Minimum defence frequency
also called MDF
The minimum defence frequency is the share of your range you have to continue with against a bet so that a bluff with any two cards would not make money by itself.
The sum uses only the bet size. Divide the pot by the pot plus the bet: against a bet of half the pot that is 100 divided by 150, so 66.7%, and against a pot sized bet it is 50%.
It is a ceiling on how much you can fold, not a rule about how much you should call. Against an opponent who never bluffs, folding more than this is correct and loses nothing, because the number only protects you against a bluff that could be any hand.
an example
your cards
board
The pot is 100 and your opponent bets 50 on the river. To stop a pure bluff from printing money you have to continue with two thirds of your range, and a pair of eights that beats every missed draw is part of the range that has to do it.
This example is made up. The real one is in your own hand history: find minimum defence frequency in your own hands and see how often it came up and what it cost you.
related terms
Pot odds
Pot odds are the price you are offered on a call: what you have to put in compared with what the pot would be worth to y ...
GTO
Game theory optimal play, usually shortened to GTO, means playing a strategy so balanced that no counter strategy can be ...
Bluff catcher
A bluff catcher is a hand that beats everything your opponent could be bluffing with and loses to everything they would ...
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Knowing the word is not the same as seeing it.
Forty hands against a bot, no account, and your own hand history at the end.