Weak Dominance

This lecture covers the difference between weak dominance and strict dominance.

Takeaway Points

  1. Strategy A weakly dominates strategy B if (1) A never provides a lower payoff than B against all combinations of opposing strategies and (2) there exists at least one combination of strategies for which the payoffs for A and B are equal.
  2. This is different than strict dominance because strict dominance requires all payoffs to be strictly greater. There can be no equality with strict dominance.
  3. If you eliminate weakly dominated strategies from a game, an equilibrium in that simplified game will be an equilibrium in the original game as well.
  4. However, this process may delete other equilibria from the game. Unfortunately, there is no way of knowing whether you have removed any equilibria, so you must go back to the original game and check for others.

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