Open your mind - Page 14 - Backgammon Forum - Discuss Backgammon Strategy, Clubs and Books

I like keeping the middle point and run one guy from the back in most of this type of positions. Here, with opp having not much ammunition and being stripped everywhere, I'm pretty sure, that 21/12 is correct, too. It keeps pressure everywhere.

Quote

07-21-2015 , 07:26 PM

#328

Zengammon

stranger

Join Date: Jul 2015 Posts: 3

I'm not running from the 21. I want to shoot him for a few rolls, not one, if I'm missed on the next roll. His 4s are bad right now. And I don't want to give him a chance to simplify the game by hitting on the 21. Yes, the 19 is open, but it is higher and better for him if I enter there. And the 16 fans when hit on the 21 may draw a cube. So, 13/10, 13/7. The blot on the 10 still squeezes him when not hit and leaves the least number of shots.

Quote

07-21-2015 , 07:35 PM

#329

Zengammon

stranger

Join Date: Jul 2015 Posts: 3

And, if White rolls a non 1, non joker on the next roll, he will start blotting or wreck his board. If the board goes, i can then split freely from the 21 if i want.

Quote

07-23-2015 , 09:59 AM

#330

yogiman

adept

Join Date: Jun 2012 Posts: 784

Code:

21/12                        Eq.:  -0,243
       0,438 0,120 0,008 - 0,562 0,143 0,001 CL  -0,141 CF  -0,243
    
13/7 4/1                     Eq.:  -0,365 ( -0,123)
       0,409 0,082 0,002 - 0,591 0,097 0,002 CL  -0,196 CF  -0,365
     
13/4                         Eq.:  -0,366 ( -0,123)
       0,397 0,076 0,002 - 0,603 0,077 0,001 CL  -0,205 CF  -0,366
 
13/10 13/7                   Eq.:  -0,425 ( -0,182)
       0,394 0,068 0,003 - 0,606 0,071 0,001 CL  -0,212 CF  -0,425
      
13/7 5/2                     Eq.:  -0,486 ( -0,244)
       0,361 0,063 0,001 - 0,639 0,095 0,001 CL  -0,308 CF  -0,486

Without reference position it is not easy to see what is the right move here. The cubeless difference is only 0.55, so it again has to do with the cube efficiency, but more about that in the next position.

If after 13/4 there is a good spread of builders, there is even no cubeless difference. Moving 4 to 6:

Code:

21/12                        Eq.:  -0,217
       0,439 0,124 0,007 - 0,561 0,142 0,001 CL  -0,135 CF  -0,217
  
13/4                         Eq.:  -0,287 ( -0,070)
       0,421 0,088 0,003 - 0,579 0,077 0,001 CL  -0,146 CF  -0,287

Quote:

Originally Posted by Karol Szczerek

Here, with opp having not much ammunition and being stripped everywhere, I'm pretty sure, that 21/12 is correct

Giving white some flexibility by moving 23w to 17:

Code:

21/12                        Eq.:  -0,390
       0,393 0,103 0,004 - 0,607 0,148 0,001 CL  -0,257 CF  -0,390
    
13/10 13/7                   Eq.:  -0,440 ( -0,050)
       0,393 0,069 0,002 - 0,607 0,062 0,001 CL  -0,208 CF  -0,440

13/4                         Eq.:  -0,481 ( -0,092)
       0,371 0,058 0,001 - 0,629 0,064 0,001 CL  -0,263 CF  -0,481

They are getting close now. 61,51,52 can be played safe now. But most importantly, white can hit without breaking his 17-point.
Observe that this is a case, in which the cubeless equity of the first move is less, than that of the second move. The reason is presumably, that if white hits on the 21-point, and black doesn't enter, in both board positions it will be a pass. However, with an extra checker on the 17-point white would have won more when the game would have been played to the end. So the cube is not efficient in this case for white.

With a 5-board the cubeless difference is 0,08, which makes it more suitable to draw a conclusion:

Code:

21/12                        Eq.:  -0,017
       0,484 0,142 0,007 - 0,516 0,107 0,000 CL  +0,010 CF  -0,017

13/4                         Eq.:  -0,208 ( -0,190)
       0,444 0,092 0,003 - 0,556 0,059 0,000 CL  -0,077 CF  -0,208

13/10 13/7                   Eq.:  -0,287 ( -0,270)
       0,432 0,084 0,003 - 0,568 0,046 0,000 CL  -0,096 CF  -0,287

Quote:

Originally Posted by uberkuber

I want to keep a lot of contact, so I hesitate between 13/7 5/2 and 13/7 13/10.

