Open your mind - Page 5 - Backgammon Forum - Discuss Backgammon Strategy, Clubs and Books

Thanks, Yogiman.

I overestimated the danger of being hit twice. In the OP, White has only 9 in the zone, so Black can often survive a double hit. From the bar, he will be shooting at two blots. When he hits one of them, White falls to only 8 in the zone, with a checker on the bar.

I am a little surprised that bringing a 10th checker into the zone, as in your second diagram, does not push bar/24 to the top. I guess, Black is losing so often after bar/24 that he may as well try for the 20pt. If he is successful in making it, his equity will jump.

Mike

Quote

04-05-2015 , 05:21 PM

#102

Fllecha

journeyman

Join Date: Mar 2010 Posts: 321

I thank you too.. Its an interesting position btw, but sincerely i dont Belive the bots this time Lol.

Quote

04-07-2015 , 04:51 AM

#103

Taper_Mike

adept

Join Date: Sep 2009 Posts: 1,030

White - Pips 90

Black - Pips 74
Position 13. Black to Play 5-2

Unlimited game, no Jacoby, no beavers
XGID=-BCDaBB-A-a--------ccbcbA-:1:1:1:52:0:0:0:0:10

The usual stuff: what and why?

Mike

Quote

04-07-2015 , 05:35 AM

#104

Kamba

enthusiast

Join Date: Feb 2015 Posts: 93

Firstly I would panic.

After re-grouping I would play 6/1 6/4*

I'm guessing 8/6/1 guarantees me a loss, but it might save me a gammon. It just seems too passive and does not appeal.

6/1 6/4* gives me some chance of escaping, but i suppose increases my chances of being gammoned somewhat. But thats the move I would make.

Quote

04-07-2015 , 05:38 AM

#105

Fllecha

journeyman

Join Date: Mar 2010 Posts: 321

One may Be tempted to click the panic button with 6/4* 6/1 trying to cover next turn and maybe escape or build a 5 board but the draw back is a likely gammon. Here i think that black goal is simply to fold john wayne hat to avoid being gammoned and i play 8/1 final answer.

After avoiding the 6-shot that nail me down i put on my Nike shoes for some 6 to escape and win the race

Last edited by Fllecha; 04-07-2015 at 05:58 AM.

Quote

04-07-2015 , 08:16 AM

#106

yogiman

adept

Join Date: Jun 2012 Posts: 784

I rather don't admit it, but I do agree with Fllecha. 6/4 6/1* is a typical DMP move.

Quote

04-07-2015 , 02:27 PM

#107

Alpha Fish

Pooh-Bah

Join Date: Aug 2008 Posts: 3,831

most likely sequence after passive escape is white hits loose and then either closes us out (often with 2 on the bar) or we hit back and half of our returns crunch home board anyway

so we're not losing THAT many more gammons, fire away

Quote

04-07-2015 , 04:23 PM

#108

Fllecha

journeyman

Join Date: Mar 2010 Posts: 321

Quote:

Originally Posted by Alpha Fish

so we're not losing THAT many more gammons, fire away

You are free to not Belive me of course and i usually hate bot moves but you may perform a rollout and you Will surely found a SIGNIFICANT difference on gammons i judged only on my experience.

I Belive that on about 30% of the cases you Will lose a gammon more or less. Ok that Number is just a rough extimation, but it gives an idea.

At dmp i Will surenly hit like a boss!

Quote

04-09-2015 , 06:50 AM

#109

Taper_Mike

adept

Join Date: Sep 2009 Posts: 1,030

White - Pips 90

Black - Pips 74
Position 13. Black to Play 5-2

This position arose during head-to-head play with a player in my weekly chouette group.

I was not a happy camper when I rolled this 52. Evincing mild disgust, I picked up a checker from the 6pt and put it on top of my opponent’s checker on the 4pt. That got a good laugh out of my friend. Then I fiddled around a bit, and finally moved the remaining blot down to the 1pt. I did that just so I could see what killing another checker looked like. For the effort, my friend taunted me with, “What are you, chicken?”

“You got that right!” is all I could say.

After some consideration, I finally reset the position, and muttering something about gammons, I played 8/1.

When I checked with a bot later, and found that my play had been correct, I decided to post the position here. It is the perfect anti-QF position. The best play is not the fancy QF-hit. It’s the simple safe play. At DMP, where gammons do not count, hitting is correct. Rollout are below.

Hitting nets 8% more wins, but loses an additional 20% gammons. It also loses an extra 1.5% backgammons.

