On the Existence of Nash Equilibrium in Games with Resource-Bounded Players

Joseph Y. Halpern, Rafael Pass, Daniel Reichman*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


We consider computational games, sequences of games (Formula Presented) where, for all n, (Formula Presented) has the same set of players. Computational games arise in electronic money systems such as Bitcoin, in cryptographic protocols, and in the study of generative adversarial networks in machine learning. Assuming that one-way functions exist, we prove that there is 2-player zero-sum computational game (Formula Presented) such that, for all n, the size of the action space in (Formula Presented) is polynomial in n and the utility function in (Formula Presented) is computable in time polynomial in n, and yet there is no (Formula Presented) -Nash equilibrium if players are restricted to using strategies computable by polynomial-time Turing machines, where we use a notion of Nash equilibrium that is tailored to computational games. We also show that an (Formula Presented) -Nash equilibrium may not exist if players are constrained to perform at most T computational steps in each of the games in the sequence. On the other hand, we show that if players can use arbitrary Turing machines to compute their strategies, then every computational game has an (Formula Presented) -Nash equilibrium. These results may shed light on competitive settings where the availability of more running time or faster algorithms can lead to a “computational arms race”, precluding the existence of equilibrium. They also point to inherent limitations of concepts such as “best response” and Nash equilibrium in games with resource-bounded players.

Original languageEnglish
Title of host publicationAlgorithmic Game Theory - 12th International Symposium, SAGT 2019, Proceedings
EditorsDimitris Fotakis, Evangelos Markakis
Number of pages14
ISBN (Print)9783030304720
StatePublished - 2019
Externally publishedYes
Event12th International Symposium on Algorithmic Game Theory, SAGT 2019 - Athens, Greece
Duration: 30 Sep 20193 Oct 2019

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume11801 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference12th International Symposium on Algorithmic Game Theory, SAGT 2019


  • Bounded rationality
  • Nash equilibrium
  • Turing machines


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