Table of Contents
What Is MDF?
The concept of Minimum Defense Frequency (MDF) plays a crucial role in poker, as it helps players ascertain the proportion of their range that should be defended when facing an opponent's bet. hand range This involves deciding how much of your hand range to continue with—whether that means calling or raising—when your opponent puts in a bet.
When to Use MDF?
Before diving into the calculation methods and real-world applications of MDF, it’s vital to revisit the two principal strategies that can be employed to effectively respond to adversaries in poker:
Game Theory Optimal (GTO): This approach emphasizes a strategically sound method that is difficult for opponents to exploit, focusing on specific bet sizing and hand selection to prevent opponents from capitalizing on mistakes.
- Exploitative: In this context, players identify the weaknesses in their opponents' strategies and intentionally vary from GTO principles to counter these flaws, thereby maximizing profits based on their specific opponents’ tendencies.
It's worth noting that most players, outside of high-stakes games, tend to stray from GTO strategies. Many find greater success by adopting an exploitative strategy that targets the weaknesses of the players in their particular games.
Additionally, keep in mind that the MDF concept is mainly applicable in contexts where you lack sufficient reads on your opponent(s) or are unfamiliar with the common behaviors observed among players in your game pool. GTO poker strategy The Minimum Defense Frequency formula helps you relate the size of your opponent's bet and the total pot to the percentage of your hand range you should maintain by calling. The formula is expressed as:
How to Use MDF?
INITIAL POT SIZE / (INITIAL POT SIZE + BET SIZE)
To illustrate, imagine a river scenario in a 200NL live game where the pot totals $150, and your opponent places a bet.
In this situation, you would insert the relevant variables into the formula: all-in for his last $100.
This calculation indicates that regardless of your hand's composition at the river, in order to shield yourself from being exploited by bluffs, you need to call with 60% of your range.
MDF = $150 / ($150 + $100)
MDF = $150 / $250
MDF = 0.6
MDF = 60%
We have prepared a useful chart that simplifies the process of determining what proportion of your range should be defended according to MDF in relation to common bet sizes (as a percentage of the pot):
Basic MDF Chart
Suppose you're engaged in a $0.50/$1.00 online poker game.
MDF Example in Practice
The action comes to a halt with folds until the Button (BTN), who raises to $2.50. The Small Blind (SB) has folded.
On the flop, the cards are 6♠ 4♦ 2♥. You check, and the BTN responds with a bet of $1.50 into a pot of $6.00. You decide to call.
Hero is in BB with K ♥4 ♥ and calls.
Then, the turn shows the 2♣. You check again, and your opponent bets $4.50 into the now $9.00 pot. You call once more.
The river reveals the 7♥. After checking, your opponent bets $13.50 into the $18.00 pot.
Since this bet amounts to 75% of the pot, according to the chart referenced earlier, you would need to proceed with around 57% of your hand range to avoid being taken advantage of.
Should you be calling this river?
Now, we’ll reapply the previously mentioned formula with the example's figures:
MDF = INITIAL POT SIZE / (INITIAL POT SIZE + BET SIZE)
Surprisingly, if you've played optimally until this point, maintaining proper defense, it turns out that a hand like K ♥4 ♥ actually qualifies as a call in this instance.
MDF = $18 / ($18 + $13.50)
MDF = $18 / $31.50
MDF = 0.57
MDF = 57%
(To help visualize the range dynamics and appropriate plays for this river situation, we have compiled all pertinent hand information into a poker simulation.)
All highlighted areas represent different hand combinations that could still fit within your defensible range. The color coding indicates how you should handle these hands. solver program called PioSolver ):
As you can see from the green highlights—representing hands deemed suitable for a call—K ♥4 ♥ is indeed part of your calling range in this scenario.
NOTE: It’s essential to remember that recommending a call here is based on GTO principles relating to MDF. If you're aware of your opponent's habits and recognize they don't bluff frequently, you may find it profitable to consider folding this hand exploitatively.
There are specific cases where the MDF concept may not be applicable.
When to Avoid Using MDF
Against inexperienced players (or those who don't bluff often) : As stated earlier, you can extract more value from these opponents by using exploitable strategies rather than adhering strictly to GTO principles. If it's clear your opponent is betting too often, feel free to call more liberally with a wider array of hands. (You could even establish MDF as your starting point and expand your calling range from there.)
These situations are as follows:
- Likewise, if your opponent only places bets when holding strong cards, then the MDF concept becomes irrelevant. MDF is meant for staying unexploitable against bluffs, thus it loses its significance if your opponent always has strong hands when betting. When defending against continuation bets from out of position on the flop : Given the inherent challenges associated with realizing your equity from the big blind after an open, relying on MDF for defense against continuation bets from out of position is inadvisable. Doing so may lead to a portion of your defense being negatively affected (–EV). bluffing Minimum Defense Frequency (MDF) links your opponent’s bet sizing to the correct actions you should take in many situations (similar to the principle of mutual protection).
Understanding and practicing the MDF concept outside of actual play is crucial, especially after initial exposure. This will refine your ability to assess your entire hand range—an essential aspect of winning poker strategies. You will also start developing a clearer understanding of which hands to carry forward in various contexts, taking into account different board situations and varying bet sizes.
- By establishing a foundational MDF strategy, you will gain insights into how to adeptly adjust your play when looking to effectively counter your opponents’ styles. Even if you choose to diverge from it in practice, opting for a more exploitative strategy than a strict GTO one, you may find that this adjustment yields higher profits against your regular opponents. OOP Matthew Cluff is a poker specialist known for his expertise in 6-Max No Limit Hold’em. He also contributes poker content to various online platforms.
Breaking Down MDF in Summary
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