Mike

5k XG2 Rollout – Unlimited game, no Jacoby, no beavers

Code:

XGID=-BCDaBB-A-a--------ccbcbA-:1:1:1:52:0:0:0:0:10

X:Player 1   O:Player 2
Score is X:0 O:0. Unlimited Game
Pip count  X: 74  O: 90 X-O: 0-0
Cube: 2, X own cube
X to play 52

    1. Rollout¹    8/1               eq:-0.6975
      Player:   14.72% (G:2.29% B:0.02%)
      Opponent: 85.28% (G:5.04% B:0.13%)
      Confidence: ±0.0022 (-0.6996..-0.6953) - [100.0%]

    2. Rollout¹    6/1 6/4*          eq:-0.7199 (-0.0225)
      Player:   22.93% (G:2.26% B:0.02%)
      Opponent: 77.07% (G:25.26% B:1.53%)
      Confidence: ±0.0021 (-0.7220..-0.7179) - [0.0%]

¹  5184 Games rolled with Variance Reduction.
   Dice Seed: 45538570
   Moves: 3-ply, cube decisions: XG Roller

Rollout by Taper_Mike
2015-Apr-07
eXtreme Gammon Version: 2.10.199.2658
OpenYourMind.013.xgp

5k XG2 Rollout – Double Match Point

Code:

XGID=-BCDaBB-A-a--------ccbcbA-:0:0:1:52:0:0:0:1:10

X:Player 1   O:Player 2
Score is X:0 O:0 1 pt.(s) match.
Pip count  X: 74  O: 90 X-O: 0-0/1
Cube: 1
X to play 52

    1. Rollout¹    6/1 6/4*          eq:-0.5452
      Player:   22.74% (G:2.16% B:0.01%)
      Opponent: 77.26% (G:20.28% B:1.08%)
      Confidence: ±0.0011 (-0.5463..-0.5440) - [100.0%]

    2. Rollout¹    8/3 6/4*          eq:-0.6512 (-0.1060)
      Player:   17.44% (G:1.61% B:0.01%)
      Opponent: 82.56% (G:23.67% B:1.14%)
      Confidence: ±0.0011 (-0.6523..-0.6501) - [0.0%]

    3. Rollout¹    8/1               eq:-0.7072 (-0.1621)
      Player:   14.64% (G:2.68% B:0.01%)
      Opponent: 85.36% (G:3.67% B:0.06%)
      Confidence: ±0.0010 (-0.7083..-0.7062) - [0.0%]

¹  5184 Games rolled with Variance Reduction.
   Dice Seed: 45538570
   Moves: 3-ply, cube decisions: XG Roller

Rollout by Taper_Mike
2015-Apr-07
eXtreme Gammon Version: 2.10.199.2658
MET: Kazaross XG2
OpenYourMind.013-d.xgp

Quote

04-10-2015 , 10:04 AM

#110

yogiman

adept

Join Date: Jun 2012 Posts: 784

Position ID: xoZxwBE022CADQ Match ID: cAkXAAAAAAAE

White - Pips 168

Black - Pips 165
Black to Play 6-5
Created with www.BGdiagram.com

Quote

04-10-2015 , 11:48 AM

#111

Karol Szczerek

enthusiast

Join Date: Mar 2015 Posts: 92

For me it's the obvious 22/16 21/16.

With such many checkers back for us and for opponent, the control of the outfield is the key. He doesn't have enough ammunition to carry an attack, and if he tries, he most likely will fail or be counter-attacked, and he would need to surrender his outfield point. I think with most rolls he even shouldn't hit, but rather play into the outfield too.

This play gives us connectivity, maintains flexibility, start to extradicate our back men, keeps all game plans open.

We shouldn't hit with 8/2* 8/3, because attacking is the last plan here. All we will gain by this play is loosing a blocking point, flexibility, connectivity.

Third and worst play would be probably 13/8 13/7 as it looses our connectivity even more that the hit. After this, it will be miracle to run our 4 men back through the jungle of opponent's outfield to safety.

