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April 28, 2015

Take Process

My recent post on the Doubling process has proved popular. It has quickly jumped to my #2 most read entry. Here is the follow up on the Take process.

Note the below does not reflect my current process. Rather, this is how top players supposedly approach a take decision.

For Money:

Adjusted Take Point = (22%) + (Opponent's Net Gammons * 1/2)

For Match: **

Adjusted Take Point = (your Take Point at this score) + [ (Opponent's net Gammons) * (opponent's gammon value at this score)]

** technically it would be (your opponent's gammons * his gammon value - your gammons * your gammon value).  As your gammons are typically small I don't see this extra mental effort as worth the accuracy.

Here are an example.

Cube action? As Player 2 (black) how did you decide on take or pass?

is Player 2

score: 0
pip: 163
Unlimited Game
Jacoby Beaver
pip: 141
score: 0

is Player 1
on roll, cube action?

Analyzed in XG Roller++ No double Double/Take
  Player Winning Chances: 74.18% (G:22.27% B:1.33%) 74.51% (G:23.04% B:1.34%)
  Opponent Winning Chances: 25.82% (G:4.78% B:0.14%) 25.49% (G:4.79% B:0.13%)
  Cubeless Equities +0.670 +1.370
Cubeful Equities
No double:+0.936 (-0.064)
Double/Take:+1.187 (+0.187)
Best Cube action: Double / Pass
eXtreme Gammon Version: 2.10

Using the method, you estimate your opponent's gammons and your gammons,  If you were able to correctly guess 22% for opponent and 5% for you then the net gammon loss is 17.5%.  Add half of this to 22% to get an adjusted takepoint of 29.5%.  Now you look at the position as Black and reckon, do I win this game more or less than 29.5%.  If yes, Take,  If no, Drop.

I have to admit that I typically don't do this as estimating gammons is tough.  It's also hard to then look at the position and figure out what 29.5% looks like.  But hey kids, if you want to play like the pro's this is the way to go!


Here is another example, showing match play considerations.

This is the position after 43 Split, 33 Attack and Dance. You trail 5 away 4 away and are being doubled?
Take or Drop?

is Player 2

score: 3
pip: 165
7 point match
pip: 155
score: 2

is Player 1
on roll, cube action?

Analyzed in XG Roller++ No double Double/Take
  Player Winning Chances: 67.40% (G:29.03% B:1.67%) 67.31% (G:29.81% B:1.67%)
  Opponent Winning Chances: 32.60% (G:6.86% B:0.30%) 32.69% (G:7.02% B:0.32%)
  Cubeless Equities +0.558 +1.352
Cubeful Equities
No double:+0.858 (-0.142)
Double/Take:+1.085 (+0.085)
Best Cube action: Double / Pass
eXtreme Gammon Version: 2.10, MET: Kazaross XG2

If you knew this was a close take for money than you might reason that an elevated gammon value makes this dangerous and is probably a pass.  Likely how I would approach such a position.

Using the take process:

Estimate 29% gammons for opponent and 7% gammons for you or 22% net gammons lost.
Approximate opponent's gammon value as .80
and approximate your takepoint at 5 away 4 away as 24.5%

Recall: adj TP = (TP at this score) + (Net gammons lost * Opponent's gammon value)

Adj TP = 24.5 + (22 * .8) or about 42%

Then the question is: Do you win this position 42% of the time?
If yes, Take.
If no, Drop.


If you like this approach, let me recommend you create something like the below in Excel.  Using the above approach, you can estimate whether position is a take or drop at various scores.  In other words, what impact does the match score have on this position compared to a money game?

Numbers in green and red refer to the size of the take or pass.

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