Editing Strategy (game theory) (section)

{{Short description|Complete plan on how a game player will behave in every possible game situation}}
{{other uses of|Strategy}}
In [[game theory]], a '''move''', '''action''', or '''play''' is any one of the options which a player can choose in a setting where the optimal outcome depends ''not only'' on their own actions ''but'' on the actions of others.<ref>[[Ben Polak]] ''Game Theory: Lecture 1 Transcript'' ECON 159, 5 September 2007, [[Open Yale Courses]].</ref> The discipline mainly concerns the action of a player in a game affecting the behavior or actions of other players. Some examples of "games" include chess, bridge, poker, monopoly, diplomacy or battleship.<ref>{{cite book|author-link=Robert Aumann |last=Aumann |first=R. |title=Game Theory. In: Palgrave Macmillan |date=22 March 2017 |publisher=Palgrave Macmillan |location=London |isbn=978-1-349-95121-5}}</ref> 

The term '''strategy''' is typically used to mean a complete [[algorithm]] for playing a game, telling a player what to do for every possible situation. A player's strategy determines the action the player will take at any stage of the game. However, the idea of a strategy is often confused or [[conflate]]d with that of a move or action, because of the correspondence between moves and [[pure strategies]] in [[normal-form game|most game]]s: for any move ''X'', "always play move ''X''" is an example of a valid strategy, and as a result every move can also be considered to be a strategy. Other authors treat strategies as being a different type of thing from actions, and therefore distinct. 

It is helpful to think about a "strategy" as a list of directions, and a "move" as a single turn on the list of directions itself. This strategy is based on the payoff or outcome of each action. The goal of each agent is to consider their payoff based on a competitors action. For example, competitor A can assume competitor B enters the market. From there, Competitor A compares the payoffs they receive by entering and not entering. The next step is to assume Competitor B does not enter and then consider which payoff is better based on if Competitor A chooses to enter or not enter. This technique can identify dominant strategies where a player can identify an action that they can take no matter what the competitor does to try to maximize the payoff.

A '''strategy profile''' (sometimes called a '''strategy combination''') is a set of strategies for all players which fully specifies all actions in a game. A strategy profile must include one and only one strategy for every player.