1. Week 6: PDDL, itSIMPLE and running “state of the art” planners Lee McCluskey, room 3/10 Email lee@hud.ac.uklee@hud.ac.uk http://scom.hud.ac.uk/scomtlm/cha2555/

2. Artform Research Group Planning – up to now Looked at the basics planning: domain models, problems, and engines Planning as heuristic search through state space looking for a state which “satisifes” the goal Implementation of a state space planner in Prolog

3. Artform Research Group This Week’s Overview PDDL – structure and use, GUIs for building domain models Planners – MetricFF and LPG PDDL – see wikipedia for useful references

4. Artform Research Group PDDL (planning domain description language)..is a family of REPRESENTATION LANGUAGES used to encode planning domains It is used by the IPC - “International Planning Competition” held every 2 years co-located with the Int. Planning Conference (ICAPS). The IPC websites have many, many examples of planning domains, using various flavours of the family of PDDL languages.

5. Artform Research Group r1 r3 r5 r7 r4 r2 bracelet locket ring +Sword +Cudgel Key-1 r6 p45 Key-2 troll orc p57 p25 p35 p24 p47 p56 Aragorn Boromir +Knife shield spell golem lock-2 lock-1 p67 p12 RUNNING EXAMPLE - A SIMPLE GAME WORLD

6. Artform Research Group Using PDDL A domain represented with PDDL has two kinds of files: 1.Domain file This is essentially the domain model: it defines the syntax for predicates and actions. 2.Planning problem file(s) These file(s) define planning problem(s) in terms of an initial state, a number the objects and a goal condition

7. Artform Research Group Domain File … has the following elements: Domain name ( define (domain game) Kind of PDDL (planners check this..) ( :requirements :strips :equality :typing … ) Types – for objects (:types player monster treasure key … ) Predicates – variables ? (:predicates (roompos ?x1 - player ?x2 - room) …

8. Artform Research Group Domain File - Operator Schema (:action fight_and_kill_monster :parameters ( ?x1 - player ?x2 - room ?x3 - passage ?x4 - protection ?x5 - weapon ?x6 - monster) :precondition (and (roompos ?x1 ?x2) (contains ?x2 ?x3) (protection_in_use ?x4 ?x1) (weilding ?x5 ?x1) (awake ?x6) (guarded ?x3 ?x6) ) :effect (and (used_up ?x4) (not (protection_in_use ?x4 ?x1)) (destroyed ?x5) (not (weilding ?x5 ?x1)) (killed ?x6 ?x1) (not (awake ?x6)) (open ?x3) (not (guarded ?x3 ?x6)) ) )

9. Artform Research Group PDDL – Problem file (define (problem task1) (:domain game) (:objects aragorn boromir - player golem troll orc - monster ring locket bracelet – treasure key1 key2 - key knife sword cudgel – weapon shield spell - protection r1 r2 r3 r4 r5 r6 r7 - room p12 p23 p24 p25 p45 p47 p57 p67 p35 p56 - passage) (:init (contains r2 p23) (contains r3 p23) (contains r2 p24) …etc etc (:goal (and (killed orc aragorn) (killed troll boromir) … …

10. Artform Research Group Graphical User Interfaces for domain modelling Motivation No need to write PDDL manually Easy to run the planners Can automatically constructs the planning domain model from the diagrams / object-oriented designs Can do consistency checking / validation Tools GIPO – Univ of Huddersfield, uses OCL, won best tool support at ICAPS’05, not supported anymore  ItSIMPLE – Unv of Sao Paulo, uses UML, won best tool support at ICAPS’09

11. Artform Research Group Main versions of PDDL PDDL1.2 – basic version – like game example PDDL2.1 – numerics, durative actions..built in functions like >, decrease, increase..conditions on the start and end of actions Eg google “settlers domain PDDL”.. PDDL+ - processes, events, continuous variables..

12. Artform Research Group Planners that accept some version of PDDL brought to you by itSIMPLE Most planners use the “ignore delete list” heuristic – very powerful FF (v1.2) Uses (mainly) greedy search + “ignore delete list” MetricFF (v2.1) Like FF but with durative actions etc LPG Specifically written for v2.1, uses a form of the “plangraph” (see later in course)