Trigger strategy

{{Short description|Class of strategies employed in a repeated non-cooperative game}} In game theory, a '''trigger strategy''' is any of a class of strategies employed in a repeated non-cooperative game. A player using a trigger strategy initially cooperates but punishes the opponent if a certain level of defection (i.e., the trigger) is observed.

The level of ''punishment'' and the sensitivity of the trigger vary with different trigger strategies.

==Trigger strategies==

*Grim trigger (the punishment continues indefinitely after the other player defects just once) *Tit for tat (the punishment continues as long as the other player defects) *Tit for two tats (a more forgiving variant of tit for tat)

== References == ;Textbooks and general reference texts

* Vives, X. (1999) ''Oligopoly pricing'', MIT Press, Cambridge MA (readable; suitable for advanced undergraduates.) * Tirole, J. (1988) ''The Theory of Industrial Organization'', MIT Press, Cambridge MA (An organized introduction to industrial organization)

;Classical paper on this subject

* Friedman, J. (1971). A non-cooperative equilibrium for supergames, Review of Economic Studies 38, 1–12. (The first formal proof of the Folk theorem (game theory)).

{{DEFAULTSORT:Trigger Strategy}} Category:Non-cooperative games