strategy
Minimum defence frequency (MDF)
Also: MDF, minimum defense frequency
The share of your range you must continue with (call or raise) against a bet so that the opponent cannot profit by bluffing any two cards. MDF = pot ÷ (pot + bet).
Example. You face a €50 bet into a €100 pot; MDF is 100 ÷ 150 ≈ 67%, so folding much more than a third of your hands is exploitable.
Facing a half-pot bet you must defend 67% of your range; against a pot-sized bet, 50%; against a 2x overbet, 33%. MDF is a ceiling on how much you can fold before becoming exploitable, not a target — against players who rarely bluff you should fold far more. It pairs with pot odds, which look at the same bet from the caller's side.