Quote

04-10-2015 , 01:29 PM

#112

yogiman

adept

Join Date: Jun 2012 Posts: 784

Code:

1. 22/16 21/16                  Eq.:  -0,067
       0,504 0,119 0,005 - 0,496 0,173 0,008 CL  -0,048 CF  -0,067
     
2. 8/3 8/2*                     Eq.:  -0,178 ( -0,112)
       0,460 0,129 0,004 - 0,540 0,165 0,006 CL  -0,118 CF  -0,178
    
3. 22/11                        Eq.:  -0,213 ( -0,146)
       0,462 0,106 0,004 - 0,538 0,173 0,007 CL  -0,146 CF  -0,213

Quote

04-10-2015 , 01:49 PM

#113

yogiman

adept

Join Date: Jun 2012 Posts: 784

Position ID: m7sDBgC2bQA4DA Match ID: UykGAAAAAAAE

White - Pips 77

Black - Pips 138
Black to Play 5-1
Created with www.BGdiagram.com

Quote

04-10-2015 , 03:18 PM

#114

Karol Szczerek

enthusiast

Join Date: Mar 2015 Posts: 92

These are tough positions, as tiniest differencies matter and determine which plan is good and the other plans are usually blunders. Also because of many gammons roaming around. I don't have a good ready-to-go way to calculate these.

After many blunders in such high/deep anchor holding games I've learned that it's often correct to abandon the deep anchor unless it's really risky or You have a good other play. The problem here is that there are no alternatives to the running 22/17 18/17 play. Any other move crunch our homeboard.

18/13 would be good if we had a 1 to play on the other side of the board (i.e. 4-pt. board with spares, so we could move 1 spare with a 1) and I'd play it in a heartbeat then. Here we would have to go 18/13 6/5, which gives up too much of our counter-play, as it opens up the homeboard.

6/1 2/1 or 6/1 6/5 is non-sense. We hold the ground, but destroy our potential for counter-play. It's almost always better to keep the board and take even ridiculous risks on the other side of the board. Even if we had any spare in our homezone it would be better to go 18/13 + ace with the spare then shuffle homeboard points.

To sum up, I'd close my eyes and go with 22/17 18/17. It looks scary, but there's no alternative. The blot isn't in that much of a danger - there are only few pointing or hit-n-pass numbers for opponent. And any other is OK for us. If he hits loose we have direct shot at winning. If he plays safe inside the board, we can run the blot to the anchors or further to 13-16 points. OR with doubles we will move either anchor, as the blot won't be in much danger. I dismiss 18/13 only because there's no neutral ace to play.

Quote

04-10-2015 , 05:24 PM

#115

Taper_Mike

adept

Join Date: Sep 2009 Posts: 1,030

Down by 60-some pips, Black must hit to win. Afterwards, he must contain the checker he hits. Because White may be leaving shots immediately, Black does not want to bust his board with 6/1 6/5 or 6/1 2/1. Those might be reasonable plays if Black had builders available to remake the 6pt quickly and there were few or no rolls that forced White to leave a shot on this turn.

Splitting the 18pt is certainly not an option either. 18/13 would be fine, but then there is no ace.

Almost by default, making the 17pt is the play. There are no decent alternatives. Afterwards, 8 rolls have White closing his board. Another pair let White switch points, from the 6pt or 5pt down to the 3pt. There are actually no pick-and-pass rolls, but only because the ones that do that are better played closing the board.

Karol gives a nice analysis above.

Mike

Quote

04-11-2015 , 12:13 AM

#116

uberkuber

veteran

Join Date: Jul 2009 Posts: 3,032

Wouldn't 2-2 be a pick and pass roll for White? I'd rather do this than switching points.

Edit: Unless White wants to play it 13/9 (2)?

Quote

04-11-2015 , 04:24 AM

#117

Taper_Mike

adept

Join Date: Sep 2009 Posts: 1,030

Quote:

Originally Posted by uberkuber

Wouldn't 2-2 be a pick and pass roll for White? I'd rather do this than switching points.

Edit: Unless White wants to play it 13/9(2)?

You are right twice!

1. I was thinking of 22 as a switching roll, and 2. It is better played moving two checkers to the 9pt.

Mike

Quote

04-11-2015 , 04:46 AM

#118

yogiman

adept

Join Date: Jun 2012 Posts: 784

White in direct range of his homeboard and black on the bar is looking fine.

Quote

04-11-2015 , 07:53 AM

#119

uberkuber

veteran

Join Date: Jul 2009 Posts: 3,032

So you prefer 5/3*/1 13/11(2) to 13/9(2)?

Quote

04-11-2015 , 09:41 AM

#120

yogiman

adept

Join Date: Jun 2012 Posts: 784

You start stressing me, man.

