Imperfect information
At least one player has to choose without knowing everything that has already happened.
Often misread asThinking imperfect information means the players are unsure about payoffs or probabilities, rather than unsure about what has already happened.
How to see it
You have to move without knowing where you are
In a game of imperfect information a player can be at a point in the game without knowing which point it is, because something earlier was hidden from them. Simultaneous moves are the simplest case: you choose without having seen their choice.
The checkUncertainty about the structure of the game is incomplete information; imperfect information is uncertainty about play so far.
Try itDraw rock paper scissors as a tree with one player moving first. That is a perfectly fair representation of a simultaneous game, and the thing that makes it fair is the second player's inability to tell the three nodes apart.
Games that show it
Know these first
Leads on to
Easily confused with
Sources
- Kuhn, H. (1953). In Kuhn, H. & Tucker, A. (eds), Contributions to the Theory of Games, Volume II, Annals of Mathematics Studies 28, Princeton University Press, 193-216.
- Fudenberg, D. & Tirole, J. (1991). MIT Press.