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Old 01-02-2014, 05:03 PM   #1
Fllecha
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How to play non-contact position bear-in

Hi guys

maybe this question is silly but In the last 10 games in which there was a race I made several errors (not blunders) according to XG in position similar to this one:

White - Pips 127

Black - Pips 130
Black to Play 4-3
Created with www.BGdiagram.com

because I don't know other general principles except:

"Don't waste pips in home board"
"Don't stack checkers"
"Try to balance during bear-in (i.e. try to cover empty points in your home board without wastage)
Don't be in hurry to break the midpoint

But playing on you reach this position and

White - Pips 109

Black - Pips 98
Black to Play 1-1
Created with www.BGdiagram.com

here for example 8/7(3) 6/5 is perfect move (even with home board wastage) but 8/7(2) 8/6 is an error (-0.064 according to XG)

Ok, maybe 8/6 pile too much checkers on 6 point, but how can it be an error?

In general what are the others missing principles that I forget?

Thanks
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Old 01-02-2014, 06:06 PM   #2
plm
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Re: How to play non-contact position bear-in

Quote:
Originally Posted by Fllecha View Post

because I don't know other general principles except:

"Don't waste pips in home board"
"Don't stack checkers"
"Try to balance during bear-in (i.e. try to cover empty points in your home board without wastage)
You don't really need to cover the lower points (and certainly not to make points there when there is no contact). Aim for a structure like 654000 (you'll probably have to dump some checkers deeper anyway).

In general, a combination of a gap on point N and a stack on point 2N is less harmful than it looks.

Quote:
Don't be in hurry to break the midpoint
If behind in the race, keep it since it has some real annoyance potential. If ahead, I would break it to protect from too many consecutive aces (although I suppose if you roll too many aces, you won't stay ahead in the race).

Quote:
here for example 8/7(3) 6/5 is perfect move (even with home board wastage) but 8/7(2) 8/6 is an error (-0.064 according to XG)
Are you sure both moves are evaluated at the same ply ? There are maybe 100 legal moves here, many of them relatively close in value ; XG will evaluate all of them at 1ply but only a few (that looked best at 1 ply) at the level you asked for analysis.

I don't see any other explanation for such a huge difference. These moves, and some more, should all be within 0.01 of equity

On the other hand, 8/7(3) 6/5, although reasonable, looks far from perfect. Putting 3 men on the 7 point is rather suspect. For me, 8/7 8/5 is the natural move.

Last edited by plm; 01-02-2014 at 06:07 PM. Reason: Typo
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Old 01-02-2014, 06:41 PM   #3
Fllecha
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Re: How to play non-contact position bear-in

Quote:
Originally Posted by plm View Post
You don't really need to cover the lower points (and certainly not to make points there when there is no contact). Aim for a structure like 654000 (you'll probably have to dump some checkers deeper anyway).
Now I got it. thanks.

Quote:
Originally Posted by plm View Post



If behind in the race, keep it since it has some real annoyance potential. If ahead, I would break it to protect from too many consecutive aces (although I suppose if you roll too many aces, you won't stay ahead in the race).
Can you explain what potential annoyances can make the midpoit in positions like the first one I posted? I read on a book, but I can't remember which one, and I don't know the reasons.

When I started BG in position like that I immediately cleared my midpoint and snowie (at that time I had that program) sometimes gave me some errors, that I couldn't understand. Can you post a clear case in which the midpoint can't be cleared?

Quote:
Originally Posted by plm View Post


Are you sure both moves are evaluated at the same ply ?
Mmm.. I think I didn't watch. I have to put the position up again. But I think that 0.06 isn't a misjudgement. I'll check it out
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Old 01-02-2014, 10:19 PM   #4
Taper_Mike
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Talking Re: How to play non-contact position bear-in

White - Pips 109

Black - Pips 98
Diagram 1. Black to Play 1-1

Something bad happened in between your first position and the second, which is diagrammed above. Somehow you ended up with a big stack on the 8pt. That will make it harder to get the distribution you want inside as you complete the bear in. Probably you rolled several 5s. If that is true, it may be that 10/5 or 8/3 would have been better than 13/8 for at least one or two of them.

