# Domain-Independent Cost-Optimal Planning in ASP

## TL;DR

This paper introduces two novel ASP-based approaches for cost-optimal planning, including a makespan-free stepless planning method, demonstrating promising results compared to existing SAT-based planners.

## Contribution

It presents a new stepless planning approach in ASP that guarantees global optimality without relying on makespan, advancing the state of cost-optimal planning methods.

## Key findings

- Stepless planning shows competitive performance in experiments.
- Parallel ASP programs can be engineered for cost-optimal planning.
- Stepless planning has potential advantages over makespan-dependent methods.

## Abstract

We investigate the problem of cost-optimal planning in ASP. Current ASP planners can be trivially extended to a cost-optimal one by adding weak constraints, but only for a given makespan (number of steps). It is desirable to have a planner that guarantees global optimality. In this paper, we present two approaches to addressing this problem. First, we show how to engineer a cost-optimal planner composed of two ASP programs running in parallel. Using lessons learned from this, we then develop an entirely new approach to cost-optimal planning, stepless planning, which is completely free of makespan. Experiments to compare the two approaches with the only known cost-optimal planner in SAT reveal good potentials for stepless planning in ASP. The paper is under consideration for acceptance in TPLP.