中文摘要：

QVT（Query／View／Transformation）Relations无法描述包含嵌套模式，因此在描述流程模型的转换规则时存在一些困难．针对此问题，对QVTRelations进行了扩展，引入了模式因子、嵌套关系表达式和关联端约束这3个概念，并讨论了扩充之后匹配模型和创建模型的语义变化．并用一个例子展示，扩展之后的QVTRelations可以解决流程模型转换的问题．

英文摘要：

QVT （Query/View/Transformation） Relations cannot describe the pattern that includes other patterns, so it has some difficulties in defining the rules of a process model transformation. To solve this problem, the paper extends QVT Relations with three new concepts： Pattern Factor, Nested Relation Expression, and Relationship End Constraint. The paper also discusses the pattern matching and the model creating semantics after the extension. At Last, a case study is presented to show how the extension could deal with process model transformations.