We consider approaches for causal semantics of Petri nets, explicitly representing dependencies between transition occurrences. For one-safe nets or condition/event-systems, the notion of process as defined by Carl Adam Petri provides a notion of a run of a system where causal dependencies are reflected in terms of a partial order. A well-known problem is how to generalise this notion for nets where places may carry several tokens. Goltz and Reisig have defined such a generalisation by distinguishing tokens according to their causal history. However, this so-called individual token interpretation is often considered too detailed. A number of approaches have tackled the problem of defining a more abstract notion of process, thereby obtaining a so-called collective token interpretation. Here we give a short overview on these attempts and then identify a subclass of Petri nets, called structural conflict nets, where the interplay between conflict and concurrency due to token multiplicity does not occur. For this subclass, we define abstract processes as equivalence classes of Goltz-Reisig processes. We justify this approach by showing that we obtain exactly one maximal abstract process if and only if the underlying net is conflict-free with respect to a canonical notion of conflict.

翻译：我们考虑的是Petri Net的因果语义学方法,明确代表过渡发生时的依赖性。对于一个安全网或条件/事件系统,卡尔·亚当·彼得里所定义的程序概念提供了一种概念,即运行一个以部分顺序反映因果依赖性的系统。一个众所周知的问题是如何将这个概念概括为蚊帐,因为其位置可能带有若干象征物。Goltz和Reisig将这种概括性定义为根据其因果历史区分象征物。然而,这种所谓的个人象征性解释往往被认为过于详细。一些方法解决了界定一个更抽象的进程概念的问题,从而获得所谓的集体象征性解释。在这里,我们简单概述这些尝试,然后确定一个称为结构冲突网的亚类,因为在那里,冲突与象征多重性货币之间的相互作用不会发生。关于这个小类,我们把抽象过程定义为Goltz-Reisig进程的等同类。我们证明这个方法的理由是,我们获得一个完全的抽象过程,如果根本的网络概念是无冲突,并且只有对冲突的深层次概念没有尊重。