Zero-Shot Iterative Formalization and Planning in Partially Observable Environments

In planning, using LLMs not to predict plans but to formalize an environment into the Planning Domain Definition Language (PDDL) has been shown to greatly improve performance and control. While most work focused on fully observable environments, we tackle the more realistic and challenging partially observable environments where existing methods are incapacitated by the lack of complete information. We propose PDDLego+, a framework to iteratively formalize, plan, grow, and refine PDDL representations in a zero-shot manner, without needing access to any existing trajectories. On two textual simulated environments, we show that PDDLego+ not only achieves superior performance, but also shows robustness against problem complexity. We also show that the domain knowledge captured after a successful trial is interpretable and benefits future tasks.