Planning with Object Creation

Augusto B. Corrêa, Giuseppe De Giacomo, Malte Helmert, Sasha Rubin

Keywords: classical planning, automated planning, heuristic search

TL;DR: We introduce an extension to classical planning where action effects can create and delete objects of the task.

Abstract: Classical planning problems are defined using some specification language, such as PDDL. The domain expert defines action schemas, objects, the initial state, and the goal. One key aspect of PDDL is that the set of objects cannot be modified during plan execution. While this is fine in many domains, sometimes it makes the modeling much more complicated. This not only impacts the performance of the planners, but it also requires the domain expert to bound the number of required objects beforehand, which might be an intractable problem by itself. Here, we introduce an extension to the classical planning formalism, where action effects can create and remove objects. This problem is semi-decidable, but it becomes decidable if we can bound the number of objects at any given state, even though the state-space is still infinite. On the practical side, we extend the Powerlifted planning system to support this PDDL extension. Our results show that Powerlifted does not lose efficiency by supporting this extension while allowing for easier PDDL models.

Category: Long

Student: Graduate

Submission Number: 80