Li Deyu

The influence of c-normality of subgroups on the structure of finite groups

Abstract A subgroup H of a finite group G is said to be c-normal in G if there is a normal subgroup N of G such that HN=G and H∩N≤HG=coreG(H). In this paper we investigate further the influence of c-normality of some subgroups on the structure of finite groups and generalize some known results.

The influence of c-normality of subgroups on the structure of finite groups II *

A subgroup Hof a finite group Gis said to be c-normal in Gif there exists a normal subgroup Nof Gsuch that HN=Gand H∩ N≤ H G =core G(H).In this paper we shall investigate the influence of c-normality of some subgroups on the strcture of finite groups further, and obtain some results on some kinds of weaker conditions.

Invariant characters of information systems under some homomorphisms

Abstract An information system is one of the very important mathematical models in the field of artificial intelligence. The notion of an information system homomorphism as a kind of tool to study the relation between two information systems was introduced in J.W. Grzymala-Busse (Algebraic properties of knowledge representation systems, in: Proceedings of the ACM SIGART International Symposium on Methodologies for Intelligent Systems, Knoxville, 1986, pp. 432–440). In this paper, some invariant characters of an information system under a homomorphism are discussed.

Invariant characteristics of information systems under some homomorphisms. I

An information system is one of the very important mathematical models in the field of artificial intelligence. The notion of information systems homomorphism as a kind of tools to study the relation between two information systems was introduced by Grzymala-Busse (1986). In this paper, some invariant characteristics of an information system under a homomorphism are discussed.