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Open Access Publications from the University of California

Essays on Pure and Applied Game Theory

  • Author(s): Chang, Jen-Wen
  • Advisor(s): Obara, Ichiro
  • et al.

In my dissertation, I provide two models of joint contribution games that are relevant to the phenomenon of crowdfunding. I also provide a characterization of Bayes Nash equilibrium.

In the first chapter I build a model of crowdfunding. An entrepreneur finances her project with common value via crowdfunding. She chooses a funding mechanism (fixed or flexible), a price, and a funding goal. Under fixed funding money is refunded if the goal is not met; under flexible funding the entrepreneur keeps the money. Backers observe signals about the value and decide whether to contribute or postpone purchase to the retail stage. The optimal crowdfunding campaign is characterized. When the entrepreneur has commitment power, fixed funding generates more revenue than flexible funding. When the entrepreneur has no commitment power, fixed funding serves as a commitment device to eliminate moral hazard

In the second chapter I consider a dynamic contribution game under two regimes. The first regime is that all but the last rounds are cheap talk, the other is that in all rounds contribution is sunk. With binary contribution levels and a continuum of types we show that one of the monotone equilibria in the first regime implements the ex-post efficient and ex-post individually rational allocation when the cheap talk period is long enough. In contrast, when commitment is required, no equilibria achieves the same allocation. However, with a continuum of contribution levels, all equilibria of the contribution game with cheap talk will be the same as a one-shot game with no cheap talk, due to severe free riding. In this case, dynamic contribution with commitment provides credibility and can significantly improve efficiency.

In the third chapter, coauthored with Ichiro Obara, we prove the following characterization regarding types and Bayes equilibrium actions they play across games: Given any two types in any two countable type spaces, if for all finite games, the two types have the same pure Bayes Nash equilibrium action, then there exists a bijective belief morphism between them. As an application, our result implies that the universal space for Bayes Nash equilibrium that retains non-redundancy does not exist.

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