What is the definition of a dominant strategy in game theory?

Conditions

• Must be the best response to all possible actions of the opponent.
• Applies to a specific player in the game.

Reasoning, step by step

1. Identify all possible actions of the opponent.
2. For each opponent action, find the player's best response.
3. Check if the player's best response is the same action for every possible opponent action.
4. If yes, that action is a dominant strategy.

Example

In the example, Mary's best response is always UP, regardless of whether Harley plays UP or DOWN. Therefore, UP is a dominant strategy for Mary.

Common misconceptions

• Confusing a dominant strategy with a Nash equilibrium; a dominant strategy is a property of a single player's action set, while a Nash equilibrium is a property of an outcome.
• Assuming every player in every game has a dominant strategy.

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