What is the difference between MDF and pot odds??

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What is the difference between MDF and pot odds??

I'm trying to get a beter understanding of the maths in poker and I'm struggling with MDF. To me MDF seems the same as pot odds. But it's obviously not because the formulas are different.

MDF:

pot size / (pot size + bet size)

Pot odds:

(bet size) / (pot size + bet size + call size)

When an opponent bets, I use pot odds and equity to work out "what hands to call with". Which to me is the same as saying "what hands to defend with". What is MDF doing that's different?? Is it ok to not worry about MDF or is it important.

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Steve Paul 18 days ago

In many situations it is not important, but the idea of MDF is something along the lines of "what's the minimum frequency I have to continue such that my opponent's bet isn't automatically profitable?" So if your opponent bets half pot on the river then your MDF is 2/3 per your formula. That means if you call 2/3 of the time, your opponents bluffs will breakeven (ignoring blockers.) So what happens if you call less than 2/3 of the time? In practice probably not much. But if your opponents knows that you only call 60% of the time, then his bluffs make money and he should bet all of his bluffs (assuming you don't notice this and adjust.)

My first ever RIO video (Improving on 1-a) talks a lot about MDF and it's limitations.

tbeckett 17 days ago

But surely what makes me call is what I believe the opponent is betting?? So my calling range is based on what I think the opponent has.

If he's a nit, I should fold most hands, If he bluffs a lot I start calling with with more hands.

Steve Paul 17 days ago

Right, if your opponent is not very good then just ignore MDF. But if your opponent is pretty good and bluffing an appropriate amount, and is likely to exploit you if you fold too much or too little, then there are spots (like facing river bets) where you should be aiming to continue roughly the MDF frequency

tbeckett 16 days ago

Couldn't I just put all his value hands, and bluffs into an equity tool, and just see what hands I can call?? Would that achieve the same thing as MDF?

Steve Paul 16 days ago

The point is you don't actually know his betting range. You can make some assumptions/educated guesses but that's it. The better those guesses are the more you can deviate from what a solver might tell you to do (this guy bluffs too much, so I'm going to call all my bluffcatchers.) But you have to remember that these are assumptions and also that your opponents are not complete idiots. If you always call all your bluffcatchers they will adjust eventually.

Think of MDF as a kind of defence. When you're not really sure how much an opponent is bluffing on the river, you should aim to continue roughly MDF. The more sure you are of your reads the more you deviate.

Brokenstars 18 days ago

Steve Paul's response is great. I'll add that MDF is often very close to the overall folding frequency in many spots for a solver output, but not always as the most important things are what you stated (equity/pot odds). Basically, is it profitable or not to call.

Looking at a toy game can help with understanding this. Pretend you're on the river with nothing but bluff catchers and your opponent has nuts or air and is using a pot sized bet to go all-in. His bluffing frequency in this perfectly polarized spot is equal to the pot odds given to you which achieves indifference (33%) or pot/(bet + pot + call) = 1/3. If his bluffs have 0 pot share when checked, then you make him indifferent to bluffing by calling 50% or at MDF (bet/(pot+bet)). Your call or fold are both 0 EV at equilibrium, but you're doing it at a frequency that makes your opponent indifferent to bluffing more. Deviating from this leads to you potentially getting exploited in that your opponent either always bluffs or never bluffs if you fold more or less than MDF. What really matters, though, is that his check and bet for his bluff have a delta EV of 0 at equilibrium for whatever the constraints are.

There are other toy game examples that might improve your understanding here by Ben sulsky (very old videos) as well as some toy games in the book, "Mathematics of Poker".

MDF is useful as a baseline starting point to get an approximation of what the most you're probably folding for a spot is and the closer the spot is to nuts/air the closer that approximation probably is.

tbeckett 17 days ago

Yeah that's to complicated for me. Thanks for writing it though, I really appreciated it.

To me surely my calling range should be based on his range. If he has loads of bluffs the wider I can call, if he's a nit the more I fold.

Surely I shouldn't be calling 60% of my range against a nit betting half pot

Brokenstars 15 days ago

Yes, that is all correct. Keep in mind, though, that for someone betting half pot you would only fold ~1/3rd of the time, not 40%. Still though you're correct in that if they are underbluffing you just fold all your bluff catchers. If they are overbluffing, then you call all bluff catchers.

HawksWin 17 days ago

A very abstract and simplified way to apply MDF and Pot Odds is to use MDF when betting and rely on Pot Odds when calling.

MDF

Pot is 100, when I bet pot, I need to get folds 50% of the time (not considering ranges, hands, etc.). I bet 100 into 100 and he calls and we lose, -100. Next, I bet 100 into 100 and he folds, we win 100. Therefore, we break even when he folds 50% of the time. I Find it most useful when I am bluffing and looking to get folds. The smaller you bet, the less often it needs to work and the bigger you bet, the more often it needs to work.

Pot Odds

Super important and I would work to get this down to a science.

Naked Nut FD on the flop, guy bets 1/2 pot, you are getting 3:1 odds. You assume you have 9 outs to the flush and you have 3 ace outs (assuming outs are clean). You have roughly 25% equity. You are getting direct odds to call. Now, consider you have naked NFD on the flop but also have a pair, now you have 2 additional outs to trips, now your equity exceeds the odds being offered.

Just play around with an equity calculator that allows range vs range analysis and you can work out the equities and then figure out what size bets you can call.

I made an odds chart that I had open in game back in the day. You can reference it over and over and the numbers will become 2nd nature.

HawksWin 14 days ago

Again, the simplifications I described above are very abstract.

MDF is typically most effective when used on the river.

Imagine you make a pot sized bet 1,000,000 times. In order the meet MDF, your opponent needs to call 1/2 the time or 50% of the time. Again, this is not taking ranges into consideration.

Now, say you make a pot sized bet 1,000,000 times more, but this time he folds 60% of the time. He is not meeting his MDF and is therefore overfolding.

Take it one step further, you make 1,000,000 more bets, but this time you bet 2/3 pot and you still get folds 60% of the time. He is making a massive overfolding error.

Things get much more complicated when you factor in earlier streets, positions, range construction, player type, etc.

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