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.

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。

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