There exist LW readers who believe that Cooperate is the dominant strategy in PD.

Can you provide links to comments that are examples of this? If so, I'd like to look at them to confirm and then to make sure I have downvoted and/or corrected them as necessary. Without seeing the examples I assign roughly 0.5 probability to them existing, with most of the remaining probability mass going to "There exist comments that defy CDT in a way that some readers may consider to be equivalent to declaring that Cooperate is dominant but is in fact not a claim about strategic dominance at all".

I had that discussion in person, so I can't point to comments. There may have been some confusion about the claims made, such that the claim I understood them to be making is different from the claim that they made, and the specific game in question was 2-iteration PD with the nonstandard payoff matrix (50,50; 100,0; 0;100; 25,25), but I think they were using cached thoughts for the discussion, rather than something that applied to the specific case but not the general.

Prisoner's dilemma tournament results

by AlexMennen 1 min read9th Jul 2013124 comments


The prisoner's dilemma tournament is over. There were a total of 21 entries. The winner is Margaret Sy, with a total of 39 points. 2nd and 3rd place go to rpglover64 and THE BLACK KNIGHT, with scores of 38 and 36 points respectively. There were some fairly intricate strategies in the tournament, but all three of these top scorers submitted programs that completely ignored the source code of the other player and acted randomly, with the winner having a bias towards defecting.

You can download a chart describing the outcomes here, and the source codes for the entries can be downloaded here.

I represented each submission with a single letter while running the tournament. Here is a directory of the entries, along with their scores: (some people gave me a term to refer to the player by, while others gave me a term to refer to the program. I went with whatever they gave me, and if they gave me both, I put the player first and then the program)

A: rpglover64 (38)
B: Watson Ladd (27)
D: skepsci (24)
E: Devin Bayer (30)
F: Billy, Mimic-- (27)
G: itaibn (34)
H: CooperateBot (24)
I: Sean Nolan (28)
J: oaz (26)
K: selbram (34)
L: Alexei (25)
M: LEmma (25)
N: BloodyShrimp (34)
O: caa (32)
P: nshepperd (25)
Q: Margaret Sy (39)
R: So8res, NateBot (33)
S: Quinn (33)
T: HonoreDB (23)
U: SlappedTogetherAtTheLastMinuteBot (20)