Planning systems and its

1
Planning systems and its applications in
software engineering

• Saša Tošic, M. Ivanovic
• Risan, 2007

2
Contents

• What are planning systems
• Agent planning package
• Planning systems and SE
• Example

3
What are planning systems?

• Action-based systems that generates plans
• Plan is a sequence of parameterized actions which
  transforms initial states into a goal state
• Planning formalisms and languages Strips, ADL,
  PDDL
• PDDL (planning domain definition language)
  standard planning language

4
Example

• Planning sequence
• Plan A(x, y), B(x, y), C(x, y)

A(x, y)
C(x, y)
B(x,y)
Goal State
Initial State
Temporary states
5
What do we need?

• Planning instance
• Planning Domain
• Actions
• Predicates
• Functions
• Types
• Constants

• Planning problem
• Initial state of a system
• Goal (set of tasks to be achieved)

6
Actions in planning systems

• Actions in planning systems
• Name
• Parameters
• Preconditions
• Effects
• Duration (default 1)
• Cost, probability,

7
APP Agent planning package

• Developed at University in Novi Sad
• Helps to create intelligent agents
• Domain independent planning system for PDDL2.1
• Written in Java in form of a Java package
• Enables plan creation and execution

8
APP Agent planning package

• APP can handle several planning instances
• Generated plans are part of a planning instance

9
APP Agent planning package

• Modules
• Data manipulation
• Plan searching
• Plan execution and monitoring
• Plan validation and verification

10
APP Agent planning package

• Types of a plan
• SingleAction
• Serial plan
• Parallel plan
• Alternative plan
• Multiple plans
• Plans can be mixed

11
Modeling and model checking

• We can create a model of our software and check
  it
• Modeling
• Initial state must be modeled (using objects,
  constants, predicates, functions)
• One action in planning domain is one or more
  actions in our software

12
Model checking

• Planning systems can check if actions are modeled
  well
• Model checking
• How we can do something in our software?
• What is the plan for that goal?
• How we can detect errors?
• No plan (it is not possible to do it)
• Invalid plan

13
Example

• Planning sequence
• Plan A(x, y), B(x, y), C(x, y)

A(x, y)
C(x, y)
B(x,y)
Goal State
Initial State
Temporary states
14
Example

• (action A
• parameters (?x ?y objects)
• precondition (and (point ?x))
• effects (connected ?x ?y))
• (action B
• parameters (?x ?y objects)
• precondition (selected ?x ?y)
• effects (connected ?x ?y))

15
Example

• (action C
• parameters (?x ?y objects)
• precondition (connected ?x ?y)
• effects (doneC))
• Initial state (point x) (point y)
• Goal (doneC)

16
Example

• Plan generated by APP no plan is found
• Reason
• (action A
• parameters (?x ?y objects)
• precondition (and (point ?x) (point ?y))
• effects (connected ?x ?y))

17
Example

• Plan generated by APP A(x, y), C(x, y)
• Reason
• (action A
• parameters (?x ?y objects)
• precondition (and (point ?x) (point ?y))
• effects (selected ?x ?y))

18
Example

• Plan generated by APP
• A(x, y), B(x, y), C(x, y)
• APP can automatically create plans for large
  number of goals

19
Conclusion

• Powerful tool for model checking
• Detects different kinds of errors
• Simulation of plan execution can help to detect
  errors

20
The End

• Thank you for your attention