

Students get class-wide As by boycotting test, solving Prisoner's Dilemma - soneca
http://boingboing.net/2013/02/19/students-get-class-wide-as-by.html?utm_source=dlvr.it&utm_medium=twitter&utm_campaign=Feed%3A+boingboing%2FiBag+%28Boing+Boing%29

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dragonwriter
I pointed this out in the other thread on this
(<http://news.ycombinator.com/item?id=5244777>), but this isn't at all
Prisoner's Dilemma even before any consideration of communication because _the
payoff matrix is wrong_.

For a game to be PD, there must be a strict ordering of payoffs. In descending
order of payoff, they must be (where "I" describes the player whose payoff is
being considered, and "you" is the other player; this is the same for both
players):

    
    
      I defect, you cooperate
      I cooperate, you cooperate
      I defect, you defect
      I cooperate, you defect
    

There are two important features that come from this set of payoffs: (defect,
defect) is the only Nash Equilibrium -- the only point where a unilateral
strategy change by any player makes their payoff worse, and defection is a
dominant strategy for each player (that is, without knowing the other players
chosen strategy, each player knows they can maximize their own payoff by
defection.)

The actual ordering of payoffs for this exercise is:

    
    
      I cooperate, you cooperate (I get 100% on test with no risk)
      I defect, you cooperate; or I defect, you defect (I get whatever score I would get from taking the test, which is never better than 100%, and could be worse) 
      I cooperate, you defect (I get 0% on the test)
    

In this case, both cooperate/cooperate and defect/defect are Nash Equilibria,
and, unlike in the Prisoner's Dilemma, and there is no dominant strategy. This
is a game that has much more room for cooperation than PD, because cooperation
in PD always means giving up a gain that you could have realized, where in
this case cooperation is the ideal self-interested behavior if the other
player is cooperating.

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soneca
Just a point, that some students were there to ensure no one breaks the
boycott, and if someone did, these would come in too. So, enforcing the
other's decisions and changing your own after see their decision is not
exactly Prisoner's Dilemma. Nice mobilization, and nice reactio from the
professor too, though.

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lutusp
Strictly speaking, it's not "prisoner's dilemma" if the students can talk to
each other and agree on a plan. In a real prisoner's dilemma, the participants
have to guess at the motivations and actions of other participants -- this is
part of the game's definition:

<http://en.wikipedia.org/wiki/Prisoners_dilemma>

Quote: "Two members of a criminal gang are arrested and imprisoned. Each
prisoner is in solitary confinement _with no means of speaking to or
exchanging messages with the other_."

