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Subgame Perfect Equilibrium: Matchmaking and Strategic Investments

By Benjamin Polak - Yale
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Lecture Description

We analyze three games using our new solution concept, subgame perfect equilibrium (SPE). The first game involves players' trusting that others will not make mistakes. It has three Nash equilibria but only one is consistent with backward induction. We show the other two Nash equilibria are not subgame perfect: each fails to induce Nash in a subgame. The second game involves a matchmaker sending a couple on a date. There are three Nash equilibria in the dating subgame. We construct three corresponding subgame perfect equilibria of the whole game by rolling back each of the equilibrium payoffs from the subgame. Finally, we analyze a game in which a firm has to decide whether to invest in a machine that will reduce its costs of production. We learn that the strategic effects of this decision--its effect on the choices of other competing firms--can be large, and if we ignore them we will make mistakes.

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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