For the 11 you have to play in Diagram 1, the table below lists all possible plays and their resulting EPCs. (EPC stands for effective pip count.) Note that the best of them, 8/7 8/5, unstacks the 8pt and puts checkers on points that need them. The second best, 8/6(2), unstacks the 8pt while making two crossovers. It puts too many checkers on the 6pt, but avoiding that turns out to be less important than having a diversified distribution outside. In fact, having as many as seven checkers on the 6pt may be ideal. See Diagram 2 below for an example.

Having checkers on the 7pt is problematic. It is useful in positions where the 6pt is light. That way you can efficiently play 7/6 when you roll an ace. In most positions, however, there is a danger that you will have to bear in too deeply when you crossover from the 7pt. In the table of Ideal Racing Positions linked below, there is only one position that has any checkers on the 7pt. These considerations explain why 8/6 8/7(2) turns out to be only 3rd-best in Diagram 1. That play puts too many checkers on both the 7pt and the 6pt.

EPC Table for Diagram 1

Code:
-----------------------------------------------------------------
 No.   Move                  EPC       Difference   % Difference
-----------------------------------------------------------------
  1.   8/7, 8/5              101.22    --           --
  2.   8/6(2)                101.277   0.0571141    0.0564259%
  3.   8/6, 8/7(2)           101.277   0.0577823    0.0570861%
  4.   10/9, 8/5             101.291   0.0711673    0.0703098%
  5.   10/9, 8/6, 8/7        101.293   0.0736177    0.0727307%
  6.   8/5, 6/5              101.303   0.0834381    0.0824328%
  7.   8/6, 8/7, 4/3         101.34    0.120745     0.11929%
  8.   8/5, 4/3              101.341   0.121497     0.120033%
  9.   8/4                   101.383   0.163573     0.161602%
 10.   10/9, 8/7(2), 6/5     101.387   0.167073     0.16506%
 11.   8/7(3), 6/5           101.409   0.189817     0.18753%
 12.   8/6, 8/7, 5/4         101.411   0.191777     0.189466%
 13.   8/7(2), 6/5(2)        101.415   0.195512     0.193156%
 14.   8/7(2), 6/5, 4/3      101.435   0.21505      0.212459%
 15.   10/9, 8/7, 6/5(2)     101.44    0.220601     0.217943%
 16.   8/7(2), 6/4           101.454   0.234264     0.231441%
 17.   10/9, 8/6, 4/3        101.474   0.254543     0.251476%
 18.   8/7, 6/4, 6/5         101.474   0.254704     0.251635%
 19.   10/9, 8/7(3)          101.478   0.258433     0.255319%
 20.   10/9, 8/7, 6/4        101.478   0.258618     0.255502%
 21.   10/9, 8/6, 5/4        101.491   0.271037     0.267771%
 22.   8/7, 6/3              101.493   0.273363     0.270069%
 23.   10/9, 8/7, 6/5, 4/3   101.495   0.275067     0.271753%
 24.   8/7, 6/5(2), 4/3      101.511   0.291852     0.288335%
 25.   8/6, 5/3              101.512   0.2921       0.28858%
 26.   8/6, 4/2              101.516   0.296162     0.292593%
 27.   10/6                  101.518   0.298128     0.294536%
 28.   8/7(3), 4/3           101.518   0.298881     0.29528%
 29.   10/9, 8/7(2), 4/3     101.526   0.306345     0.302653%
 30.   10/9, 8/7(2), 5/4     101.532   0.312467     0.308702%
 31.   10/7, 6/5             101.54    0.320299     0.31644%
 32.   8/7(4)                101.548   0.328809     0.324847%
 33.   8/7(2), 5/3           101.549   0.328953     0.324989%
 34.   8/7, 6/5, 4/2         101.553   0.333474     0.329456%
 35.   10/7, 8/7             101.554   0.334614     0.330583%
 36.   10/9, 6/4, 6/5        101.574   0.354886     0.35061%
 37.   8/7(3), 5/4           101.576   0.356007     0.351718%
 38.   8/7(2), 4/2           101.577   0.357217     0.352913%
 39.   6/3, 6/5              101.59    0.370191     0.36573%
 40.   10/9, 6/3             101.639   0.419859     0.4148%
