Iterated Prisoner Dilemma

matlab experiment

Jie Bao, since 2003-04-12

 Experimental report (Will be online soon)

----------- strategy.m

% strategy: strategy for agent in iterated prisoner dilemma 
% Jie Bao 2003-04-12
% Input:
%    method
% Return value:
%    1 : Cooperation , 2 : Defect


function decision = strategy(method)
    switch lower(method)
        case 'nice', 
            %disp('Nice');
            decision = 1;
        case 'wicked', 
            %disp('Wicked');
            decision = 2;            
        case 'random', 
            %disp('Random');
            rr = rand;
            if rr > 0.5
                decision = 1;            
            else
                decision = 2;
            end
        otherwise, 
            disp('Unknown method in "strategy" function.');
            decision = 0;
    end
return

------------------ b2003_04_12_pd.m

% b2003_04_12_pd:  prisoner dilemma 
% Jie Bao 2003-04-12

NumberOfAgent = 2;

% Basic Action
% C - Cooperation 
% D - Defect
NumberOfAction = 2; 
Action = ['CD'] ;

% agent's 
Payoff = ones(NumberOfAgent,NumberOfAction,NumberOfAction); 
% 1st dim: # of agent
% 2nd dim: agent 1's action#
% 3rd dim: agent 2's action#

% Set Payoff
Payoff(1,:,:) = [3,0 ; 5,1];
Payoff(2,:,:) = [3,5 ; 0,1];

% the game
Type1 = 'random';
Type2 = 'random';

TotalPayoff = zeros(1,NumberOfAgent);

for i = 1:2000    
    s1 = strategy(Type1);
    s2 = strategy(Type2);
    
    p1 = Payoff(1,s1,s2);    
    p2 = Payoff(2,s1,s2);    
    TotalPayoff = TotalPayoff + [p1 p2];
end

% show the result
for i = 1: NumberOfAgent
    info = sprintf('Agent %d \"s payoff = %.2f', i , TotalPayoff(i));
    disp(info)
end