Talk:Prisoner's dilemma

Closed Bag Exchanges and Street Drug Dealing

The following paragraph in the article:

"even if it is in both their best interests to do so." this sentence´s based on pretending that only external and shortisghted "interests" exist. fact is that internal disprofit occurs it´s also a sign for a wider sight of the situation. in short: when both profit (and still have more than enough to live) a third party might disprofit from the situation without knowing it since this third party´s also short sighted and therefore thinks that her disprofit was her own fault.

87.152.123.202 (talk) 20:23, 16 March 2010 (UTC)

Two people meet and exchange closed bags, with the understanding that one of them contains money, and the other contains a purchase. Either player can choose to honor the deal by putting into his or her bag what he or she agreed, or he or she can defect by handing over an empty bag.

reminds me of the open-air drug markets in places like San Francisco's Haight-Ashbury district. To somewhat reduce the obviousness of what they are doing, drug sellers and buyers will use "novel" means of exchanging money and goods, like putting one inside a cup which should have soda inside, with a lid on top and a straw sticking out. The other might place the money ( or the drugs ) between pages in a folded newspaper. In this situation, exactly the same amount of trust is required, and indeed the payoff matrix is identical, as described by Hofstadter.

Obviously I have no reliable statistics, however, defection must be rare enough for this practice to remain widespread. To some extent this is due to tourism ( ie the vanishingly small chance of two "players" meeting again in future ), and there are many other factors which can help explain this behavior. However, the close analogy makes this relevant to the article, and, I believe, the taboo nature of this subject lends interest ... while still modeling human economic interaction with a heavy reliance on trust.

I would love to see something about this in the main article, if others agree with the relevance and think this example helps new readers gain insight? —Preceding unsigned comment added by 206.57.60.147 (talk) 23:34, 30 October 2009 (UTC)

Daniel Ashlock in his book Evolutionary Computation for Modeling and Optimization also uses the example of drug dealing.

69.156.179.128 (talk) 05:05, 18 December 2009 (UTC)

Alexrod's Four Rules

I see nothing about non-envious in his four rules. The passage reads:

`` The analysis of the data from these tournaments reveals four properties which tend to make a strategy successful: avoidance of unnecessary con- flict by cooperating as long as the other player does, provocability in the face of an uncalled-for defection by the other, forgiveness after responding to a provocation, and clarity of behavior so that the other player can recognize and adapt to your pattern of action.

The fourth Alexrod rule is `clarity of behavior' —Preceding unsigned comment added by 69.156.179.128 (talk) 05:09, 18 December 2009 (UTC)

"a 'nice' strategy can never score more than the opponent"

This isn't true. Wouldn't a strategy such as "cooperate until opponent defects, then always defect" be "nice" yet still win?

C,C
C,D
D,C
D,C
D,C

24.34.94.195 (talk) 02:34, 31 December 2009 (UTC)

maximizing his or her own payoff

The phrase in para 3: "In this game, as in all game theory, the only concern of each individual player (prisoner) is maximizing his or her own payoff" is slightly misleading. It might mean maximising his expectation payoff subject to judgemants about what the other player is likely to do. In the classic von Neumannnn and Morgenstern treatment of zero-sum games (The English translation is called "The Theory of Games and Economic Behaviour" published about 1935)each player seeks to mininimise his maximum loss (equivalently maximise his minimum gain).

78.149.201.243 (talk) 12:44, 20 December 2009 (UTC)

For minimax, von Neumann can do it that way since, being zero-sum, it's equivalent to maximizing own (expected) payoff. But, there are exceptions in game theory, so I switched the "as in all" to "as in most". CRETOG8(t/c) 15:36, 20 December 2009 (UTC)

this analysis is too hidebound, in that the rational prisoner will also look to the political consequences of any act of betrayal both in custody and on the street in terms of his obtaining a reputation as a "snitch" or informer, the consequences of which can become very drastic. Thus what is really in the prisoner's interest must be viewed more broadly: keeping silent and doing 6 months is the most prudent choice; in fact keeping silent would be the best choice in all except the more extreme scenarios as a death sentence from other prisoners and gang members on the street is a likely outcome of informing in many situations. —Preceding unsigned comment added by 173.16.203.56 (talk) 01:09, 31 January 2010 (UTC)

It is usually assumed that there is no way for anybody to ever find out if either prisoner defected; they do so in secret. Either way, it doesn't matter: the dilemma is used as an example, not for a literal scenari.Eebster the Great (talk) 16:35, 31 January 2010 (UTC)

XKCD references are not appropriate

See Wikipedia:XKCD. Please stop adding them to the article, and future articles. Snied (talk) 06:35, 1 February 2010 (UTC)

The "Strategy" section seems confusing (to this layman)

It says "In this game, regardless of what the opponent chooses, each player always receives a higher payoff (lesser sentence) by betraying". This just seems wrong to me (only a layman in regards to game theory), because if the opponent chooses to cooperate, then I receive a higher payoff if I also cooperate. I think you meant to say "not knowing what the opponent will choose, each player lessens their chance of receiving the lowest payoff (greatest sentence) by betraying". There is a distinct difference, at least when it comes to prison sentences. 75.52.255.18 (talk) 09:48, 7 February 2010 (UTC)

Suppose you know the other prisoner is going to cooperate. If you cooperate, you will get a six month sentence, but if you betray, you will go free. Therefore you should betray. Suppose, however, you know the other prisoner is going to betray. If you cooperate, you will get a ten year sentence, but if you betray, you will get only a five year sentence. Therefore you still should betray. So regardless of what the other prisoner will do, you should betray. Eebster the Great (talk) 17:48, 7 February 2010 (UTC)

Morality And The Scenario Of PD

If PD is formulated as a scenario of persons suspected of a crime, one might make a game-theoretical explanation of morality regarding PD clearer by eliminating the crime element from the consideration/discussion. That is, shouldn't the morality of PD behaviors be explicitly described as relating to the narrow context of the two prisoners' treatment of one another, rather than left to possible interpretation as relating to the crime itself? Cooperation in crime is usually considered immoral. It's not a needful clarification for folks looking at the matter with the typical eye of someone deeply studying it, but for the casual reader it could help.