Adaptive AI Engine for RTS Games

Discussing the theory and practice

Case Representation Technique

Posted by Ogail on December 1, 2009

  • Abstract:
    • Any case-based planning system deals with 5 problems: Case representation, retrieval, reuses, revise and retain. In this article we discuss the case representation (the plan contents and the case base design) of the CBP system.
  • We define a case C as a tuple of four objects:
    • C = <Goal(s), WorldState, Plan, Performance>
    • Where:
      • Goal(s): goal(s) that this case satisfies.
      • WorldState: is the state of the world in the current situation.
      • Plan: sequence of actions that will achieve the goal(s).
      • Performance: is a real value in the range [0,1] that reflects the utility of choosing that case for that state, where higher values indicate higher performance.
  • We’ve found that it’s wasting of memory and time if we make all of the cases contain the same WorldState because certain cases just require a little knowledge of the world to work. As an example suppose that we need to represent a case for solving problem of collecting a resource with a certain amount, what would the number of assaults I have will help in this problem? Rather we just need a little knowledge that will help. Below the case representation of the resource collecting goal:
    • Goal:
      • CollectResource (Gold, MaxInfluence).
    • WorldState:
      • Number of gold mines.
      • Distance between gold mines and nearest gold mine collector.
      • Number of free or useless peons.
    • Plan:
      • Train(3, peon).
      • Assign(3, peons, GoldMiner).
      • Build(1, Farm).
    • Performance:
  • Number of gold collected in 1 minute.

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