Question

In the minmax algorithm,How to determine when your function reaches the end of the tree and break the recursive calls.

I have made a max function in which I am calling the min function. In the min function , what shud I do?? For max function, I am just returning the bestscore.

def maxAgent(gameState, depth):
      if (gameState.isWin()):
        return gameState.getScore()
      actions = gameState.getLegalActions(0);
      bestScore = -99999
      bestAction = Directions.STOP

      for action in actions:
        if (action != Directions.STOP):
          score = minAgent(gameState.generateSuccessor(0, action), depth, 1)
          if (score > bestScore):
            bestScore = score
            bestAction = action
      return bestScore

def minvalue(gameState,depth,agentIndex):
       if (gameState.isLose()):
         return gameState.getScore()
       else:
         finalstage = False
         number = gameState.getNumAgents()
         if (agentIndex == number-1):
           finalstage = True
           bestScore = 9999
           for action in gameState.getLegalActions(agentIndex):
             if(action != Directions.STOP

I could not understand how to proceed now?I not allowed to set the limit of depth of tree. it has to be arbitrary.

Answer 1

Usually you want to search until a certain recursion depth (e.g. n moves in advance, when playing chess). Therefore, you should pass the current recursion depth as a parameter. You may abort earlier when your results do not improve, if you can determine that with little effort.