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ISF – Forming Ranges

Something I like to do, and what I always advocate people who seek poker help from me, is to break down the elements of poker so we can understand concepts behind them and further apply them. I feel like most of the problems with people stuck at low and midstakes is they have tirelessly listened and applied the advice of players who are better then them, but they have no idea why they are doing what they are doing and therefore start having giant leaks in their game, while those who understand can self repair their leaks. Poker is a complex game that very few understand even a little bit. In this article, I’ll breakdown raising preflop, I’ll answer some questions I received in my comment thread.

Preflop we’re going to start from scratch. It’s a simple scenario to breakdown really and all we need is Poker Tracker; we’re UTG, what hands do we want to raise? AA? Sure, it’s the biggest winner in my database UTG. KK-TT? Yeah of course, they are winners as well. AK and AQ/KQ, AJs? 66-99? They are winners too. It sounds simple, but the first step of deciding what hands we want to play preflop is what hands are winning money. However, what surprises me about my database is that UTG I am losing money with AJo and 55-22. This is not an anomaly either, in most PT databases these hands will be losers UTG. So that brings us to our second reason for playing hands preflop: To get action on our bigger hands, in other words metagame. Yet, this is pretty irrelevant at many who are reading this article’s stakes, so you may just want to consider dumping them preflop. Rarely do we see someone have stats on UTG raising % on their PAHUD anyways, so it’s going to be almost impossible to tell how tight we are UTG.

But in many aspects of the game being too tight or too loose in certain spots can be much more obvious, which brings me to the last and less talked about aspects of decision making: To benefit our range. This is very complicated, so I’ll try to simplify it, and there are a few parts of it as well. One of the aspects is simply the second point noted earlier, metagame. We add weaker hands to our range to get action on our bigger hands. We want to choose hands that will play similar to our big hands that are weaker but not too much so. Suited connectors are one of the best options. We can play draws we flop, which in my previous article we saw have stable equity across ranges, fast like our overpairs and sets. The final aspect is to fix holes in our range. This has to do with ISF theorem.

What I just did was forming a range. You can do this process for any part of the game. For those who feel they have significant leaks in their game, try forming a range for yourself in every spot and see where you are making mistakes.

Now to questions asked in my thread.

maybe something about getting reraised on flop/turn/river and what you can extract from betting sizes from your opponents?

Timing tells and bet sizing are extremely underused in poker but can be the best information of all. A simple timing tell is taking time to make a decision, rather than instantly acting. For example our LAGG opponent raises on the BU and we threebet from the blinds with AK. We have been threebetting a lot. Our opponent calls, but we note that he took longer than he normally does to do so. This is pretty obvious strength. He was taking time because he was deciding whether he was going to fourbet or call. So if I flop air, I’m probably not going to continue.

Bet sizing can be a great tool as well. One that comes up for me a lot is when I’m playing HU. Let’s say in a ½ game I raise preflop on the BU to 6 with 444, and a Tagg OOP who is calling OOP about 20% of the time calls (I often have this stat up on PAHUD). The flop comes QT3, two diamonds, he checks, I cbet 8 and he decides to call. Turn is a T spades, which is a bad card for me as a ten is a likely holding for him. We check through. River is a 7, not a diamond and the pot is now 27. Often with a T or a Q you’ll see someone lead here for close to pot, because they don’t feel like a weaker Q is folding so they want to extract maximum. So when your opponent bets something like 18 or 20, I often look them up. In fact, this hand happened to me today and he ended up showing me 65.

In the scenario you mentioned though, getting raised on the flop, turn or river, it’s a lot harder to extract information from bet sizing. What you need to do is make sure you put your opponent on a detailed range every street, and see if that bet size makes sense. When you do this well, you’ll be amazed to what kind There are a few scenarios I can mention as tips though.

Simple scenario of we raised preflop in late position to 8 in a 1/2 game and got called from a LAGG in the blinds. The flop comes J52 two diamonds, we cbet 12. Much of the time if I see a small raise, like to 30, it likely means a hand like J9/JT or air. If you have a tight image, since that range is very weak its exploitable. Simple ISF theorem: We can have JJ-AA, AJ, 55, 22, and he likely doesn’t. Sometimes though this doesn’t mean flush draw, so if you see that same player reraise to 36-40, the likely hood of a flush draw is extremely high, as the only other hands he’s repping is 55 or 22, a small range indeed.

One random bet sizing tell that my friend kingsofcards told me is that if someone raises you but doesn’t leave any room in his stack for a turn or river bet they are often bluffing. I’ve found this to be a very successful tell, so try it out.

On to the next question:

One simple situation that comes up so often that I’ve been thinking about is SB vs BB. We are in BB and SB open raises 3xBB usually.

I think ppl are CALLING way too much and instead should 3bet a huge % of hands bcoz we get inititive and position, 3betting works great against multitabling players, postflop is easy. i dunno whats your most used play since ppl steal % in this spot must be higher than on button.

Position threebetting one of the best moves and hardest move to deal with in poker. Reason being is calling threebets OOP is very often a –EV play, and also simple equity calculations put you at a huge advantage. I won’t go through it all, but I’ll put it simply. We are at 1/2. Many people raise in the CO with anywhere from 28-40% of their hands, which the LAGG in the CO does. We reraise his $8 raise to $25. Let’s say we threebet 15% (Which is no small number) of our hands from the BU to a CO raise. We decide we will reraise over a fourbet with AK, JJ+, which is 3% of hands. That means 1/5th of the time we will stack off to a fourbet. For someone who is raising 30% in the CO, even if he folds 3/4ths the time, which he should be, we are +EV simply on FE. If he decides to call too much we will win money because we have position and equity.

Yet, even if he decides to fourbet light, we still have 8 times our raise left in our stack, and considering we are stacking off 1 in 5 times, even if we’re a slight underdog to his fourbet range we are still +EV. So really the only way to combat this is to raise less hands in the CO. If you didn’t understand the math, it’s not too hard, it may be good for you to try it out for yourself.

(Note: It is extremely +EV in poker to force your opponent to put in a committing bet rather than you, as shown by position threebetting)

As far as SB vs BB goes, it all depends on your opponent. I don’t tend to raise a lot in the SB when folded to unless my opponent is on auto pilot fold. But if your opponent is raising a lot in the SB you can own him by position fourbetting. It is much, much better to raise a ton of hands on the BU rather than the SB.

That’s it for this week, hope it was enjoyable.

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