Message Sequence Charts & Sequence Diagrams are graphical models that represent the behavior of distributed and concurrent systems via the scheduling of discrete and local emission and reception events. We propose an Interaction Language (IL) to formalize such models, defined as a term algebra which includes strict and weak sequencing, alternative and parallel composition and four kinds of loops. This IL is equipped with a denotational-style semantics associating a set of traces (sequences of observed events) to each interaction. We then define a structural operational semantics in the style of process algebras and formally prove the equivalence of both semantics.

中文翻译：

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环回交互的结构化操作语义

消息序列图和序列图是图形模型，它们通过调度离散和本地发射和接收事件来表示分布式系统和并发系统的行为。我们提出了一种交互语言（IL）来对这种模型进行形式化，定义为术语代数，其中包括严格和弱排序，替代和并行组成以及四种循环。该IL配备了一种名词化样式的语义，该语义将一组迹线（观察到的事件的序列）与每个交互相关联。然后，我们以过程代数的方式定义结构化操作语义，并正式证明这两种语义的等效性。