰ（ｎ）：Ｈ（Ｍ;Ｚ２）≈Ｈ（ＲＰ（ｎ）;Ｚ２）．Ｗｅｉｎｔｒｏｄｕｃｅｔｈｅ…     

Steinitz classes of tamely ramified Galois extensions of algebraic number fields

The Steinitz class of a number field extension K/k is an ideal class in the ring of integers Ok of k, which, together with the degree [K:k] of the extension determines the Ok-module structure of OK. We call Rt(k,G) the set of classes which are Steinitz classes of a tamely ramified G-extension of k. We will say that those classes are realizable for the group G; it is conjectured that the set of realizable classes is always a group. We define A^′-groups inductively, starting with abelian groups and then considering semidirect products of A^′-groups with abelian groups of relatively prime order and direct products of two A^′-groups. Our main result is that the conjecture about realizable Steinitz classes for tame extensions is true for A^′-groups of odd order; this covers many cases not previously known. Further we use the same techniques to determine Rt(k,Dn) for any odd integer n. In contrast with many other papers on the subject, we systematically use class field theory (instead of Kummer theory and cyclotomic descent).     

A note on parallel and alternating time

A long standing open question in complexity theory over the reals is the relationship between parallel time and quantifier alternation. It is known that alternating digital quantifiers is weaker than parallel time, which in turn is weaker than alternating unrestricted (real) quantifiers. In this note we consider some complexity classes defined through alternation of mixed digital and unrestricted quantifiers in different patterns. We show that the class of sets decided in parallel polynomial time is sandwiched between two such classes for different patterns.     

A Bijection for Eulerian-equivalence Classes of Totally Cyclic Orientations

Gioan showed that the number of cycle reversing classes of totally cyclic orientations of a given graph can be calculated as an evaluation of the corresponding Tutte polynomial. We note that the concept of cycle reversing classes of orientations coincides with that of Eulerian-equivalence classes considered by Chen and Stanley, and Kochol. Based on this coincidence, we give a bijective proof of Gioan’s result. Precisely, the main result of the paper is an algorithmic bijection between the set of Eulerian-equivalence classes of totally cyclic orientations and the set of spanning trees without internally active edges.      

On the gap between two classes of analytic functions

Two large classes of analytic functions are defined, so that one contains the other. Sharp coefficient bounds for quadratic polynomials falling in the gap between these two classes are given.