 41.   10/9, 6/5(2), 4/3     101.642   0.422537     0.417445%
 42.   8/7, 6/5(3)           101.645   0.425366     0.420241%
 43.   10/9, 8/7, 5/3        101.651   0.431822     0.426619%
 44.   8/7, 4/1              101.68    0.460639     0.455089%
 45.   10/9, 8/7, 4/2        101.688   0.468116     0.462476%
 46.   8/6, 4/3(2)           101.688   0.468862     0.463213%
 47.   6/5, 4/1              101.692   0.472791     0.467095%
 48.   8/7, 6/5, 4/3(2)      101.715   0.49514      0.489174%
 49.   6/2                   101.716   0.496784     0.490798%
 50.   10/9, 6/5, 4/2        101.717   0.49729      0.491298%
 51.   6/4, 6/5(2)           101.719   0.499087     0.493074%
 52.   8/7, 5/2              101.721   0.501285     0.495245%
 53.   8/7, 6/4, 5/4         101.725   0.505407     0.499317%
 54.   8/7(2), 4/3(2)        101.729   0.50911      0.502976%
 55.   6/5(2), 4/2           101.735   0.515344     0.509135%
 56.   10/9, 6/5(3)          101.736   0.51614      0.509921%
 57.   10/8, 6/5(2)          101.736   0.516284     0.510064%
 58.   6/4(2)                101.749   0.529354     0.522976%
 59.   8/7, 5/3, 4/3         101.769   0.549149     0.542532%
 60.   6/3, 5/4              101.77    0.550554     0.54392%
 61.   6/3, 4/3              101.772   0.552209     0.545555%
 62.   10/7, 4/3             101.772   0.552756     0.546096%
 63.   10/7, 5/4             101.774   0.554422     0.547742%
 64.   10/8, 6/4             101.776   0.555943     0.549244%
 65.   8/7, 4/2, 4/3         101.798   0.578531     0.571561%
 66.   10/9, 6/4, 5/4        101.798   0.578697     0.571725%
 67.   8/7(2), 5/4(2)        101.803   0.582936     0.575912%
 68.   8/7, 5/3, 5/4         101.806   0.586142     0.57908%
 69.   10/8, 6/5, 4/3        101.808   0.587931     0.580847%
 70.   10/9, 4/1             101.812   0.591989     0.584856%
 71.   10/9, 8/7, 5/4(2)     101.825   0.605079     0.597789%
 72.   6/5, 4/2, 4/3         101.829   0.609708     0.602361%
 73.   10/9, 8/7, 4/3(2)     101.832   0.612167     0.604791%
 74.   10/9, 6/5, 4/3(2)     101.863   0.64324      0.635489%
 75.   6/5(3), 4/3           101.874   0.654518     0.646631%
 76.   8/6, 5/4(2)           101.882   0.662171     0.654193%
 77.   10/9, 5/2             101.892   0.672392     0.66429%
 78.   6/5(2), 4/3(2)        101.901   0.681879     0.673663%
 79.   5/1                   101.916   0.696772     0.688376%
 80.   4/1, 4/3              101.956   0.736688     0.727812%
 81.   5/2, 4/3              101.957   0.737437     0.728551%
 82.   10/9, 5/3, 4/3        102.018   0.798483     0.788862%
 83.   10/9, 5/3, 5/4        102.027   0.807392     0.797663%
 84.   10/8, 5/3             102.03    0.810691     0.800923%
 85.   10/9, 4/2, 4/3        102.063   0.843517     0.833353%
 86.   5/3(2)                102.092   0.872499     0.861986%
 87.   10/8, 4/2             102.099   0.87903      0.868439%
 88.   4/2(2)                102.205   0.985561     0.973686%
 89.   5/2, 5/4              102.213   0.993842     0.981867%
 90.   6/5(4)                102.221   1.00176      0.989687%
 91.   6/4, 5/4(2)           102.355   1.13552      1.12184%
 92.   10/8, 4/3(2)          102.383   1.16381      1.14979%
 93.   5/3, 4/3(2)           102.396   1.17621      1.16204%
 94.   10/8, 5/4(2)          102.44    1.22001      1.20531%
-----------------------------------------------------------------
White - Pips 0

Black - Pips 79
Diagram 2. ideal Bear-in Position in a Non-contact Race

In many racing positions, the ideal checker arrangement minimizes EPC. To that end, it is worth knowing a couple of reference positions. The one above, with a 7-5-3 distribution, is the one you should have been aiming for when you began the bear in. See Ideal Racing Positions for a list of other ideal positions.

