Dynamic Epistemic Logic (DEL) provides a framework for epistemic planning that is capable of representing non-deterministic actions, partial observability, higher-order knowledge and both factual and epistemic change. The high expressivity of DEL challenges existing epistemic planners, which typically can handle only restricted fragments of the whole framework. The goal of this work is to push the envelop of practical DEL planning, ultimately aiming for epistemic planners to be able to deal with the full range of features offered by DEL. Towards this goal, we question the traditional semantics of DEL, defined in terms on Kripke models. In particular, we propose an equivalent semantics defined using, as main building block, so-called possibilities: non well-founded objects representing both factual properties of the world, and what agents consider to be possible. We call the resulting framework DELPHIC. We argue that DELPHIC indeed provides a more compact representation of epistemic states. To substantiate this claim, we implement both approaches in ASP and we set up an experimental evaluation to compare DELPHIC with the traditional, Kripke-based approach. The evaluation confirms that DELPHIC outperforms the traditional approach in space and time.

翻译：动态认知逻辑（DEL）提供了一个用于认知规划的框架，能够表示非确定性动作、部分可观测性、高阶知识以及事实与认知变化。DEL的高表达性对现有认知规划器构成挑战——这些规划器通常只能处理整个框架中的受限片段。本工作的目标是拓展实际DEL规划的边界，最终使认知规划器能够处理DEL提供的全部特征。为此，我们对DEL的传统语义（基于克里普克模型定义）提出质疑。具体而言，我们提出一种等价语义，其核心构建模块为所谓的"可能性"：一种非良基对象，同时表征世界的事实属性以及智能体认为可能的状态。我们将这一框架称为DELPHIC。我们论证DELPHIC确实能够提供更紧凑的认知状态表征。为证实这一主张，我们在ASP中实现了两种方法，并设计实验评估以比较DELPHIC与传统的基于克里普克的方法。评估结果证实DELPHIC在空间和时间上均优于传统方法。