Comments on: Iterated PD

By: Jamie McCarthy

Jamie McCarthy — Thu, 21 Oct 2004 16:57:33 +0000

Think you can beat TFT too? Come submit an entry in my tournament.

By: Patri Friedman

Patri Friedman — Thu, 21 Oct 2004 07:26:53 +0000

This result basically just exploited the fact that it was free to enter multiple teams. That plus the tournament payoff structure. Its not particularly applicable to real life – which is the interesting reason to study these games. I don’t think DD’s examples disprove this assertion. Note that religious martyrs and soldiers both cost resources, significant resources, before they die. The extra Southampton entries cost exactly nothing. Just by creating extra entries, they were able to create extra points for their main teams, at no cost. Real life is all about tradeoffs – even sacrificial lambs and soldiers cost resources. I still think its great that they exploited this design flaw, so we know it exists. But I don’t think it tells us anything about human behavior.

By: reinstein

reinstein — Thu, 21 Oct 2004 03:49:31 +0000

tit-for-tat was beat in spatially distributed SPD games by tit-for-tat with occasional generosity or forgiveness. the result has been know for 15 years. see article by Lezek & Nowick in Nature in 1991 or so.

By: Ethesis

Ethesis — Thu, 21 Oct 2004 02:29:09 +0000

The fact that these games are so sensitive to the rules sets is important, as is the unavailability of threats. But I think we learn from watching them too.

By: dsquared

dsquared — Thu, 21 Oct 2004 00:54:25 +0000

Well, what’s in it for religious martyrs, soldiers who die for the glory of empire, etc, etc? Life has lots of situations with tournament-style payoffs and (unsurprisingly) for this reason offers a fair few examples of Southampton-type strategies.

By: Motoko

Motoko — Thu, 21 Oct 2004 00:22:02 +0000

I dunno, but isn’t the whole point of PD that every program tries to optimize its own result? What’s in it for the slaves?

By: John Quiggin

John Quiggin — Wed, 20 Oct 2004 23:52:30 +0000

The claim that the confederate entrants “won” is dependent on using a tournament-style payoff structure. The average score for the confederates was apparently low, but the masters got the top places thanks to the sacrifices of the slaves. (A nice metaphor for the actual Confederate economy, which produced much the same outcomes).