Editing Game theory (section)

=== Bayesian game ===
{{main|Bayesian game}}
One of the assumptions of the Nash equilibrium is that every player has correct beliefs about the actions of the other players. However, there are many situations in game theory where participants do not fully understand the characteristics of their opponents. Negotiators may be unaware of their opponent's valuation of the object of negotiation, companies may be unaware of their opponent's cost functions, combatants may be unaware of their opponent's strengths, and jurors may be unaware of their colleague's interpretation of the evidence at trial. In some cases, participants may know the character of their opponent well, but may not know how well their opponent knows his or her own character.<ref>{{Cite book|last=Osborne|first=Martin J.|title=An Introduction to Game Theory|publisher=Oxford University Press|year=2000|pages=271–272}}</ref>

[[Bayesian game]] means a strategic game with incomplete information. For a strategic game, decision makers are players, and every player has a group of actions. A core part of the imperfect information specification is the set of states. Every state completely describes a collection of characteristics relevant to the player such as their preferences and details about them. There must be a state for every set of features that some player believes may exist.<ref>{{Cite book|last=Osborne|first=Martin J|title=An Introduction to Game Theory|publisher=Oxford University Press|year=2020|pages=271–277}}</ref>
[[File:An_example_of_diagram.jpg|thumb|Example of a Bayesian game]]
For example, where Player 1 is unsure whether Player 2 would rather date her or get away from her, while Player 2 understands Player 1's preferences as before. To be specific, supposing that Player 1 believes that Player 2 wants to date her under a probability of 1/2 and get away from her under a probability of 1/2 (this evaluation comes from Player 1's experience probably: she faces players who want to date her half of the time in such a case and players who want to avoid her half of the time). Due to the probability involved, the analysis  of this situation requires to understand the player's preference for the draw, even though people are only interested in pure strategic equilibrium.