排序方式: 共有20条查询结果,搜索用时 15 毫秒
1.
Joost Vercruysse 《数学学报(英文版)》2008,24(10):1655-1674
We show the close connection between apparently different Galois theories for comodules introduced recently in [J. Gomez-Torrecillas and J. Vercruysse, Comatrix corings and Galois Comodules over firm rings, Algebr. Represent. Theory, 10 (2007), 271 306] and [Wisbauer, On Galois comodules, Comm. Algebra 34 (2006), 2683-2711]. Furthermore we study equivalences between categories of comodules over a coring and modules over a firm ring. We show that these equivalences are related to Galois theory for comodules. 相似文献
2.
Jan Paseka 《International Journal of Theoretical Physics》2008,47(1):291-296
Following B. Banaschewski’s work on so-called K-flat projective frames, we treat their non-commutative generalization, i.e. K-flat projective quantales. Besides a categorical definition of a K-flat projective quantale we also give an elementary characterization in terms of a binary relation on the quantale, and we
prove that K-flat projective quantales are precisely the coalgebras for a certain comonad on the category of quantales. Finally we define
and study a natural notion of K-coherentness for quantales.
Financial Support of the Ministry of Education of the Czech Republic under the project MSM0021622409 is gratefully acknowledged. 相似文献
3.
G. Grätzer, H. Lakser, and E. T. Schmidt proved that every finite distributive lattice D with n join-irreducible elements can be represented as the congruence lattice of a lattice L with O(n2) elements. G. Grätzer, I. Rival, and N. Zaguia gave kn, < 2, as a lower bound for the size of such a lattice L; a sharper form, 1/64(n/log2n)2, of this result was given by Y. Zhang.In this note, we apply a recent result of R. Freese, to obtain 1/16 n2/log2n as a lower bound. We also give a direct proof of Freese's result. 相似文献
4.
We study the interaction between the lattices of relations of members of a general Morita context. The pairs of reversing-order
maps are defined, which determine the dualities between the lattices of ‘closed’ relations. Under rather weak conditions,
these dualities can be composed obtaining the projectivities defined by simple maps.
PACS: 02.10.De,02.10.Hh. 相似文献
5.
Michał Farnik 《Mathematische Nachrichten》2016,289(2-3):243-246
We strengthen the classical Kleiman‐Chevalley projectivity criterion by showing that it is enough to assume that instead of . 相似文献
6.
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(… 相似文献
7.
类比于一般环上模的内射类,定义了幺半群上的S-系的内射类和投射类,并利用它们刻画了几类特殊的幺半群.证明了完全内射幺半群和完全拟内射幺半群是等价的.并且证明了对于标致幺半群S,它是完全投射的当且仅当它是完全拟投射的当且仅当它上面的投射S-系构成了一个投射类. 相似文献
8.
一种多指标决策与评价的新方法 总被引:3,自引:0,他引:3
邱根胜 《数学的实践与认识》2004,34(11):47-50
指出了多指标决策与评价投影法所用的决策矩阵无量纲化方法的不妥之处及在应用中存在的问题 ,提出了一种新方法 ,并用实例说明了该方法是可行合理的 . 相似文献
9.
《Quaestiones Mathematicae》2013,36(3):281-287
Abstract We begin with the notion of K-flat projectivity. For each biframe L we then introduce a binary relation ?L on it. The K-flat projective biframes are exactly such biframes with each element a of the total (first, second) part approximated by the elements x of the total (first, second) part, x?L a and the relation ?L being stable wrt. the meet operation on L. Further on, we introduce the notion of a K-comonad and characterize K-flat projective biframes as those biframes having a coalgebra structure for the K-comonad. The K-coherent biframes and K-flat projective biframes are coreflective in all biframes. 相似文献
10.
基于vague集投影及距离的模糊多指标决策 总被引:7,自引:1,他引:6
提出了两个vague值投影和距离的概念,并在此基础上给出了考虑指标权重影响的基于vague集投影和距离的多指标模糊决策方法.在这个方法中,利用候选方案在理想方案上的投影和距离来求出最佳方案.此方法与文献现有的应用vague集相似度度量进行决策的方法相比较,新方法更加合理且弥补了现有方法的不足之处.最后对实例进行分析计算,算例验证了该方法的有效性. 相似文献