Hi all,

I'm playing around with using ECJ to evolve game-playing agents. In

the particular, at the moment, I'm prototyping my ideas by evolving

Tic-Tac-Toe players. I want fitness to be evaluated by each program

playing 5 matches with randomly selected opponents. Their fitness will

be a sum of the number of wins they wind up with, plus half a point

for each draw. Each match consists of playing the same engine twice,

once with X and once with O. I'm not sure if I'm implementing this

correctly or not, so I thought I'd see what you all think.



Here are my evaluation settings:

eval = ec.coevolve.CompetitiveEvaluator

eval.style = rand-2-ways

eval.group-size = 5



Here is the evaluate function:



    public void evaluate(EvolutionState state, Individual[] ind,

boolean[] updateFitness, boolean countVictoriesOnly, int [] someInts,

int threadnum)

    {

        float [] fitnesses = new float [] {0,0}; // resulting

fitnesses of the individuals



    	reset(); // set up a new game

        int index = 0; // index of individual whose turn it is

        //state.output.message("Game 1:");

        while (moves.size() > 0){ // i.e., while legal moves exist

        	// calling eval on an individual causes it to choose a move

        	((GPIndividual)ind[index]).trees[0].child.eval(state,

threadnum, (GPData)input, stack, (GPIndividual)ind[0], this);

            makemove(); // make the chosen move, calculate next set of

legal moves

            index = (index + 1) % 2; // next player's turn

        }

        if (game_over()){ // bad name, but this checks to see whether

there are 3 marks in a row

        	// someone won

        	int winner = (index + 1) % 2;

        	fitnesses[winner] += 1; // 1 point for a win

        } else {

            fitnesses[0] += 0.5; // half point for a tie

            fitnesses[1] += 0.5;

        }



        // set up a second game

        reset();

        index = 1; // the other individual goes first this time

        //state.output.message("Game 2:");

        while (moves.size() > 0){

        	((GPIndividual)ind[index]).trees[0].child.eval(state,

threadnum, (GPData)input, stack, (GPIndividual)ind[0], this);

            makemove();

            index = (index + 1) % 2;

        }

        if (game_over()){

        	// someone won

        	int winner = (index + 1) % 2;

        	fitnesses[winner] += 1;

        } else {

            fitnesses[0] += 0.5;

            fitnesses[1] += 0.5;

        }



        // games are over: time to actually update the fitnesses

        for (int i = 0; i < 2; i++)

        	if (updateFitness[i]){

        		KozaFitness fitness = ((KozaFitness)ind[0].fitness);

        		fitness.setStandardizedFitness(state,

fitness.standardizedFitness() + fitnesses[i]);

        	}

        }