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Knowledge Engineering for Planning Domain Design. Ron Simpson University of Huddersfield. Automated Planning [A. I. Planning]. Mars Rover Courtesy of NASA/JLP-Caltech. Kitchen Rover. Domain Independent Planning. Declarative Descriptions of Desired State of World [Goal State]

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Knowledge Engineering for Planning Domain Design

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Knowledge EngineeringforPlanning Domain Design

Ron Simpson

University of Huddersfield


Automated Planning [A. I. Planning]

Mars Rover Courtesy of NASA/JLP-Caltech

Kitchen Rover


Domain Independent Planning

  • Declarative Descriptions of

    • Desired State of World [Goal State]

    • Initial State of World

    • Actions available to agents

      • Pre Conditions

      • Post Conditions

  • Planning Problem

    • Synthesise ordered sequence of actions to bring about Goal State


Levels of Ambition

  • Classical

    • Deterministic / Complete / Omniscient

    • World described by lists of simple propositions. No numeric attributes.

    • Actions add or remove propositions from world description. Time not represented

  • Non Classical

    • Add notions of time to actions

    • Allow numeric attributes

    • Non Deterministic / Incomplete Knowledge


Knowledge Engineering

  • Formalisms

    • Develop tractable formalisms capable of being reasoned with.

  • Visualisation

    • Develop tools/image systems to help users create and understand domain of interest.

  • Refractor

    • Develop transformation techniques to allow representations at differing levels of generality to co-exist.


Aims

  • What

    • To develop methods and tools to assist in the :

      • Creation of planning domain specifications.

      • To assist in the task of domain specification validation and testing.

  • How

    • Develop higher level conceptualisations as modelling aids and support these with software tools.

      • Develop the object centric view of planning.

      • Build a prototype environment [GIPO] to demonstrate the utility of the view.

  • Scope

    • Currently classical planning with extensions to HTN Planning and planning with timed processes and numeric properties.


Object Centric View

Tent

  • Plans are strategies to bring about changes in the states of objects within the domain problem.

  • Domain design can be done by charting the possible state changes of the participating object types.

  • Assume all objects of same type have same potential.

Action

Descriptor

State Description


Generic Types

  • Patterns of state transitions reoccur in many domain definitions.

  • Domain definitions may be constructed by composing together common patterns of life histories.

Mobile + Bistate = Portable


Prerequisites

  • Rules for defining the States of object types.

    • Identified by name – parameterised by object Ids

    • Enhanced by properties

      • Identified by property-name -parameterised by property value

  • Rules for defining state transitions.

    • Identified by name and links to source and target states.

  • Rules for merging.

    • Defines rendezvou between object transitions

      • Or object states and Transitions.

    • May augment state by adding association parameters to state predicates [See GIPO Help]


Hiking Domain – Example 1

Transition

Property Value Changing

Satisfies next(x,y)

nextStage(w,v)

Constraint – Number

Satisfies couple(x,y)

Tent

Property : Location

Value present in all

identified states.

Transition

State Changing

Tent

Person

Car

Person

Properties:

Location

Stage

Transition of Tent:

Property Value Changing

Location to Location


Hiking Domain Example 2

Transitions

Require Objects at State

Break Association

Forget Car

Transition

Dependent on Source

Both satisfy next(x,y)

Add Association

Record car

Must Occur Together


Tools Integrated into GIPO

  • Graphical “Life History” Editor to define domains

  • Graphical editors to capture “Instance Information”

  • Auto generate specification from diagrams.

  • Create task specifications.

  • Run integrated planners to solve defined problems.

  • Graphically animate plans produced.

  • Manually create plans in a visual stepper.

  • Translate specifications to PDDL.


Instance and Problem Description

Available States for Sue

State for Sue

Known

Objects


Animation of Plan Solutions

Animation

View

Plan

Inspect Object State


Manual Plan Creation [Stepper]

Emerging Plan

Available Actions

Add Next Action – Choose action parameters


Representing Time and Numeric Properties

  • Hybrid Automata

  • State Change Instantaneous – These are actions

    • may make changes to numeric properties and trigger processes

  • Processes take time.

    • Numeric properties may change as a function of time

  • Events (State Change) may be triggered by processes.

  • These - like processes happen as a result of actions


Filling Bath Domain

Event : when

level > capacity

Process:

Level = flow * #t

Process Trigger

flow(Bath) = flow(Tap)

Process

Precondition


Stepper For Hybrid Automata

Time line

turnOn

turnOff

flood

turnOn

filling

process

plugIn


Conclusion

  • Does the graphical conceptualisation simplify the task? How do we measure this?

  • What is the range of applicability of the technology?

  • Planning seems to be ubiquitous but when is it worthwhile to specify the domain problem?


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