No person may contribute to more than one entry.

This is important, because otherwise the contest devolves into who can submit the most copies of AbsolutismBot (cooperate with programs that share it's source code, otherwise defect)

I think that any submitted program can be improved by combining it with AbsolutismBot. If you're playing with someone who submitted the same program for you, cooperate (they can't defect against you in this scenario, since they're running identical source code). If they aren't running the same code, run whatever program lies underneath it.

I think this could get generalized to cooperation with everyone who has the AbsolutismBot "wrapper", since it doesn't matter what the code after the AbsolutismBot section does. In English (since I don't know how to program in Scheme), the program would be like this:

If the first 117 characters of the other program are the same as the first 117 characters of this program, cooperate. Otherwise, do some other strategy.

All players that implement this strategy will cooperate with each other. Granted, this doesn't help them win the tournament since it isn't a relative advantage compared to other AbsolutismBots - it just makes everyone who doesn't do this lose the tournament.