If white hits, there is no contact anymore. After 13/7 13/10 black can skip the two checkers, leaving only indirect shots.

Quote:

Originally Posted by Bleep

Getting hit is not the end of the world for black, I think the trick here lies with offering a target that gives us a return shot. The best move I can see for this is 21/12

There is something to say for this. The average chance for a return shot after a white 3 is about 15%. Moreover, white's 51,52,65 and 41,42,44,54 will be played from the 17w-point, leaving white's 9w-point intact, though in the latter case black will be on the bar.

Quote:

Originally Posted by zengammon

His 4s are bad right now. And I don't want to give him a chance to simplify the game by hitting on the 21.

Only 44,66 are really bad. With the other 4's he is favorite to enter.

Quote:

Originally Posted by zengammon

So, 13/10, 13/7. The blot on the 10 still squeezes him when not hit and leaves the least number of shots.

Only in the case of 62,63,65. And 64 will leave a direct shot, but it would also do after 21/12.

Also with a seemingly better 4-board for white, 21/12 is by far the best move. 24 to 19-point:

Code:

21/12                        Eq.:  -0,429
       0,386 0,098 0,006 - 0,614 0,153 0,003 CL  -0,281 CF  -0,429
   
13/10 13/7                   Eq.:  -0,575 ( -0,146)
       0,345 0,048 0,002 - 0,655 0,069 0,003 CL  -0,332 CF  -0,575

Conclusion:
21/12 is the best move, because both players have stripped points, and black will retain maximum contact also after the next move. This makes up for a possible mishap caused by the loss of the defensive point.

Quote

07-23-2015 , 08:50 PM

#331

Zengammon

stranger

Join Date: Jul 2015 Posts: 3

yogiman, thanks for your feedback and contributions here. Very helpful to a very rusty guy who walked away from the game in 1990 and just last week decided to explore a return. This and 'extreme gammon'...which I just bought--Amazing. The bg world has really changed.

Quote

07-24-2015 , 03:17 AM

#332

yogiman

adept

Join Date: Jun 2012 Posts: 784

You thanks either. Nice to hear that the game of backgammon makes you so happy, and that my thread contributes a little to it makes me happy too. This is what you call a win-win situation.

Quote

07-24-2015 , 11:06 AM

#333

yogiman

adept

Join Date: Jun 2012 Posts: 784

Position ID: bM4AIG7Eb4cCEA
Match ID: cIkOAAAAAAAE

White - Pips 191

Black - Pips 125
Black to Play 5-3
Created with www.BGdiagram.com

Quote

07-24-2015 , 11:48 AM

#334

Karol Szczerek

enthusiast

Join Date: Mar 2015 Posts: 92

6/3 is automatic with 6 guys on the 6pt. After that the 23/18 should be better than 12/7. Opp has stronger board and dangerous structure in front of our back checker. A loose hit with few our blots lying around could turn the game around.

An onslaught with 8/3 7/4* is a bad idea. With so many opp's checkers back we have many gammons anyway (probably like 1/2 of our wins), so why risk a hit-dance sequence or expose ourselves too much for a joker doublet.

Bill Robertie wrote a very valuable and precise piece of advice a couple posts ago, or maybe in another topic (sorry if I got the wording wrong):
In hopeless position play to give yourself best chances if opp rolls badly, as if he rolls good You are lost no matter what You do.

The conclusion is that as a winning side You should do the opposite - cut down on opp's joker rolls that gets him out of the grave.
23/18 6/3 does exactly that.

Quote

07-24-2015 , 05:29 PM

#335

_Z_

adept

Join Date: Jul 2004 Posts: 720

Cube's in the middle? I guess it's too good before the roll? If White's home board was a little weaker, trying to blow him off the board with 7/4* 8/3 might be right, but as it stands, it looks like it gives him too much on his 4s. Here I would just try the solid 6/3, and then play the 5 that seems to do the most good. 23/18 6/3

Quote

07-24-2015 , 05:58 PM

#336

uberkuber

veteran

Join Date: Jul 2009 Posts: 3,032

The 3 seems automatic (6/3).

