中文摘要：

对Pi-演算进行语法扩展，提出了一种新的演算：SetPi-演算，在Pi-演算原有语义的基础上引入了“集合”的思想，从而解决了Pi-演算无法添加进程的弊端。详细给SetPi-演算的形式化表示方法及其语义，刻画了SetPi-演算的结构同余规则和归约规则等，并进一步对SetPi-演算的描述能力进行了界定和分析；最后将SetPi-演算应用于本体演化领域，描述本体演化的基本变更操作，实现了其形式化建模。

英文摘要：

This paper presented a new calculus： SetPi-Calculus with the idea of＂Set＂ based on the original semantics of Pi-calculus, to solve the problem of adding a process in Pi-Calculus. We gave the details of formalization and semantic explanation, described the properties of structure congruence, reduced rules of SetPi-caleulus and analyzed its expressive power. Finally, SetPi-calculus was applied to the field of ontology evolution, to describe its basic change operations and achieved a formal model.