Weak dominance
One strategy never pays less than another and sometimes pays more.
Often misread asDeleting weakly dominated strategies round after round in the way one does with strict dominance, without noticing that the surviving set depends on the order the deletions were done in.
How to see it
Never worse, and sometimes better
A strategy weakly dominates another if it does at least as well against everything the other player might do, and strictly better against at least one thing. That is a real reason to prefer it, but a thinner one, because against some opponents the two options are genuinely identical.
The checkStrict elimination is order-independent, weak elimination is not, so say which order you used and treat the answer as one of several.
Try itFind a game in which a weakly dominated strategy is still part of a Nash equilibrium. If that sounds impossible, you are still treating weak dominance as if it ruled things out the way strict dominance does.
Games that show it
Know these first
Leads on to
Easily confused with
Sources
- Osborne, M. & Rubinstein, A. (1994). MIT Press.
- Myerson, R. (1991). Harvard University Press.