Part 2 Take or Pass:
from: Christian Liebe-Harkort
As an example we will look at position 594, you are white and
have to decide, whether you should take or pass.
In a regular money game this is an easy take.
For our analysis we will make the same assumptions as in Part
1:
- you play $10 a point
- the rake is 5%, with the winner paying 10%
- At least $80 are at the table
Position 594, Category Bear Off
Roll or Double?
Black vs White
Moneygame: Jacoby and Beaver
added at 3/7/2010 10:22 AM, from admin
Pipcount: 4(0) - 4(0)
Evaluation Level: 7 ply
Winning Chances:
| Player: | 79.94% | 79.94% | 0.00% | 0.00% |
| Opponent: | 20.06% | 20.06% | 0.00% | 0.00% |
Cubeful Equities:
| No Double: | +0.599 | -0.352 |
| Double / Take: | +0.951 | best |
| Double / Drop: | +1.000 | +0.049 |
Best Cube Action: Double / Take
Cubeless Equities:
| No Double: | +0.599 |
| Double: | +1.198 |
Software: eXtreme Gammon Version: 1.12
Calculations without rake
Let's start with the equity for a take when there is no
rake:
|
cube
|
1st roll
|
2nd roll
|
payout
|
$/point
|
total
|
|
4
|
26
|
36
|
-100%
|
$10
|
-$37.440.00
|
|
8
|
10
|
26
|
100%
|
$10
|
$20.800.00
|
|
8
|
10
|
10
|
-100%
|
$10
|
-$8.000.00
|
|
|
|
|
sum
|
-$24.640.00
|
|
|
|
|
equity
|
-$19.01
|
Your equity is $-19.01, exactly the value, the software displays
(+0.951 x -2 x $10)
That means, on average you would loose $19.01 by taking in this
position. Your alternative is to pass the 4 cube and that means
losing two points, $10 each, for a total of $20.
Taking saves you $0.99 on average and is the correct
decision.
Calculations with rake
Now we do the same calculation, with the difference that your
payout is just 90% (100% - 10% rake).
|
cube
|
1st roll
|
2nd roll
|
payout
|
$/point
|
total
|
|
4
|
26
|
36
|
-100%
|
$10
|
-$37.440.00
|
|
8
|
10
|
26
|
90%
|
$10
|
$18.720.00
|
|
8
|
10
|
10
|
-100%
|
$10
|
-$8.000.00
|
|
|
|
|
sum
|
-$26.720.00
|
|
|
|
|
equity
|
-$20.62
|
Your equity for taking is $-20.62.
That means that on average you would loose $20.62 if you take in
this position. Once more, your alternative is to pass the 4 cube
and that means losing two points, $10 each, for a total of $20.
Taking costs you $0.62 on average and is a mistake
(eg:-0.031).
Rake adjusted Take point:
The basic take point of 25% in money games is calculated as
follows:
You compare the equities for pass versus take. If you are
doubled to 2 you can either pass, losing one point on average or
take. The equity for the take is calculated qas follows: Let "p" be
the chance that you win. Then the chance that you don't win is 1-p.
So your equity is:
2p - 2 x (1-p) this can be reduced to 2p -2 + 2p or 4p -
2
So we can take when 4p - 2 > - 1 (= the one point we lose
when we pass) , that transforms to 4p > 1 or p > ¼ or p
> 25%
Please note this formula does not take into account that you
could redouble, so this calculation is only valid for a dead
cube.
No we do the same calculation, but introduce the new variable
"r" that is the rake in percent. So as the winner pays for both
players instead of 1 point he will receive only 1-2r points. We
still lose one point when we pass, but when we take our calculation
looks different:
2p x (1-2r) - 2 x (1-p) = 2p -4pr -2 + 2p = 4p - 4pr - 2
So we should take when 4p - 4pr - 2 > -1 or 4p - 4pr > 1
or p (4 - 4r) > 1 or
p > 1/(4-4r) or p > ¼(1-r)
The following table will give you an idea on how the rake
affects the take point.
|
rake
|
take point
|
|
0.0%
|
25.0%
|
|
1.0%
|
25.3%
|
|
2.0%
|
25.5%
|
|
3.0%
|
25.8%
|
|
4.0%
|
26.0%
|
|
5.0%
|
26.3%
|
|
6.0%
|
26.6%
|
|
7.0%
|
26.9%
|
|
8.0%
|
27.2%
|
|
9.0%
|
27.5%
|
|
10.0%
|
27.8%
|
|
11.0%
|
28.1%
|
|
12.0%
|
28.4%
|
|
13.0%
|
28.7%
|
|
14.0%
|
29.1%
|
|
15.0%
|
29.4%
|
|
16.0%
|
29.8%
|
|
17.0%
|
30.1%
|
|
18.0%
|
30.5%
|
|
19.0%
|
30.9%
|
|
20.0%
|
31.3%
|
|
21.0%
|
31.6%
|
|
22.0%
|
32.1%
|
|
23.0%
|
32.5%
|
|
24.0%
|
32.9%
|
|
25.0%
|
33.3%
|
When you pay rake, your take point is a higher than in a regular money game. The higher the rake, the higher is your take point.
As a general guideline: In close decisions between taking and passing, you should tend towards passing.
updated: Thursday, April 15, 2010