Yale / Political Science

Subgame Perfect Equilibrium: Wars of Attrition

By Benjamin Polak | Game Theory Lecture 20 of 24

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Lecture Description

We first play and then analyze wars of attrition; the games that afflict trench warfare, strikes, and businesses in some competitive settings. We find long and damaging fights can occur in class in these games even when the prizes are small in relation to the accumulated costs. These could be caused by irrationality or by players' having other goals like pride or reputation. But we argue that long, costly fights should be expected in these games even if everyone is rational and has standard goals. We show this first in a two-period version of the game and then in a potentially infinite version. There are equilibria in which the game ends fast without a fight, but there are also equilibria that can involve long fights. The only good news is that, the longer the fight and the higher the cost of fighting, the lower is the probability of such a fight.

Course Description

This course is an introduction to game theory and strategic thinking. Ideas such as dominance, backward induction, Nash equilibrium, evolutionary stability, commitment, credibility, asymmetric information, adverse selection, and signaling are discussed and applied to games played in class and to examples drawn from economics, politics, the movies, and elsewhere.

Related Resources

Lecture Transcript, Reading Assignment, Handouts, and Problem Sets

Course Index

  1. Introduction to Game Theory
  2. Putting Yourselves into Other People's Shoes
  3. Iterative Deletion and the Median-Voter Theorem
  4. Best Responses in Soccer and Business Partnerships
  5. Nash Equilibrium
  6. Nash Equilibrium: Dating and Cournot
  7. Nash Equilibrium: Shopping, Standing and Voting on a Line
  8. Nash Equilibrium: Location, Segregation and Randomization
  9. Mixed Strategies in Theory and Tennis
  10. Mixed Strategies in Baseball, Dating and Paying Your Taxes
  11. Evolutionary Stability: Cooperation, Mutation, and Equilibrium
  12. Evolutionary Stability: Social Convention, Aggression, and Cycles
  13. Sequential Games: Moral Hazard, Incentives, and Hungry Lions
  14. Backward Induction: Commitment, Spies, and First-Mover Advantages
  15. Backward Induction: Chess, Strategies, and Credible Threats
  16. Backward Induction: Reputation and Duels
  17. Backward Induction: Ultimatums and Bargaining
  18. Imperfect Information: Information Sets and Sub-Game Perfection
  19. Subgame Perfect Equilibrium: Matchmaking and Strategic Investments
  20. Subgame Perfect Equilibrium: Wars of Attrition
  21. Repeated Games: Cooperation vs the End Game
  22. Repeated Games: Cheating, Punishment, and Outsourcing
  23. Asymmetric Information: Silence, Signaling and Suffering Education
  24. Asymmetric Information: Auctions and the Winner's Curse
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