Transcript slides - Courses

Computer-Mediated
Communication
Iterated Prisoner’s Dilemma
Coye Cheshire & Andrew Fiore
// April 6, 2016
Strategizing in repeated PD games

Consider two individuals
who interact repeatedly
over time
1)
2)
3)
4)
4/6/2016
No mechanisms for
enforceable commitments.
No way to be sure what the
other will do on each ‘turn’.
No way to eliminate the
other player or leave the
interaction.
No way to change the other
player’s payoffs.
What strategy might
you use if you had to
play this game over and
over again with others?
Always Cooperate?
Always Defect?
Something more
complicated, perhaps
using past behavior?
Computer-Mediated Communication — Cheshire & Fiore
1
Coop
Defect
Coop
3,3
0,5
Defect
5,0
1,1
CCCCCCCCC…
versus
DDDDDDDDD…
4/6/2016
Computer-Mediated Communication — Cheshire & Fiore
2
PD tournament
 Round-robin format
 Each strategy competes one-on-one with every
other strategy and itself




Strategy with the most total points wins
Number of turns per game unknown
Other strategies unknown
No persistent memory across games
4/6/2016
Computer-Mediated Communication — Cheshire & Fiore
3
Writing your strategy
 Work in groups of 2–5 people
 Need at least one person who knows Java
 Need a laptop with a working JDK installation
 IPDLX open-source package
 Moves represented as doubles
 COOPERATE = 1.0, DEFECT = 0.0
 Can return fractional values; system will round them
 History of your moves, opponent’s moves
available — see handout
4/6/2016
Computer-Mediated Communication — Cheshire & Fiore
4
Time for strategizing…
4/6/2016
Computer-Mediated Communication — Cheshire & Fiore
5
Tournament time!
4/6/2016
Computer-Mediated Communication — Cheshire & Fiore
6