orthonormal comments on Robust Cooperation in the Prisoner's Dilemma - Less Wrong

69 Post author: orthonormal 07 June 2013 08:30AM

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Comment author: orthonormal 10 June 2013 01:35:43AM 4 points [-]

This agent is unexploitable, and mutually cooperates with PrudentBot and FairBot, but it cooperates with CooperateBot (since the fixed point reduces to "P iff Box(P)", which makes the Löbian sentence valid).

Comment author: Will_Sawin 12 June 2013 06:54:49PM 3 points [-]

Notably, this agent is exactly the same as FairBot. Clearly it satisfies P => Provable (Q). We can also check Provable(Q) =>P, since if provable(Q), then P iff Provable(P), so P. Thus P <==> Provable(Q), so it's FairBot.

Comment author: Qiaochu_Yuan 12 June 2013 07:03:34PM *  5 points [-]

Notions of sameness need to be handled with care here in general. There are lots: literally identical code is the most obvious one, then provably identical behavior in PA (against some class of reasonable agents), then provably identical behavior in PA+1 (against some class of reasonable agents)... it's sometimes necessary to use the first notion of sameness because opponents may not behave fairly, e.g. they may punish exactly one program, so in general the set of opponents you want to prove sameness with respect to also matters.

Comment author: Will_Sawin 12 June 2013 10:09:04PM *  3 points [-]

I believe this argument proves identical behavior against all modal agents, and identical behavior of modal agents against.