Representation and Synthesis of C++ Programs for Generalized Planning

TL;DR

This paper proposes a C++ program-based representation for Generalized Planning problems, enabling formal proofs of plan properties, complexity characterization, and efficient solution validation on large instances, outperforming previous heuristic methods.

Contribution

It introduces a novel C++ representation for GP problems that allows formal termination proofs, complexity analysis, and efficient validation, advancing the state of generalized planning methods.

Findings

BFGP++ outperforms previous heuristic search approaches.

C++ programs enable deterministic, grounding-free solution validation.

The approach scales to large instances with thousands of objects.

Abstract

The paper introduces a novel representation for Generalized Planning (GP) problems, and their solutions, as C++ programs. Our C++ representation allows to formally proving the termination of generalized plans, and to specifying their asymptotic complexity w.r.t. the number of world objects. Characterizing the complexity of C++ generalized plans enables the application of a combinatorial search that enumerates the space of possible GP solutions in order of complexity. Experimental results show that our implementation of this approach, which we call BFGP++, outperforms the previous GP as heuristic search approach for the computation of generalized plans represented as compiler-styled programs. Last but not least, the execution of a C++ program on a classical planning instance is a deterministic grounding-free and search-free process, so our C++ representation allows us to automatically validate the computed solutions on large test instances of thousands of objects, where off-the-shelf classical planners get stuck either in the pre-processing or in the search.