NLHTP#18 The Sklansky-Chubukov Rankings&When and When Not to Use Them

[wallenborn]

The Sklansky-Chubukov Rankings

You are in the small blind in a $1-$2 game. It is folded to you. Your opponent plays statistically perfect poker. Accidentally, you reveal your hand to your opponent. What do you do now? Well, with aces you'd raise, picking up the blinds almost always. With kings, you could still raise, but your opponent would call you with aces and win most of these hands. Since he can bluff you here, if you raise, you might as well raise all-in. That leads to a different formulation of the question: What is the largest stack you could move all-in with, even if your opponent knew your hand. Or even differently: How large does the effective stack size have to be to make folding better than pushing? This size is called your hand's Sklansky-Chubukov number.

(The number is occasionally called the Sklansky-Karlson number, karlson being Viktor Chubukov's user name on 2+2. Here is the original thread.)

As it turns out, some of these numbers are surprisingly large. Of course it is no surprise that you can move in with AK and an M of 110, but for example JTs has a SC-number of $36. So if your M is 12, shoving is better than folding.

There are two major types of hands:

[img]/images/graemlins/spade.gif[/img] Robust hands can be called profitably by a large number of hands, but they don't fare too badly against those hands on the whole.
[img]/images/graemlins/spade.gif[/img] Vulnerable hands can't be called very often, but when they are called, they are significant underdogs.

At the table, your opponent of course does not know your actual hand, he has to put you on a range. The correct calling range against a vulnerable hand is tight and rather well defined, so it is easier for your opponent to call or fold correctly if you move in with a vulnerable hand. If you move in with a robust hand, it is more difficult for your opponent make the correct decision.

For example, A3o and 22 both have a S-C-number of $48. Against A3o your opponent should call with AKo and fold T7s. Against 22 your opponent should fold AKo and call with T7s. Of course your opponent doesn't know your cards, he has to put you on a range and adjust his calling range accordingly. His calling range will much more likely include AKo than T7s. So against an all-in with 22, your opponent might fold T7s incorrectly or call with AKo incorrectly.

[ QUOTE ]
Sklansky-Chubukov numbers always underestimate the real move-in power of a hand. But they underestimate the power of robust hands more than vulnerable ones.

[/ QUOTE ]

Robust hands include

[img]/images/graemlins/heart.gif[/img] Suited connectors
[img]/images/graemlins/heart.gif[/img] Pocket pairs


When to (and When Not to) Use the Sklansky-Chubukov Rankings

Adjusting for an Ante: if you divide the S-C number by three, you convert them into numbers in terms of whats in the pot initially.

The best hands for moving in: Moving in is most attractive when S-C proves that doing so is better than folding and you don't have a good reason to play your hand a different way. For example, if you are out of position, against a good, aggressive opponent, and you are looking at a hand that is weak except for its showdown value, say K4o. Then you shouldn't try to play poker. If stacks are deep, fold. If stacks are shallow, move all-in.

Exceptions: There are cases where you should fold despite S-C telling you not to. In a tournament with a very weak and and a very short stack, for example, you should not shove a weak hand if you can see the next couple of hands for free.

Moving in with "Too Many" Chips: With a robust hand, you can move in with more than the S-C number of chips, because your opponent is likey to call or fold incorrectly.

Don't move in with hands that "Play Well" S-C tells you when moving in is better than folding. But it doesn't tell you when moving in is the best move. With a hand that plays well, especially in position, you should play normal poker instead.