What would be even more fascinating is a round of this contest where the rules allow for self-modification.
As I'm thinking about what to submit, I find myself thinking "it would be useful to know what programs are going to be entered into the context". For instance, if you knew that a number of CliqueBot entires were going to be present, you'd have a strong motivation to make yours a copy.
On reflection, it feels strange to think that way - it feels like I am wishing for information that my program is going to have anyway. "If I know how I want my program to behave if there are copies of program X in the contest, then I can just program it to recognize the program passed to it as X and behave accordingly."
But there's the rub - your program can decide how to play, but it cannot (once submitted) decide what to be.
As the other post mentions, "there's one particularly irksome issue with CliqueBot, and that's the fragility of its cooperation" - you can't be sure for instance how many entries adopt this template exactly, versus one that dispenses with the unnecessary call to get the current time (as I proposed).
(That's what I meant by my earlier remark about "social engineering" - if I can convince people that it's better to adopt my variant of the CliqueBot, then that's the variant that will win more points from mutual cooperation.)
What if your program could self-modify, though? What if the contest rules let your program see the source code of all programs you are competing with, ahead of time, not just the one you're going up against in each individual battle? Then you could for instance notice that one particular copy of CliqueBot is particularly numerous, and self-modify to adopt that template.
Of course, to be fair, the contest should then inform all other programs that you have so self-modified. Programs whose strategy involves simulating other programs might also want to simulate the other programs' reactions to it self-modifying in a particular way, before actually self-modifying.
After the iterated prisoner's dilemma tournament organized by prase two years ago, there was discussion of running tournaments for several variants, including one in which two players submit programs, each of which are given the source code of the other player's program, and outputs either “cooperate” or “defect”. However, as far as I know, no such tournament has been run until now.
Here's how it's going to work: Each player will submit a file containing a single Scheme lambda-function. The function should take one input. Your program will play exactly one round against each other program submitted (not including itself). In each round, two programs will be run, each given the source code of the other as input, and will be expected to return either of the symbols “C” or “D” (for "cooperate" and "defect", respectively). The programs will receive points based on the following payoff matrix:
“Other” includes any result other than returning “C” or “D”, including failing to terminate, throwing an exception, and even returning the string “Cooperate”. Notice that “Other” results in a worst-of-both-worlds scenario where you get the same payoff as you would have if you cooperated, but the other player gets the same payoff as if you had defected. This is an attempt to ensure that no one ever has incentive for their program to fail to run properly, or to trick another program into doing so.
Your score is the sum of the number of points you earn in each round. The player with the highest score wins the tournament. Edit: There is a 0.5 bitcoin prize being offered for the winner. Thanks, VincentYu!
Details:
All submissions must be emailed to wardenPD@gmail.com by July 5, at noon PDT (Edit: that's 19:00 UTC). Your email should also say how you would like to be identified when I announce the tournament results.
Each program will be allowed to run for 10 seconds. If it has not returned either “C” or “D” by then, it will be stopped, and treated as returning “Other”. For consistency, I will have Scheme collect garbage right before each run.
One submission per person or team. No person may contribute to more than one entry. Edit: This also means no copying from each others' source code. Describing the behavior of your program to others is okay.
I will be running the submissions in Racket. You may be interested in how Racket handles time (especially the (current-milliseconds) function), threads (in particular, “thread”, “kill-thread”, “sleep”, and “thread-dead?”), and possibly randomness.
Don't try to open the file you wrote your program in (or any other file, for that matter). I'll add code to the file before running it, so if you want your program to use a copy of your source code, you will need to use a quine. Edit: No I/O of any sort.
Unless you tell me otherwise, I assume I have permission to publish your code after the contest.
You are encouraged to discuss strategies for achieving mutual cooperation in the comments thread.
I'm hoping to get as many entries as possible. If you know someone who might be interested in this, please tell them.
It's possible that I've said something stupid that I'll have to change or clarify, so you might want to come back to this page again occasionally to look for changes to the rules. Any edits will be bolded, and I'll try not to change anything too drastically, or make any edits late in the contest.
Here is an example of a correct entry, which cooperates with you if and only if you would cooperate with a program that always cooperates (actually, if and only if you would cooperate with one particular program that always cooperates):