Relative Projectivity of the Modules $$L_p$$

Mathematical Notes - In the paper, criteria are given for the relative projectivity of the $$L_p$$ -spaces regarded as left Banach modules over the algebra of bounded measurable functions ( $$1le...     

Relative Projectivity of Modules and Cohomology Theory of Finite Groups

In the modular representation theory of finite groups the theory of projectivity relative to subgroups is of fundamental importance. To generalize this notion the theory of projectivity relative to modules was introduced by the first author. Our aim is to show some aspects of cohomology theory of finite groups concerning projectivity of modules relative to both subgroups and modules. We shall give some applications to the cohomology theory; especially we shall calculate the mod 2 cohomology algebras of finite groups with wreathed Sylow 2-subgroups.     

Finite Lattices as Lattices of Relative Congruences of Finite Unars and Abelian Groups

It is proved that every finite lattice is isomorphic to an R-congruence lattice of a finite unar (finite Abelian group), as well as to a lattice of R-varieties for some locally finite finitely axiomatizable quasivariety of unars (Abelian groups) R.     

Free Distributive Completions of Partial Complete Lattices

The free distributive completion of a partial complete lattice is the complete lattice that it is freely generated by the partial complete lattice in the most distributive way. This can be described as being a universal solution in the sense of universal algebra. Free distributive completions generalize the constructions of tensor products and of free completely distributive complete lattices over partially ordered sets.     

Projectivity and freeness over comodule algebras

Let be a Hopf algebra and an -simple right -comodule algebra. It is shown that under certain hypotheses every -Hopf module is either projective or free as an -module and is either a quasi-Frobenius or a semisimple ring. As an application it is proved that every weakly finite (in particular, every finite dimensional) Hopf algebra is free both as a left and a right module over its finite dimensional right coideal subalgebras, and the latter are Frobenius algebras. Similar results are obtained for -simple -module algebras.

     

Some Ideal Lattices in Partial Abelian Monoids and Effect Algebras

Congruences and ideals in partial Abelian monoids (PAM) are studied. It is shown that the so-called R ₁-ideals in cancellative PAMs (CPAM) form a complete Brouwerian sublattice of the lattice of all ideals, and they are standard elements of it. In a special class of CPAMs, effect algebras, properties of ideals and congruences are studied in relation to the generalized Sasaki projections and dimensional equivalence.     

混合偏熵与关联熵

定义联系模糊性和随机性的混合集、混合偏熵与关联熵以及混合关联系数，研究了其性质，并举例说明混合关联系数在现实生活中的应用。     

Projectivity, transitivity and AF-telescopes

Continuing our study of projective -algebras, we establish a projective transitivity theorem generalizing the classical Glimm-Kadison result. This leads to a short proof of Glimm's theorem that every -algebra not of type I contains a -subalgebra which has the Fermion algebra as a quotient. Moreover, we are able to identify this subalgebra as a generalized mapping telescope over the Fermion algebra. We next prove what we call the multiplier realization theorem. This is a technical result, relating projective subalgebras of a multiplier algebra to subalgebras of , whenever is a -subalgebra of the corona algebra . We developed this to obtain a closure theorem for projective -algebras, but it has other consequences, one of which is that if is an extension of an MF (matricial field) algebra (in the sense of Blackadar and Kirchberg) by a projective -algebra, then is MF. The last part of the paper contains a proof of the projectivity of the mapping telescope over any AF (inductive limit of finite-dimensional) -algebra. Translated to generators, this says that in some cases it is possible to lift an infinite sequence of elements, satisfying infinitely many relations, from a quotient of any -algebra.

     

Projectivity of modules for infinitesimal unipotent group schemes

In this paper, it is shown that the projectivity of a rational module for an infinitesimal unipotent group scheme over an algebraically closed field of positive characteristic can be detected on a family of closed subgroups.     

Injectivity, Projectivity and Supercuspidal Representations

Let G be a reductive p-adic group. Consider the category ofsmooth (complex) representations of G in which a (fixed) closedcocompact subgroup of the centre acts by a (fixed) character.It is well known that the supercuspidal representations in thiscategory are both injective and projective. It is shown that,conversely, an admissible injective or projective object isnecessarily supercuspidal.     

分配格与模格的另一二条件等价定义

针对分配格与模格的格等式定义问题,得知了二条件是定义分配格与模格的最少条件,并进一步证明了Sholander's basis是定义分配格的最短最少变量格等式,最后又从分配格和模格的基本定义出发给出了新的分配格的二条件和三条件等价定义等式及模格的二条件与三条件等价定义等式.     

Projectivity and independent sets in powers of graphs

We investigate the relationship between projectivity and the structure of maximal independent sets in powers of circular graphs, Kneser graphs and truncated simplices. © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 162–171, 2002     

Projectivity of acts and morita equivalence of monoids

In this paper we shall consider a non-additive category of A-modules, that is, instead of a ring A we take a monoid A which acts on sets from the left. These objects will be called A-acts. We investigate indecomposable A-acts and generators and characterize projectives in this category. For a given monoid A we describe all monoids B such that the category of B-acts is equivalent to the category of A-acts. In particular we find that equivalence of these categories yields an isomorphism between the monoids A and B if A is a group or finite or commutative. This differs from the additive case where the categories of modules over a commutative field and its ring of nxn matrices are equivalent. Finally we give examples of non-isomorphic monoids A and B such that the corresponding categories are equivalent.     

Fuzzy集的偏熵与关联熵

在文献[1]的基础上,推广模糊熵的概念。首次定义Fuzzy集的偏熵、关联熵和关联熵系数等新概念。对其主要性质进行讨论,并与模糊散度建立联系．得到一些重要结果。     

拟半连续格和交半连续格

作为半连续格的推广, 引入了拟半连续格的概念. 讨论了拟半连续格的基本性质. 在拟半连续格上得到了类似于拟连续偏序集的一些主要结果. 同时探讨了半连续格、拟半连续格、交半连续格、交连续格、强连续格几种不同结构之间的关系. 最后,讨论了半连续函数空间仍是半连续格的条件.     

交换环上的单模的射影性与内射性

在本短文中主要研究了交换环上的单模的射影性与内射性之间的关系。主要证明了:交换环上射影单模必是一个内射模;若该环是一个Noether环,则反之亦成立。     

Smooth格和强Smooth格

引入了强smooth格的概念,讨论了smooth格与强smooth格的一些基本性质,证明了强smooth格可用保任意交和Scott闭集之并的映射嵌入到某方体[0,1]X之中.