Setting up camp in his homeboard? - Backgammon Forum - Discuss Backgammon Strategy, Clubs and Books

Al Mirpuri · 05-25-2012, 07:23 PM

Sorry for no snapshot.

It is a five pointer: I am winning 4-0. It is the Crawford game.

I was bearing in and had him on the bar. We both have five point homeboards.

He hit a fly shot and I danced. He got to his 13pt.

All our checkers apart from mine on the bar and his on his 13pt are spread over our homeboards.

I roll 4-3 and come in on his 4pt. I decide not to run out with the three but play a spare man in my homeboard.

However, I am still subject to a direct hit as he has a spare on his 5 pt and he could roll a small double and switch points.

Was this correct for both money and match play or was it wrong?

TomCowley · 05-25-2012, 07:50 PM

If the race is basically hopeless now, sit there and hope for a miracle hit, but if it's remotely competitive, run. As far as cash/match, I can't see any situation where he has access to the cube, you want to stay back, and it isn't double/drop as soon as you move, so that's kind of irrelevant.

Al Mirpuri · 05-25-2012, 07:55 PM

Quote:

Originally Posted by TomCowley

If the race is basically hopeless now, sit there and hope for a miracle hit, but if it's remotely competitive, run. As far as cash/match, I can't see any situation where he has access to the cube, you want to stay back, and it isn't double/drop as soon as you move, so that's kind of irrelevant.

Thanks for your post Tom.

My thought was that if I run into his outer board then he gets a direct hit from his 13pt which would increase his racing advantage (which was mediumish) as he puts me back on the bar and brings his checker nearer to home.

As it stood he could not close out his board and I rather hoped that maybe I get the direct shot on his next roll.

Alpha Fish · 05-26-2012, 12:55 PM

it depends mainly on your distribution: if your 5-point board is 6-2 prime - stay, 5-1 prime - run, and anything in between you can pretty much flip a coin

Taper_Mike · 05-26-2012, 03:02 PM

Al, it is hard to follow your description. Would you mind doing one of the following?

Post an ID from either GnuBg or XG.
Post a link to a GABBI board.
Post an ASCII board as “code.”

GABBI has is problems, but is still the easiest way to post a board diagram. The regular GABBI site only works with GnuBg IDs in the old style (no text, PositionID and MatchID separated only by a colon). Here is a GABBI link that works when you paste an XGID.

GABBI Site for XGID
http://www.backgammonaustralia.org/gabbi0611.php

My best guess for the locations of spares in your position is the following.

Code:

GNUBG Position ID: d+cGBAB2dwcAQA   Match ID: 8AmuAAAAIAAE
XGID=--BCCCC-----a------bc-cccA:0:0:1:43:4:0:1:5:10


     24 23 22 21 20 19      18 17 16 15 14 13    Player O
    -------------------------------------------
    | O  O  O     O  O |   |                  |  Score : 0
    | O  O  O     O  O |   |                  |  Pips  : 58
    | O  O  O     O    |   |                  |
    |                  |   |                  |
    |                  |   |                  |
    |                  |BAR|                  |v 5-point match, Crawford
    |                  |   |                  |
    |                  |   |                  |
    |       X  X  X  X |   |                  |
    |    X  X  X  X  X |   |                  |  Pips  : 83
    |    X  X  X  X  X | X |                O |  Score : 4
    -------------------------------------------
      1  2  3  4  5  6       7  8  9 10 11 12    Player X


X to play 4-3.

TomCowley · 05-26-2012, 04:06 PM

Quote:

Originally Posted by Alpha Fish

it depends mainly on your distribution: if your 5-point board is 6-2 prime - stay, 5-1 prime - run, and anything in between you can pretty much flip a coin

I set up a few in between positions with fairly bad races and it seemed to want to run until the race got a bit worse than the double/drop pure race pipcount, although it was never a huge edge to running. With decent races, the more palatable the race, the more it liked running. You're right about the 6-2 prime though, it always wants to stay in that case.

Al Mirpuri · 05-26-2012, 07:02 PM

I actually rolled 4-3 not 5-4 (just very thankful to have been able to follow the sticky). I enter and then move from my 4pt.

Taper_Mike · 05-26-2012, 08:49 PM

Thanks for posting the board diagram. It is a big help.

Code:

GnuBG ID: d/MGBADv3AYAQA:8ImxAAAAIAAA
XGID=-DC-CBB-----a------bd-bccA:0:0:1:34:4:0:1:5:8

After you play this 43, your opponent will be on roll, up 2 only pips in the raw pip count. In this kind of close race, your opponent will often hit loose in his inner board. When he does, you are only 30% to hit back. If your opponent does not hit loose, then your racing chances are closer to 35%.

Because the race is still so close, your opponent will hit inside with any 1 or 9 except 61. The difference in the number of return shots is not enough to justify hurting your race by piling another checker on the 1pt. Only eight rolls, 41 51 54 and 63, cause your opponent to leave a blot on the 21pt. And even when you hit that blot, your opponent is 30% to enter on your 3pt on the first try.

Here is an typical rollout where I have given your opponent the roll of 41:

Code:

GnuBG ID: 39kGAAR38wYEAA:sAGmAAAAIAAA
XGID=-EC-BBB-----a------bdAbcc-:0:0:-1:41:4:0:1:5:8
 
Score is X:4 O:0 5 pt.(s) match.
Pip count  X: 62  O: 60 X-O: 4-0/5 Crawford
Cube: 1
O to play 41

    1. Rollout¹    13/9 5/4*                    eq:+0.4513
      Player:   72.49% (G:1.45% B:0.02%)
      Opponent: 27.51% (G:2.04% B:0.00%)
      Confidence: ±0.0008 (+0.4505..+0.4521) - [100.0%]
      Duration: 43.9 seconds

    2. Rollout¹    5/1 5/4*                     eq:+0.3333 (-0.1180)
      Player:   66.63% (G:0.80% B:0.01%)
      Opponent: 33.37% (G:1.89% B:0.01%)
      Confidence: ±0.0010 (+0.3323..+0.3343) - [0.0%]
      Duration: 48.4 seconds

    3. Rollout¹    13/12 5/1                    eq:+0.2207 (-0.2306)
      Player:   61.03% (G:0.16% B:0.00%)
      Opponent: 38.97% (G:0.13% B:0.00%)
      Confidence: ±0.0006 (+0.2201..+0.2212) - [0.0%]
      Duration: 15.6 seconds

    4. Rollout¹    5/1 2/1                      eq:+0.1877 (-0.2636)
      Player:   59.38% (G:0.20% B:0.00%)
      Opponent: 40.62% (G:0.11% B:0.00%)
      Confidence: ±0.0007 (+0.1870..+0.1884) - [0.0%]
      Duration: 19.5 seconds


¹  5184 Games rolled with Variance Reduction.
   Dice Seed: 5800019
   Moves: 3-ply, cube decisions: XG Roller


eXtreme Gammon Version: 2.03, MET: Kazaross XG2

TomCowley · 05-26-2012, 08:52 PM

That race is ok, GNU strongly favors running (wins 4% more games).

Al Mirpuri · 05-26-2012, 09:01 PM

Thanks Taper_Mike and TomCowley for your help.

Thanks Taper_Mike for the sticky.

Well, I stayed put and he rolled 6-3, I hit and he danced. I won. It was close decision for me at the time. I guessed wrong and was handsomely rewarded for my ignorance. Go figure or "that's poker".

lol.