Graphical game theory
In game theory, the common ways to describe a game are the normal form and the extensive form. The graphical form is an alternate compact representation of a game using the interaction among participants.
Consider a game with players with strategies each. We will represent the players as nodes in a graph in which each player has a utility function that depends only on him and his neighbors. As the utility function depends on fewer other players, the graphical representation would be smaller.
Formal definition
A graphical game is represented by a graph , in which each player is represented by a node, and there is an edge between two nodes and iff their utility functions are dependent on the strategy which the other player will choose. Each node in has a function , where is the degree of vertex . specifies the utility of player as a function of his strategy as well as those of his neighbors.
The size of the game's representation
For a general players game, in which each player has possible strategies, the size of a normal form representation would be . The size of the graphical representation for this game is where is the maximal node degree in the graph. If , then the graphical game representation is much smaller.
An example
In case where each player's utility function depends only on one other player:
- The graphical form of the described game
The maximal degree of the graph is 1, and the game can be described as functions (tables) of size . So, the total size of the input will be .
Nash equilibrium
Finding Nash equilibrium in a game takes exponential time in the size of the representation. If the graphical representation of the game is a tree, we can find the equilibrium in polynomial time. In the general case, where the maximal degree of a node is 3 or more, the problem is NP-complete.
Further reading
- Michael Kearns (2007) "Graphical Games". In Vazirani, Vijay V.; Nisan, Noam; Roughgarden, Tim; Tardos, Éva (2007). Algorithmic Game Theory (PDF). Cambridge, UK: Cambridge University Press. ISBN 0-521-87282-0.
- Michael Kearns, Michael L. Littman and Satinder Singh (2001) "Graphical Models for Game Theory".
- v
- t
- e
- Congestion game
- Cooperative game
- Determinacy
- Escalation of commitment
- Extensive-form game
- First-player and second-player win
- Game complexity
- Graphical game
- Hierarchy of beliefs
- Information set
- Normal-form game
- Preference
- Sequential game
- Simultaneous game
- Simultaneous action selection
- Solved game
- Succinct game
- Mechanism design
concepts
- Bayes correlated equilibrium
- Bayesian Nash equilibrium
- Berge equilibrium
- Core
- Correlated equilibrium
- Coalition-proof Nash equilibrium
- Epsilon-equilibrium
- Evolutionarily stable strategy
- Gibbs equilibrium
- Mertens-stable equilibrium
- Markov perfect equilibrium
- Nash equilibrium
- Pareto efficiency
- Perfect Bayesian equilibrium
- Proper equilibrium
- Quantal response equilibrium
- Quasi-perfect equilibrium
- Risk dominance
- Satisfaction equilibrium
- Self-confirming equilibrium
- Sequential equilibrium
- Shapley value
- Strong Nash equilibrium
- Subgame perfection
- Trembling hand equilibrium
of games
- Go
- Chess
- Infinite chess
- Checkers
- All-pay auction
- Prisoner's dilemma
- Gift-exchange game
- Optional prisoner's dilemma
- Traveler's dilemma
- Coordination game
- Chicken
- Centipede game
- Lewis signaling game
- Volunteer's dilemma
- Dollar auction
- Battle of the sexes
- Stag hunt
- Matching pennies
- Ultimatum game
- Electronic mail game
- Rock paper scissors
- Pirate game
- Dictator game
- Public goods game
- Blotto game
- War of attrition
- El Farol Bar problem
- Fair division
- Fair cake-cutting
- Bertrand competition
- Cournot competition
- Stackelberg competition
- Deadlock
- Diner's dilemma
- Guess 2/3 of the average
- Kuhn poker
- Nash bargaining game
- Induction puzzles
- Trust game
- Princess and monster game
- Rendezvous problem
- Aumann's agreement theorem
- Folk theorem
- Minimax theorem
- Nash's theorem
- Negamax theorem
- Purification theorem
- Revelation principle
- Sprague–Grundy theorem
- Zermelo's theorem
figures
- Albert W. Tucker
- Amos Tversky
- Antoine Augustin Cournot
- Ariel Rubinstein
- Claude Shannon
- Daniel Kahneman
- David K. Levine
- David M. Kreps
- Donald B. Gillies
- Drew Fudenberg
- Eric Maskin
- Harold W. Kuhn
- Herbert Simon
- Hervé Moulin
- John Conway
- Jean Tirole
- Jean-François Mertens
- Jennifer Tour Chayes
- John Harsanyi
- John Maynard Smith
- John Nash
- John von Neumann
- Kenneth Arrow
- Kenneth Binmore
- Leonid Hurwicz
- Lloyd Shapley
- Melvin Dresher
- Merrill M. Flood
- Olga Bondareva
- Oskar Morgenstern
- Paul Milgrom
- Peyton Young
- Reinhard Selten
- Robert Axelrod
- Robert Aumann
- Robert B. Wilson
- Roger Myerson
- Samuel Bowles
- Suzanne Scotchmer
- Thomas Schelling
- William Vickrey