USBGF OLM 2020-03-25

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Last vote on the OLM:

is Neil Kazaross

score: 0
pip: 160
                         
11 point match
                          pip: 92
score: 6

is USBGF Members
XGID=-bbBCBC-C--Ba-----bcbba---:0:0:1:00:6:0:0:11:10
on roll, cube action?

Analyzed in Rollout No double Double/Take
  Player Winning Chances: 71.64% (G:32.09% B:4.78%) 71.19% (G:32.35% B:6.45%)
  Opponent Winning Chances: 28.36% (G:1.45% B:0.05%) 28.81% (G:1.55% B:0.06%)
  Cubeless Equities +0.767 +1.359
Cubeful Equities
played No double:+0.892 (-0.024)±0.004 (+0.889..+0.896)
xg Double/Take:+0.916±0.008 (+0.908..+0.925)
     Double/Pass:+1.000 (+0.084)
 
Best Cube action: Double / Take
Rollout details
7776 Games rolled with Variance Reduction.
Dice Seed: 65073509
Moves: 4-ply, cube decisions: XG Roller+
 
Double Decision confidence:100.0%
Take Decision confidence:100.0%
Duration: 8 hours 36 minutes

eXtreme Gammon Version: 2.10, MET: Kazaross XG2

USBGF Members vote:
[25] No Double
[18] Double


Grant Hoffman (grant@hoffman.kiwi)
teaches at the Backgammon Learning Center, and can be contacted for lessons via email.

Grant Hoffman recommends: Double

Neil needs 84 pips of timing to have a good 12 backgame. Neil does not have this here. So we should double. Not having those 84 pips is so bad that for money Neil should and would pass.

We are 5 away 11 away. A Gammon on a 2 cube gets us to Crawford but does not win the match for us. Neil would take at this score. If we had one more point and were 4 away 11 away with a doubled Gammon winning the match for us exactly, then Neil would have to pass. Anyone who blindly follows the “Three checkers to clear is a double” rule would not double here, but they would be wrong. The rule is about losing your market. The timing issue means Neil’s position is weaker than it looks.


Kimon Papachristopoulos recommends: Double

Losing the market brings us to 4-away/11-away (Neils match equity around 15% using Neil’s numbers). Winning a doubled gammon brings us to 1-away/11-away Crawford (Neils match equity around 2% estimated because I do not know the table by heart so far down; my memory stops at Crawford 7 away) and losing a redoubled game brings us to 5-away/7-away (Neils match equity around 37% by Neil’s numbers) instead of 5-away/9-away (Neils match equity around 22.33% by Neil’s numbers) in case we don´t double. We can be sure that Neil will not miss his redouble. Let us assume that we will always win a gammon; that Neil will always win a redoubled game. His takepoint that will be (37%-2%):(15%-2%) =35%:13%; more than 30%. Now let us make a corrections on the assumptions that we made to keep math as simple as possible: Neil will surely not always lose a gammon. About the recube, there is no correction necessary because Neil will hardly win a gammon. Thus Neil needs less than “more than 30%” in order to have a take. This is a close call in a backgame with bad but not hopeless timing.

Since it is close and we only can make our opponent make mistakes by giving him a difficult task, we should double.


Today’s vote:

is Neil Kazaross

score: 0
pip: 160
                         
11 point match
                          pip: 92
score: 6

is USBGF Members
XGID=-bbBCBC-C--Ba-----bcbba---:0:0:1:53:6:0:0:11:10
to play 53

eXtreme Gammon Version: 2.10

Comments

  1. Todd Porter Todd Porter says:

    11/8 11/6 is so obvious, I’m wondering if it’s wrong. I can make a case for 11/6 8/5. If he hits with an indirect we have a direct shot, two other points to come in on. You would also have him with three checkers behind your prime, one exposed. Also, having a third checker on the 5 point might play better. more likely to get the gammon if you entice him off, to hit? I’d still play safe.

  2. Jeff Spencer says:

    Recently I’ve been analyzing all my games, especially since I’ve been playing online so much and the transcriptions are automatically saved. I’ve noticed a recurring pattern. I make a LOT of blunders while playing a back game or trying to come in against one. Is there a good resource that I can tap? Something like, “Back Games for Dummies”? I was intrigued by Grant’s knowledge about how many pips in timing Neil needs while playing a 1-2 backgame. Is there a table somewhere that can be memorized?

  3. Eric Stippler says:

    What Phillippe said. ;D

  4. Philippe Salnave says:

    11/8 11/6 no indirect shot and killing sixes.

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