ftp.nice.ch/pub/next/games/card/Zenda.README

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Zenda: a Prisoners' Dilemma Game 
for the NeXT Computer

a.  This application was written by Hal Varian, with some assistance from 
    Joseph Klein.   
    The address for Hal Varian is given at the end of the file.

b.  Economics

c.  Zenda is an implementation of a Prisoners' Dilemma game for a network
    of NeXT computers.  

d.  Zenda has been used for research to illustrate a way that "contracts" 
    can be used to induce cooperation in class Prisoners' Dilemma games.
    It may also be useful in the classroom.

e.  Zenda was developed under NeXTstep 2.1, but it should also run on 3.0.

f.  The file Referee.rtf  tells how to install Zenda.
    The file Player.rtf should be given to the players as instructions. 

The first stage of Zenda is a classic Prisoners' Dilemma.
Human subjects do pretty much as the theory predicts---after 6 or 7
rounds most people play the "defect" strategy.

The twist on the classic Prisoners' Dilemma comes in the second stage of
Zenda, where I offer the "pay for play" option.  The subgame perfect
equilibrium of this two-stage game is the efficient outcome.    
This has been confirmed in my experiments in the laboratory.   

The second stage of Zenda is a variation on the "compensation mechanism". 
This is a general mechanism to solve many kinds of externalities problems.
It is described in my paper, "A Solution to the Problem of Externalities when
Agents are Well-Informed."

I found that if I run more than 8 subjects at a time, the network performance
deteriorates significantly.   I intend to rewrite the code when I move to
distributed objects in NeXTstep 3.0 to see if this improves performance.

The file DataAnalysis.ma uses some Mathematica routines to analyze the data
generated by Zenda.

If you use this code for something interesting, let me know about it.
---
Hal.Varian@umich.edu        Hal Varian
voice: 313-764-2364             Dept of Economics
fax:     313-764-2364             Univ of Michigan
                                                    Ann Arbor, MI 48109-1220

These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.