Intermediate Results on the Complexity of STRIPS$_{1}^{1}$

TL;DR

This paper investigates the computational complexity of a restricted version of STRIPS planning, exploring whether the problem remains NP-hard or becomes easier when operators are limited to one precondition and one effect.

Contribution

It introduces new methods including SAT solver experiments, the literal graph, and Petri net mappings to analyze the complexity of STRIPS$^1_1$.

Findings

PSPACE-completeness for ground literals with limited operators

Open question on NP-completeness of STRIPS$^1_1$

New tools for complexity analysis of planning problems

Abstract

This paper is based on Bylander's results on the computational complexity of propositional STRIPS planning. He showed that when only ground literals are permitted, determining plan existence is PSPACE-complete even if operators are limited to two preconditions and two postconditions. While NP-hardness is settled, it is unknown whether propositional STRIPS with operators that only have one precondition and one effect is NP-complete. We shed light on the question whether this small solution hypothesis for STRIPS$^1_1$ is true, calling a SAT solver for small instances, introducing the literal graph, and mapping it to Petri nets.