Code:

    1. Cubeful 2-ply    13/9(2)             Eq.:  +1,224
       0,905 0,354 0,001 - 0,095 0,006 0,000
        2-ply cubeful prune [world class]
    2. Cubeful 2-ply    13/11(2) 5/3*/1 Eq.:  +1,147 ( -0,077)
       0,764 0,484 0,003 - 0,236 0,025 0,000
        2-ply cubeful prune [world class]

Quote

04-12-2015 , 02:38 AM

#121

yogiman

adept

Join Date: Jun 2012 Posts: 784

Code:

   1. 22/17 18/17                  Eq.:  -0,468
       0,374 0,067 0,004 - 0,626 0,412 0,001 CL  -0,595 CF  -0,468
      
    2. 18/13 6/5                    Eq.:  -0,538 ( -0,070)
       0,313 0,024 0,001 - 0,687 0,298 0,007 CL  -0,655 CF  -0,538
      
    3. 6/5 6/1                      Eq.:  -0,561 ( -0,092)
       0,287 0,017 0,000 - 0,713 0,245 0,005 CL  -0,658 CF  -0,561

This position belongs to the category of high volatility decisions, which are so hard to evaluate for us. There are three builders for making the 22w-point, which makes 7/36. 33 and 22 put black on the bar with an open board-point. So with a quick look almost 25% leads to a sure gammon for white. That's a big prize, and without prior knowledge I would opt for one of the other two moves, and that's no shame, nor a disaster. In any way, you have seen it now.

However, this position was not the one that I encountered during my play, which I adapted because I felt that it would not excite the experts (btw, thanks for your great contribution):

White - Pips 76

Black - Pips 138

Code:

    1. 22/17 18/17                  Eq.:  -0,188
       0,440 0,063 0,002 - 0,560 0,282 0,001 CL  -0,337 CF  -0,188
     
    2. 18/13 2/1                    Eq.:  -0,461 ( -0,273)
       0,345 0,031 0,001 - 0,655 0,307 0,005 CL  -0,591 CF  -0,461
      
    3. 6/1 2/1                      Eq.:  -0,509 ( -0,320)
       0,309 0,021 0,000 - 0,691 0,254 0,004 CL  -0,618 CF  -0,509

Quote

04-13-2015 , 02:45 AM

#122

yogiman

adept

Join Date: Jun 2012 Posts: 784

Position ID: O+6AwQAzO4MBBg Match ID: cAkSAAAAAAAE

White - Pips 103

Black - Pips 120
Black to Play 4-4
Created with www.BGdiagram.com

Quote

04-13-2015 , 03:56 AM

#123

bleep69

grinder

Join Date: Sep 2008 Posts: 483

After a long break, I'm eager to leap back into getting these wrong.

We will still be behind after the roll, but only by 1, so nothing too serious there. I've noticed that behind is behind though, regardless of magnitude, and so we will still want contact. I'd play 21/17 (2) 8/4 (2). White has a poor trap that only very few rolls immediately help with, and there's a good chance he will leave something exposed shortly, unless he really wants to ruin his home board. Given another 30 seconds thought, I can completely convince myself that any other use of 44 is much better than my original choice, so I am stopping here.

Quote

04-13-2015 , 11:47 AM

#124

Fllecha

journeyman

Join Date: Mar 2010 Posts: 321

Edit misread position

Last edited by Fllecha; 04-13-2015 at 11:55 AM.

Quote

04-13-2015 , 12:01 PM

#125

Karol Szczerek

enthusiast

Join Date: Mar 2015 Posts: 92

My first thought would be 21/17(2) 13/9(2). It keeps guns at both opponent's outfield points and gives me good timing by allowing to play from 7 or 8 pt. into homeboard.

21/17(2) 8/4(2) keeps pressure too, but keeps almost no flexibility. On the other hand our threat is bigger due to better homeboard. These 2 factors probably sort of even out, so it's probably close.

Whenever I've encountered similar positions I've learned that keeping the back-most anchor is valued strongly by bot too. It's often good enough to surrender some flexibility elsewhere. I guess it's because some doublets won't let the opp pass us.

I see 2 plays that keep the back guard:
8/4(2) 6/2(2) - gives good board, but again, no flexibility
21/13 8/4(2) - the blot isn't in much danger, and 8/4(2) is automatic to guard it indirectly by making opp's attack more dangerously for him.
There is also 13/9(2) 8/4(2) but it opens too much outfield and gives opp flexibility, so no-no for me.

I like 2 plays: 21/17(2) 13/9(2) and 21/13 8/2(2) and I'd probably coin-toss between these too.

I shoot for my initial feeling and go with the 21/17(2) 13/9(2).

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