项的代入定理

摘要

The relationship of i-equivalence and j-equivalence of valuation predigests the proof of substitution theorem of term. And the proof shows structure of first-order language and the relation among valuations in first-order language.%引入两个引理分析了一阶语言中赋值的性质，简化了项的代入定理的证明，新的证明过程更能反映一阶语言的结构和等价的赋值之间的关系．