Regret Minimization in Games and the Development of Champion Multiplayer Computer Poker-Playing Agents

• Author / Creator

  Gibson, Richard G

• Recently, poker has emerged as a popular domain for investigating decision problems under conditions of uncertainty. Unlike traditional games such as checkers and chess, poker exhibits imperfect information, varying utilities, and stochastic events. Because of these complications, decisions at the poker table are more analogous to the decisions faced by humans in everyday life. In this dissertation, we investigate regret minimization in extensive-form games and apply our work in developing champion computer poker agents. Counterfactual Regret Minimization (CFR) is the current state-of-the-art approach to computing capable strategy profiles for large extensive-form games. Our primary focus is to advance our understanding and application of CFR in domains with more than two players. We present four major contributions. First, we provide the first set of theoretical guarantees for CFR when applied to games that are not two-player zero-sum. We prove that in such domains, CFR eliminates strictly dominated plays. In addition, we provide a modification of CFR that is both more efficient and can lead to stronger strategies than were previously possible. Second, we provide new regret bounds for CFR, present three new CFR sampling variants, and demonstrate their efficiency in several different domains. Third, we prove the first set of sufficient conditions that guarantee CFR will minimize regret in games with imperfect recall. Fourth, we generalize three previous game tree decomposition methods, present a new decomposition method, and demonstrate their improvement empirically over standard techniques. Finally, we apply the work in this thesis to construct three-player Texas hold'em agents and enter them into the Annual Computer Poker Competition. Our agents won six out of the seven three-player events that we entered from the 2010, 2011, 2012, and 2013 computer poker competitions.

• Subjects / Keywords

  • Poker
  • Game theory
  • Regret minimization
  • Multi-agent systems
  • Artificial intelligence

• Graduation date

  Spring 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R39P2WF2V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.