We present alternative approaches to routing and scheduling in Answer Set Programming (ASP), and explore them in the context of Multi-agent Path Finding. The idea is to capture the flow of time in terms of partial orders rather than time steps attached to actions and fluents. This also abolishes the need for fixed upper bounds on the length of plans. The trade-off for this avoidance is that (parts of) temporal trajectories must be acyclic, since multiple occurrences of the same action or fluent cannot be distinguished anymore. While this approach provides an interesting alternative for modeling routing, it is without alternative for scheduling since fine-grained timings cannot be represented in ASP in a feasible way. This is different for partial orders that can be efficiently handled by external means such as acyclicity and difference constraints. We formally elaborate upon this idea and present several resulting ASP encodings. Finally, we demonstrate their effectiveness via an empirical analysis.

翻译：我们提出了回答集编程（ASP）中路径规划与调度的替代方法，并将其应用于多智能体路径发现场景中。核心思想是通过偏序关系而非关联动作与流的时间步长来捕捉时间流，从而消除对规划长度固定上界的需求。这种规避策略的代价是（部分）时间轨迹必须保持无环性，因为相同动作或流的多次出现将无法区分。该方法为路径规划建模提供了有趣的替代方案，且在调度领域具有不可替代性——因为细粒度时间在ASP中无法以可行方式表示。这不同于可通过无环约束和差异约束等外部手段高效处理的偏序关系。我们对该思想进行了形式化阐述，提出了若干相应的ASP编码方案，并通过实证分析验证了其有效性。