Game form

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In game theory and related fields, a game form, game frame, ruleset, or outcome function is the set of rules that govern a game and determine its outcome based on each player's choices. A game form differs from a game in that it does not stipulate the utilities or payoffs for each agent. [1]

Mathematically, a game form can be defined as a mapping going from an actionspace [2] [3] —which describes all the possible moves a player can make—to an outcome space. The action space is also often called a message space when the actions consist of providing information about beliefs or preferences, in which case it is called a direct mechanism. [3] For example, an electoral system is a game form mapping a message space consisting of ballots to a winning candidate (the outcome). [1] Similarly, an auction is a game form that takes each bidder's price and maps them to both a winner and a set of payments by the bidders.

Often, a game form is a set of rules or institutions designed to implement some normative goal (called a social choice function), by motivating agents to act in a particular way through an appropriate choice of incentives. Then, the game form is called an implementation or mechanism . This approach is widely used in the study of auctions and electoral systems. [4]

The social choice function represents the desired outcome or goal of the game, such as maximizing social welfare or achieving a fair allocation of resources. The mechanism designer's task is to design the game form in such a way that when each player plays their best response (i.e. behaves strategically), the resulting equilibrium implements the desired social choice function.

References

  1. 1 2 Gibbard, Allan (1978). "Straightforwardness of Game Forms with Lotteries as Outcomes". Econometrica. 46 (3): 595–614. doi:10.2307/1914235. hdl: 10419/220562 . ISSN   0012-9682. JSTOR   1914235.
  2. Roth, Benjamin N.; Shorrer, Ran I. (March 2015). "Mechanism Design in the Presence of a Pre-Existing Game". Working Paper.
  3. 1 2 Blumrosen, Liad; Feldman, Michal (2013-11-01). "Mechanism design with a restricted action space". Games and Economic Behavior. 82: 424–443. doi:10.1016/j.geb.2013.03.005. ISSN   0899-8256.
  4. Ozdaglar, Asu. "Game Theory with Engineering Applications" (PDF). Archived (PDF) from the original on 2024-06-29.