一句话:给出可逆素事件结构的操作刻画,并证明其对应于一类可逆因果网。
可逆素事件结构是对素事件结构的扩展,用于抽象描述能够撤销计算步骤的过程;事件结构长期被用于连接操作模型(Petri网、进程演算)与指称模型。此前仅对满足因果尊重的子类给出了操作对应。本文为完整的可逆素事件结构给出操作刻画,证明它们对应于上下文Petri网的一个子类——可逆因果网。可逆因果网的独特之处在于,因果关系由抑制弧而非变迁后集与前集的重叠恢复,从而能够从操作层面解释违反因果顺序的可逆性。
Reversible prime event structures extend the well-known model of prime event structures to represent reversible computational processes. Essentially, they give abstract descriptions of processes capable of undoing computation steps. Since their introduction, event structures have played a pivotal role in connecting operational models (traditionally, Petri nets and process calculi) with denotational ones (algebraic domains). For this reason, there has been a lot of interest in linking different classes of operational models with different kinds of event structures. Hence, it is natural to ask which is the operational counterpart of reversible prime event structures. Such question has been previously addressed for a subclass of reversible prime event structures in which the interplay between causality and reversibility is restricted to the so-called cause-respecting reversible structures. In this paper, we present an operational characterisation of the full-fledged model and show that reversible prime event structures correspond to a subclass of contextual Petri nets, called reversible causal nets. The distinctive feature of reversible causal nets is that causality is recovered from inhibitor arcs instead of the usual overlap between post and presets of transitions. In this way, we are able to operationally explain also out-of-causal order reversibility.