Prisoner's Dilemma (Need strategies)

Rules of Prisoner's Dilemma are simple:

You face an opponent. You have two choices: Defect, or Cooperate. If you defect and your opponent defects, neither player gets a point. If you cooperate and your opponent defects, you lose a point and your opponent gains 5. If you both cooperate, you both get 3 points.

This game is often played out in nature. The obvious choice for one person would be to defect, because if your opponent cooperates and you defect, the payoff is bigger for you, while if your opponent defects and you defect, the payoff is still bigger for you. But what happens when you iterate this game 200 times? What I plan to do is create 20 strategies for playing this game, pit them up against each other, and tally up their points from each individual playing out against each individual 200 times. I have a few theories on what strategies might be best. I have 16 thus far, I need 4 more, although a lot of my strategies are fairly simple, so if you guys give me better ones I'll replace the simple ones with those. I'm going to be running this simulation on a computer.

Each "personality" must predetermine what it does based on it's opponents previous moves. It can store as many previous moves as it likes in its memory, but that can be the only input. Alternatively, it does not need to use its opponents moves at all if it does not want to.

Examples of some of my personalities in case you need examples:

Tit for Tat: Cooperates on the first turn, then mimics what it's opponent did on the previous turn.

Grudger: Cooperate each time until it's opponent defects. Then defect each time.

Random: Randomly pick the decision.

Defect first, then do the opposite of what your opponents previous turn was.

I don't see why anyone would ever do anything but defect.

You Opponent Result (You/Opponent) D D +1/+1 You benefit equally D C +5/-1 You benefit more C D -1/+5 You benefit less C C +3/+3 You benefit equally

So if you always defect, without fail, you cannot lose.

Make that persaonality: Winner

I don't see why anyone would ever do anything but defect. You Opponent Result (You/Opponent) D D +1/+1 You benefit equally D C +5/-1 You benefit more C D -1/+5 You benefit less C C +3/+3 You benefit equally So if you always defect, without fail, you cannot lose. Make that persaonality: Winner

Bob beat me to it.

EDIT: Although, by just purely defecting, you also can't win if your opponent constantly defects as well. The best strategy, IMO, would be to cooperate/defect rotate at first, until you have more points, and once you have even one more point than your opponent, start defecting constantly. This way, not only can you never lose, but they can never win, and the game can never end in a draw.

Well, the only way you can actually win is if you defect and your opponent cooperates. Otherwise, you can never get more points than him. The game's broken.

Actually, yeah, even if you cooperate, the outcome would still be either tied or losing, so you should NEVER cooperate, ever. Broken game.

Actually, yeah, even if you cooperate, the outcome would still be either tied or losing, so you should NEVER cooperate, ever. Broken game.

If everyone chose to only defect, then yes, anyone who cooperates would lose. But if the point of the game is to accumulate as many points as possible clearly a two-man cooperative strategy is the best. Win/Lose will not be calculated in a one-on-one type scenario, but rather the total points accumulated throughout playing everyone.

You Opponent Result (You/Opponent) D D +1/+1 You benefit equally D C +5/-1 You benefit more C D -1/+5 You benefit less C C +3/+3 You benefit equally

Just wanted to correct this so nobody got confused:

You Opponent Result (You/Opponent) D D 0/0 You benefit equally D C +5/-1 You benefit more C D -1/+5 You benefit less C C +3/+3 You benefit equally

Oh, your post says "If you defect and your opponent defects, you neither player gets a point." Somehow, I read that as both players get a point. You should change that too for clarity's sake.

Oh, your post says "If you defect and your opponent defects, you neither player gets a point." Somehow, I read that as both players get a point. You should change that too for clarity's sake.

KK, will do.

Well, actually I thought it was clear (aside from the typo).

You're a sup mod, if you wouldn't mind would you change it to how you think it makes it more clear. I'm not really sure how to reword that.

Oh it's clear enough. Just when I first read it, I guess the typo threw me.

Anyhow, so you're saying that like 10 people will all play each other, and then when they're done, the person with the most points wins? Do each of the games last a certain number of turns (1, 10 20), or is it to a point total (10pts, 100pts, whatever)?

Oh it's clear enough. Just when I first read it, I guess the typo threw me. Anyhow, so you're saying that like 10 people will all play each other, and then when they're done, the person with the most points wins? Do each of the games last a certain number of turns (1, 10 20), or is it to a point total (10pts, 100pts, whatever)?

Yea. I plan on having 20 personalities play against each other, with each game lasting 200 turns.