2. Codeville Revision control computer program – Written by Ross Cohen with some design by Bram Cohen – Use Python – Use merging algorithm called “Codeville merge” – Used by BitTorrent, Mosuki Revision control – Synonym Version control, Source control, (Source) code management (SCM) – The management of changes to stored computer files as Documents, programs, and other information – Most commonly used in software development Team of people may be changing the same files – Identified by a “revision number”, or “revision level” A number or letter code Ex > “revition 1”, “revision 2”, and so on

3. Nash equilibrium vs. Pareto efficiency Both in game theory – Solution concept of a game – Involving two or more players Nash Equilibrium is not Pareto efficient Nash Equilibrium is not Pareto efficient – The player’s payoffs can all be increased Payoffs – Numbers representing the outcomes or motivations of players – Cardinal payoffs Profit, quantity, “utility”, or other continuous measures – Ordinal payoffs Rank the desirability of outcomes

4. Nash equibrium Each player is assumed to know – The equilibrium strategies of the other players In response to a competitor – Choose the best strategy – No gain unilaterally by changing its own strategy Without competitor’s change of strategy No necessarily the best cumulative payoff – The only concern is whether one payoff is larger than another – Ordinal payoffs

5. Pareto efficiency Measure of efficiency In cooperative theory – Without someone else’s loss, no one can gain more The best cumulative payoffs – Cardinal payoffs

6. Example Prisoner’s dilemma – If both prisoners connive, both get 1-year punishments – If both prisoners confess, both get 10-year punishments – If one prisoner confesses & the other connives, 3-year & 15-year punishments, respectively – 4 cases Prisoner 1 Prisoner 2 ConfessConnive ConfessP1 : 10, P2 : 10P1 : 15, P2 : 3 ConniveP1 : 3, P2 : 15P1 : 1, P2 : 1 Nash equilibrium Pareto efficient

7. Reference Wikipedia – http://www.wikipedia.org http://www.wikipedia.org Codeville Nash equilibrium Pareto efficient Game Theory.net – http://www.gametheory.net/dictionary http://www.gametheory.net/dictionary Nash equilibrium Pareto efficient Payoffs Nash equilibrium and Mechanism Design – http://www.sss.ias.edu/publications/papers/econpaper86.pdf http://www.sss.ias.edu/publications/papers/econpaper86.pdf