Hello!

Does the minimum defense frequency (MDF) concept have any validity post flop? Let me elaborate on the question using an example.

Lets assume a heads up game with player A and player B. Player A bets a pot sized bet pre flop. Player B must then defend at least the MDF (50%) in order for player A to not make an immediate profit by betting any hand, so far so good.

Player A then proceed to bet the flop with a pot sized bet and player B must once again defend at least MDF in order for player A to not make an immediate profit by betting any hand. However, this is not a solid argument anymore. Pre flop its a solid argument because its very reasonable to assume that Player A should be folding a part of his range instead of opening every hand with a bet. On the flop however, its not at all unreasonable that player A can make a profit betting every hand, after all, he would also make a profit (on average) checking every hand.

I can think of some special cases where the MDF concept is still valid post flop. One of witch is when player B ONLY defends the MDF amount pre flop, then its a valid argument that he must continue to defend at least MDF on the flop else player B would never fold a hand pre flop because he would make a profit by taking the line of betting pre flop and proceed to betting the flop with any hand. But if player B defends more then MDF pre flop (Which is not at all unreasonable to assume) we can no longer argue that player B must defend at least MDF.

Whats your thoughts? Perhaps there is other reasons that I did not think of that validates the MDF concept (at least as a good approximation) post flop?

MDF is a reasonable tool for estimating your frequencies, but things get complicated very quickly. There is no one-size-fits-all-hard-and-fast rule in poker, unfortunately.

Please elaborate of why its a reasonable tool (post flop). From what I have seen most discussions regarding MDF evolves around certain situations where you should defend more or less then MDF depending on who has an range advantages on certain boards. My problem with MDF (post flop) is more fundamental then that as I cannot see that the basic premise of the concept, i.e. that one has to defend at least MDF else the aggressor can make a profit betting any hand is relevant post flop, except in some special cases as I mentioned in the original post.

If you are new to the concept then try to apply it to dry or not so coordinated boards where you need to defend the required value from your preflop calling range to prevent getting bluffed with any two cards.
I'll try to simplify it, if the flop comes K84r an Villain cbets, you need to build a defending/calling range (e.g. Any king, bunch of PPs, any 8, A4, but also some AJs/ATs for bdsd and bdfd, and hands like 76s, 9Ts with bdfd and any J,6 gives you and oesd on the turn and a 9 or T might be good, and so on) - bc if you always c/f on such a board if you don't have 77+ or a king it's easy for Villain to bluff you with profit. BTW actually look for a c/r range here too but that's another topic.

The more connected a board is, the more you don't need to focus on mdf, if you didn't hit a JT8 board in any reasonable way, just fold.

@Dorian008 Im not sure what you are addressing? The topic of the original post was about the theory behind the concept of MDF and I raised the question if that theory validates it's use post flop. You seem to be talking about ways to implement MDF?

Does nobody use google or the search feature anymore? How many times do people have to keep answering crap about MDF on this forum. I think I’ve seen 5 posts the last week across 2+2 on this.

Please throw a link to any of these post you are talking about, I used both google and the search function on this forum and I am pretty sure I went further back then one week without finding a post answering my question about MDF (which I assume u read??), but I could have missed it.

You get MDF when one playere should be indifferent to bluffing and cheking hands with no eq, but in real poker bluffs do have eq, so we often try to make opponent indifferent to bluffing those (if we can). There are some spot in poker when mdf will be right

Variations on this question have been popping up here for years.

Since I can't be bothered to dig up one of my many rants about it (I'm not a fan of using MDF to build early-street strategies), I think this is as good an answer as any:
The MDF concept has a fair bit of validity on the river, but very little on the earlier streets as far as I'm concerned. Study with a solver and you'll find that folding/continuance frequencies depend on the precise situation and how the ranges play against each other on specific boards.

You open BTN and SB 3bets, BB folds, you call. Flop is KKJr and SB bets 1/4 pot so to meet MDF vs that size you would need to continue 75% of the time (or something close to that im actually bad at math). However the GTO response in this spot is to fold like 50% of the time. So yea MDF pretty useless in any spot except rivers tbh.