有穷关系模型上的模态可定义  

Modal Definable on Finite Relational Models

作　　者：裘江杰[1] 

机构地区：[1]中国人民大学哲学院,北京100872

出　　处：《湖南科技大学学报（社会科学版）》2013年第3期31-33,共3页Journal of Hunan University of Science and Technology(Social Science Edition)

基　　金：中国人民大学科学研究基金(中央高校基本科研业务费专项资金资助)项目(12XNJ024)

摘　　要：一阶语言与模态语言从不同侧面描述关系模型。Van Benthem刻画定理从抽象的角度指出,在描述关系模型层面上模态语言表达力弱于一阶语言。从可定义这一相对具体的角度表明,即使在讨论有穷的关系模型时,模态语言也严格弱于一阶语言。Van Benthem characterization theorem tells us that the expressive power of modal language is weaker than that of the first order language in describing relational models.The difference between the expressive power of modal language and that of the first order language does not disappear even in the situation of considering finite relational models based on the concept of modal definable,via finding a necessary condition of modal definable.Moreover,this condition is also sufficient condition in this finite situation.

关 键 词：关系模型 模态可定义 齐集 

分 类 号：C55[社会学]