VHPOP: Versatile Heuristic Partial Order Planner

TL;DR

VHPOP is a versatile partial order planner that integrates recent heuristic and flaw selection strategies, supporting durative actions and outperforming previous POCL planners in domain independence and problem-solving capability.

Contribution

It introduces novel flaw selection strategies, adapts heuristics for plan reuse, and supports durative actions, enhancing the effectiveness and versatility of POCL planning.

Findings

Outperforms previous POCL planners in problem-solving.

Effective in domains with durative actions.

Combines recent heuristics with flaw selection strategies.

Abstract

VHPOP is a partial order causal link (POCL) planner loosely based on UCPOP. It draws from the experience gained in the early to mid 1990's on flaw selection strategies for POCL planning, and combines this with more recent developments in the field of domain independent planning such as distance based heuristics and reachability analysis. We present an adaptation of the additive heuristic for plan space planning, and modify it to account for possible reuse of existing actions in a plan. We also propose a large set of novel flaw selection strategies, and show how these can help us solve more problems than previously possible by POCL planners. VHPOP also supports planning with durative actions by incorporating standard techniques for temporal constraint reasoning. We demonstrate that the same heuristic techniques used to boost the performance of classical POCL planning can be effective in domains with durative actions as well. The result is a versatile heuristic POCL planner competitive with established CSP-based and heuristic state space planners.