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Making Graphplan Incremental And Cooperative Graphplan

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Input list of added and deleted facts at time i. ... Add new facts and new satisfied operators to graph. ... happens since adding facts means checking each ... – PowerPoint PPT presentation

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Title: Making Graphplan Incremental And Cooperative Graphplan


1
Making Graphplan IncrementalAnd Cooperative
Graphplan
  • Aaron Drew
  • Ian Port

2
Robo-soccer Domain
  • Used a 5x10 sized board
  • Traditional squares
  • Robots could move in any of the eight directions
  • N, E, W, S, NE, NW, etc.
  • Goal of the ball was not set
  • Set in the facts

3
Robo-soccer Domain (cont.)
  • Actions
  • Graphplan only had control of one team.
  • Pass
  • To any friendly robot
  • Get-ball
  • Adjacent squares or current square
  • Drop-ball
  • For getting it into the goal
  • Steal-ball
  • From other robots

4
Facts for domain
  • These are facts for graphplan on our domain
  • There were 4 robots, and one ball and goal.
  • Time Facts Exclusive Pairs
  • 2 151 1172
  • 3 205 3728
  • 4 245 6634
  • 5 263 8108

5
Normal Graphplan
  • Goal is B on Table. Initial is On B A, On Table
    A, Hand Empty, and Clear B.

6
Normal Graphplan (2)
  • Add a single fact to the initial state.

7
Incremental Graphplan
  • Same behavior as normal graphplan for first plan.

8
Incremental Graphplan
  • Add On Table F as before.
  • Far fewer operators considered.

9
Incremental Algorithm
  • Input list of added and deleted facts at time i.
  • Find used operators which are now unsatisfied and
    unused operators which are satisfied.
  • Add new facts and new satisfied operators to
    graph. Remove delete facts and unsatisfied
    operators from graph.
  • Update mutices.
  • Find next set of added and deleted facts.
  • Repeat until at the previous solution level and
    perform graphplan's normal search.

10
Failed Challenges
  • Find a way to add and delete operators without
    considering every one.
  • Instantiate new facts when the time has already
    passed (graphplan's code doesn't support this).
  • Figure out what caused mallocs to crash.

11
Incremental Accomplishments
  • Deletion of facts working.
  • File format to specify the added and deleted
    facts at one time.
  • Algorithm for adding facts mostly in code, but
    some important parts undoable in graphplan.

12
Pseudo Results
  • On an obviously unsolvable problem, incremental
    graphplan took a little longer to find the
    impossibility.
  • When a plan was still reachable in the same
    length plan, incremental graphplan was much
    faster.

13
Meaning of Results
  • Our results apply to domains with only deletions.
  • When adding new facts as well, the time taken
    increases to the same as graphplan.
  • This happens since adding facts means checking
    each operation at each level, which is exactly
    what graphplan normally does.
  • Only savings in real domains is not checking
    operators already in the graph.

14
Cooperation?
  • We had planned to make two graphplans work
    together towards a goal after incremental
    planning worked.
  • Each plan could add and delete conditions to help
    the other reach its goals.
  • Example would be two robosoccer Aibos, one
    passing to square 1,1 and telling the other that
    the change was happening, then the other updating
    its plan to score based on the new information.
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