Sequence diagrams are a popular technique for describing interactions between software entities. However, because the OMG group's UML standard is not based on a rigorous mathematical structure, it is impossible to deduce a single interpretation for the notation's semantics, nor to understand precisely how its different fragments interact. While there are a lot of suggested semantics in the literature, they are too mathematically demanding for the majority of software engineers, and often incomplete, especially in dealing with the semantics of lifeline creation and deletion. In this work we describe a simple semantics based on the theory of regular languages, a mathematical theory that is a standard part of the curriculum in every computer science undergraduate degree and covers all the major compositional fragments, and the creation and deletion of lifelines.

翻译：序列图是一种描述软件实体间交互的流行技术。然而，由于OMG组织的UML标准并非基于严格的数学结构，无法推导出该符号语义的唯一解释，也无法精确理解其不同片段如何交互。尽管文献中存在大量建议的语义，但它们对大多数软件工程师而言数学要求过高，且通常不完整，特别是在处理生命线创建与删除的语义方面。本文提出一种基于正则语言理论的简单语义，该数学理论是计算机科学本科课程的标准组成部分，涵盖所有主要组合片段以及生命线的创建与删除操作。