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View Full Version : Flop all-in calculations


Supern
07-10-2005, 07:01 PM
Let's say you have a flushdraw with 2 OC's with: AK/images/graemlins/diamond.gif.
Flop is: 9/images/graemlins/diamond.gif 8/images/graemlins/diamond.gif 2/images/graemlins/club.gif.

You semibluff bet and opponent raises all-in.
Lets say the pot is $19 and you have to call is another $10.

That means you have to win 34% of the time to break even.
If he has TP: T9o you win 53% of the time.
If he has top two: 98o you win 31% of the time.
If he has a set: 99 you win 25% of the time.
So far so good.

How do you weight these possibilites when considering the call?
I include the chance of him bluffing by increasing the chance of him having TP (by 5%).

If I think OP is passive I would use TP-15%, TopTwo-20%, Set-65% and get:
15%*53% + 20%*31% + 65%*25% = 29%

Meaning I have to win 29% of the time -> fold.

If I think OP is aggresive I would use TP-40%, TopTwo-40%, Set-20% and get:
40%*53% + 40%*31% + 25%*25% = 35%

This time I win 35% of the time so I might consider a call.

Is this the way to think about it?
What I am interested to know is the weights I use is ok for making an estimate. How conservative are you guys use at these occations? A draw against a made hand.

AaronBrown
07-11-2005, 03:04 PM
Your basic approach is right, but I would add two more pieces of information. You're looking only at why he went all in. You should also consider the probabilities of being dealt the various hands, and the probability he would have played them pre-flop.

There are 9 ways to have a set, and with a middle or low pair, depending on the player, he would probably call but not raise preflop.

There are 27 ways to have two pair, but these are all terrible hands preflop. If you're willing to assume he bet on one of these preflop, you certainly have to assume he would have bet on anything, meaning that he's likely to have gone all-in with garbage. Therefore, I would downweight this possibility quite a bit.

A pair with an Ace or King could happen 54 ways, and might be a likely call preflop.