Declarative process modelling languages focus on describing a process by restrictions over the behaviour, which must be satisfied throughout the whole process execution. Hence, they are well suited for modelling knowledge-intensive processes with many decision points. However, such models can be hard to read and understand, which affect the modelling and maintenance of the process models tremendously as well as their execution. When executing such declarative (multi-perspective) process models, it may happen that the execution of activities or the change of data values may result in the non-executability of crucial activities. Hence, it would be beneficial to know all consequences of decisions to give recommendations to the process participants. A look-ahead attempts to predict the effects of executing an activity towards possible consequences within an a priori defined time window. The prediction is based on the current state of the process execution, the intended next event and the underlying process model. While execution engines for single-perspective imperative process models already implement such functionality, execution approaches, for multi-perspective declarative process models that involve constraints on data and resources, are less mature. In this paper, we introduce a simulation-based look-ahead approach for multi-perspective declarative process models. This approach transforms the problem of a context-aware process simulation into a SAT problem, by translating a declarative multi-perspective process model and the current state of a process execution into a specification of the logic language Alloy. Via a SAT solver, process trajectories are generated that either satisfy or violate this specification. The simulated process trajectories are used to derive consequences and effects of certain decisions at any time of process execution. We evaluate our approach by means of three examples and give some advice for further optimizations.

声明性流程建模语言着重于通过限制行为来描述流程，而行为必须在整个流程执行中得到满足。因此，它们非常适合对具有许多决策点的知识密集型过程进行建模。但是，此类模型可能难以阅读和理解，这极大地影响了流程模型的建模和维护以及其执行。当执行这样的声明性（多角度）流程模型时，可能会发生活动的执行或数据值的更改可能导致关键活动无法执行。因此，了解决策的所有结果以向流程参与者提供建议将是有益的。前瞻性尝试预测在事先定义的时间窗口内针对可能的后果执行活动的效果。该预测基于流程执行的当前状态，预期的下一个事件和基础流程模型。尽管用于单角度命令式过程模型的执行引擎已经实现了这种功能，但是用于涉及数据和资源约束的多角度声明式过程模型的执行方法还不成熟。在本文中，我们为多角度声明式过程模型引入了一种基于模拟的预见方法。这种方法将上下文感知过程仿真的问题转换为SAT问题，通过将声明式多角度流程模型和流程执行的当前状态转换为逻辑语言Alloy的规范。通过SAT求解器，可以生成满足或违反此规范的过程轨迹。模拟的过程轨迹用于在过程执行的任何时间导出某些决策的结果和效果。我们通过三个示例评估我们的方法，并为进一步优化提供一些建议。