文中从产品知识表达存在的问题出发，提出了基于本体的产品知识表达四层模型，即结构层—行为层—基本功能层—元功能层，给出了各层本体的表示模式。
Because some problems are in the product knowledge representation, so gives the four layers to solve it, which contains the structure layer, behavior layer, basic-function layer and meta-function lay.
最后，粗糙集关系图表示法的知识表达系统研究。
Last, the Research of Rough Set Relationship Graphics Representation Knowledge Base.
基于本体的知识表达是当前知识表示方向的一个研究热点。
Knowledge representation based on ontology is an active research in the study of knowledge representation.
在分析机械产品知识表示形式的基础上，提出基于语义对象的产品知识表达模型方法，阐述了机械产品知识表达模型的信息构成。
According to analyzing methods of knowledge representations for mechanical products design, a new knowledge representation model based on semantic object is described.
此外还提出了与数据无关的多叉树层次结构模型的知识表示方法，它具有很强的表达能力并易于扩展。
The data-independent multi-branch tree hierarchical structure is proposed for the knowledge representation, because it has strong expressing ability and can be easily expanded.
此外还提出了与数据无关的多叉树层次结构模型的知识表示方法，它具有很强的表达能力并易于扩展。
The data-independent multi-branch tree hierarchical structure is proposed for the knowledge representation, because it has strong expressing ability and can be easily expanded.
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