5th International Planning Competition

Deterministic Part

Organizing Committee

Alfonso Gerevini, University of Brescia, Italy (chair)
Yannis Dimopoulos, Unversity of Cyprus, Cyprus
Patrik Haslum, Linkoeping University, Sweden
Alessandro Saetti, University of Brescia, Italy

New: Software tools for generating test problems in most IPC5 domains

The international planning competition is a biennial event organized in the context of the International Conference on Planning and Scheduling, which has several goals, including analyzing and advancing the state-of-the-art in automated planning systems; providing new data sets to be used by the research community as benchmarks for evaluating different approaches to automated planning; emphasizing new research issues in planning; promoting the acceptance and applicability of planning technology.

The fifth international planning competition, IPC-5 for short, has been organized in the context of ICAPS-06. As in the fourth competition, IPC-5 and its organization is split into two parts: the Deterministic Track, that considers fully deterministic and observable planning (previously also called "classical" planning), and the Probabilistic (or non-deterministic) Track organized by Blai Bonet and Bob Givan, that considers non deterministic planning (for more information see the website of the "probabilistic track").

The deterministic part of IPC-5 has two main novelties with respect to previous competitions. Firstly, while considering the CPU-time, we intend to give more emphasis to the importance of plan quality, as defined by the problem plan metric. Partly motivated by this reason, we significantly extended PDDL to include some new constructs, aiming at a better characterization of plan quality by allowing the user to express strong and "soft" constraints about the structure of the desired plans, as well as strong and soft problem goals. The new language, called PDDL3, was developed in strict collaboration with Derek Long.

In PDDL3.0, the version of PDDL3 used in the competition, we can express problems for which only a subset of the goals and plan trajectory constraints can be achieved (because they conflict with each other, or achieving all them is computationally too expensive), and where the ability to distinguish the importance of different goals and constraints is critical. A planner should try to find a solution that satisfies as many soft goals and constraints as possible, taking into account their importance and their computational costs. Soft goals and constraints, or preferences, as they are called in PDDL3.0, are taken into account by the plan metric, which can give a penalty for failure to satisfy each of the problem preferences (or, conversely, a bonus for satisfying them).

Another novelty of the deterministic part of IPC-5 which required considerable efforts concerns the test domains (for more details see the "Domains" page): we designed five new planning domains, together with a large collection of benchmark problems. In order to make PDDL3.0 language more accessible to the competitors, for each test domain, we developed various variants using different fragments of PDDL3.0 with increasing expressiveness. In addition, we re-used two domains from previous competitions, extended with new variants including some of the features of PDDL3.0. The IPC-5 test domains have different motivations. Some of them are inspired by real world applications; others are aimed at exploring the applicability and effectiveness of automated planning for new applications or for problems that have been investigated in other field of computer science; while the domains from previous competitions are used as sample references for measuring the advancement of the current planning systems with respect to the existing benchmarks.

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