Game ISD

This app helps you practice the iterated elimination of strictly dominated strategies (Iterated Strict Dominance) in two-person normal form games.

When the procedure leads to a unique outcome, it is the game's unique Nash equilibrium. Otherwise (in two-person games) it reduces the players' strategy sets to their rationalizable strategies (strategies consistent with common knowledge of rationality). You will see that in certain games mixed strategies may be needed to eliminate a dominated pure strategy. Another interesting thing to note (and practice) is that the order of elimination makes no difference as to which strategies survive iterated strict dominance. There are over a dozen pre-set games and you can also set up your own payoff matrix.

How to use the app: First, select a game. Then click on the label of a strategy of one of the players; it will be highlighted in red, indicating it is a candidate for elimination. Then select one or more strategies in order to check if they (or their mix) dominate it. (These strategies will be highlighted in green.) The probability weight of the most recently selected "green" strategy can be adjusted by a [-/+] button. If the "red" strategy is indeed dominated by the "green" ones then pressing the red [X] button eliminates it. Do this iteratively (for both players) until no more dominated strategy can be found.

Detailed Help is available within the app (see the Help button in the top right corner). Have fun!