In practice, you won't always be able to reach an ideal position. Here are some of the things to keep in mind: Making crossovers is important, but is not always the top priority. Stay diversified outside. Work to reach a wedge shape, such as the ones shown in Diagrams 2 and 3. A smaller, but similarly shaped wedge is often best for the checkers that remain outside. Diagrams 2, 3, and 4, all of which show wedges, are ideal at their respective pip counts when all 15 checkers are still in play on or below the 11pt.

As the number of checkers outside diminishes, the wedge is no longer best. Shapes with a hump towards the rear are better. Diagrams 5 and 6 are examples of this. Beginning from either one, Black has a good chance to reach the 7-5-3 distribution of Diagram 2.


Black - Pips 70
Diagram 3. Woolsey's Wedge


Black - Pips 130
Diagram 4. Woolsey's Wedge in the outfield


Black - Pips 113
Diagram 5. Later on, a humped shape replaces the wedge outside.


Black - Pips 103
Diagram 6. Still later, a small hump remains.

Mike
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Old 01-02-2014, 10:28 PM   #5
Robertie
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Re: How to play non-contact position bear-in

I agree that there should be a bunch of plays here within 0.01 of each other. I'd put it through XG again and see what happens.

When bearing in, you want to aim for a target position, which will represent the ideal bearoff stucture for a given pip count and 15 checkers. I use two target positions for guideposts:

Position 1 (15 checkers, 79 pips): 3 on 4-point, 5 on 5-point, 7 on 6-point.

Position 2 (15 checkers, 70 pips): 1 on 2-point, 2 on 3-point, 3 on 4-point, 4 on 5-point, 5 on 6-point.

Position 2 is particularly easy to remember because of the triangle structure.

In the original position, I'd play 8/5 8/7, which could lead to either Position 1 or 2 depending on the rolls.
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Old 01-02-2014, 10:31 PM   #6
Robertie
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Re: How to play non-contact position bear-in

BTW, the original position was a big double. There's no point in gaining 0.01 points of equity by playing 1-1 correctly and lose a bunch by forgetting to double.
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Old 01-03-2014, 11:01 AM   #7
Fllecha
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Re: How to play non-contact position bear-in

Quote:
Originally Posted by Robertie View Post
BTW, the original position was a big double. There's no point in gaining 0.01 points of equity by playing 1-1 correctly and lose a bunch by forgetting to double.
the cube was on opponent side, I simply misplaced it.

First of all I thank you all for the complete answers. It's really nice to study this game and this material. Now I can have a better understanding of this part of the game that for me was always obscure.
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Old 02-08-2019, 08:57 AM   #8
hagadol
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Re: How to play non-contact position bear-in

Bill

How are you deciding on which of the two structures to aim for ? I am assuming
this is based on the the existing checkers in the home board and
what the dice actually offer you in the process.

Are there techniques to achieve these ideal positions in the way that you choose
which checkers to move from your outer board / mid point ?

Thanks

Hagadol


Quote:
Originally Posted by Robertie View Post
I agree that there should be a bunch of plays here within 0.01 of each other. I'd put it through XG again and see what happens.

When bearing in, you want to aim for a target position, which will represent the ideal bearoff stucture for a given pip count and 15 checkers. I use two target positions for guideposts:

Position 1 (15 checkers, 79 pips): 3 on 4-point, 5 on 5-point, 7 on 6-point.

Position 2 (15 checkers, 70 pips): 1 on 2-point, 2 on 3-point, 3 on 4-point, 4 on 5-point, 5 on 6-point.

Position 2 is particularly easy to remember because of the triangle structure.

In the original position, I'd play 8/5 8/7, which could lead to either Position 1 or 2 depending on the rolls.
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Old 02-08-2019, 10:53 AM   #9
Robertie
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Re: How to play non-contact position bear-in

Good question. In practice Woolsey's Wedge (5-4-3-2-1) is much much more common than Trice's Tower (7-5-3). I suppose this is because a lot of races result after some effort has been made to build the home boards, after which one side throws a big double and we're in a race. I know I've built the wedge innumerable times, but I'm not sure I've ever actually built the tower.
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Old 02-08-2019, 08:47 PM   #10
hagadol
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Re: How to play non-contact position bear-in

Bill

Are there any special techniques, when bearing in, to aim for these positions ?

Regards

Hagadol
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Old 02-08-2019, 11:21 PM   #11
Robertie
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Re: How to play non-contact position bear-in

No special techniques, just look at the roll and position and make a judgement as to which play brings you closest to the position you want.
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