As for the 5, I hesitate between moving the straggler (23/18) or bringing ammo with 12/7.

Also, why didn't Black double before this roll? Unless he's now too good and Jacoby is turned off?

If gammons are activated, 8/3 7/4* now seems appealing too though.

Screw it, if gammons count, I go with 8/3 7/4*.
Otherwise, 12/7 6/3.

Quote

07-24-2015 , 06:00 PM

#337

uberkuber

veteran

Join Date: Jul 2009 Posts: 3,032

Damn, should have read other comments before posting...

Quote

07-25-2015 , 05:47 AM

#338

bleep69

grinder

Join Date: Sep 2008 Posts: 483

I did read the comments before posting unfortunately. However, I'd have played 12/7, bringing in more ammunition to hopefully close white out while he has 2 guys on the bar.

Having read Karol's explanation, I can see the logic.

Quote

07-26-2015 , 10:58 AM

#339

yogiman

adept

Join Date: Jun 2012 Posts: 784

Code:

23/18 6/3                    Eq.:  +0,996
       0,683 0,376 0,065 - 0,317 0,047 0,002 CL  +0,758 CF  +0,996
   
12/7 6/3                     Eq.:  +0,958 ( -0,038)
       0,670 0,376 0,066 - 0,330 0,050 0,001 CL  +0,731 CF  +0,958
   
8/3 7/4*                     Eq.:  +0,829 ( -0,168)
       0,651 0,396 0,084 - 0,349 0,084 0,007 CL  +0,692 CF  +0,829

This is meant to be an obvious=obvious problem, though you are free to disagree.
Because this is a backgame position I have done 1296 trials, like with most positions in this post. There is barely any difference between 23/18 and 12/7, but as a general rule (e.g. 44,66) it is wise to play from the back (see Modern Backgammon, Robertie). The cubeless difference between playing safe and hitting loose is relatively small, so it is not so easy to judge by the naked eye.

Ofcourse it gets worse with a better 3-board. 22w to 20:

Code:

23/18 6/3                    Eq.:  +0,893 
       0,645 0,362 0,065 - 0,355 0,054 0,002 CL  +0,660 CF  +0,893 

8/3 7/4*                     Eq.:  +0,676 ( -0,217) 
       0,597 0,364 0,082 - 0,403 0,098 0,008 CL  +0,535 CF  +0,676

Here the cubeless difference is 0.12, which supports and facilitates an analysis of the former position.

-------

Position after 23/18 6/3:

As a matter of fact, if black plays safe and white subsequently throws a 4, he is pretty much out of the grave:

White has played 64:

Code:

Cube analysis
Rollout cubeless equity  +0,539

Cubeful equities:
1. Double, take         +0,820
2. Double, pass         +1,000  ( +0,180)
3. No double            +0,794  ( -0,026)
Proper cube action: Double, take

White has played 54:

Code:

Cube analysis
Rollout cubeless equity  +0,480

Cubeful equities:
1. Double, take         +0,695
2. Double, pass         +1,000  ( +0,305)
3. No double            +0,693  ( -0,002)
Proper cube action: Double, take

The position was initially too good to double, but black has barely a double in these cases.

Whereas, if white doesn't throw a 4, the position will still be too good to double:
White has played 51:

Code:

Cube analysis
Rollout cubeless equity  +0,790

Cubeful equities:
1. Double, pass         +1,000
2. Double, take         +1,376  ( +0,376)
3. No double            +0,991  ( -0,009)
Proper cube action: Double, pass

--------

This brings up the question how bad it is if, after 7/4*, black's blot is hit. White has played 41 after black's 8/3 7/4*, and black is on the bar:

Code:

Cube analysis
Rollout cubeless equity  +0,266

Cubeful equities:
1. No double            +0,333
2. Double, pass         +1,000  ( +0,667)
3. Double, take         +0,195  ( -0,138)
Proper cube action: No double, take

Well, very bad. Black had an equity of almost 1,0 in the original position, and this had dropped to 0,27. White, having the better board, gets a chance to start a whole new game from the back.

---------

By the way, black's many blots are of no concern. 13 to 12:

Code:

23/18 6/3                    Eq.:  +1,004 
       0,682 0,374 0,065 - 0,318 0,044 0,001 CL  +0,759 CF  +1,004 
 
8/3 7/4*                     Eq.:  +0,827 ( -0,177) 
       0,645 0,388 0,081 - 0,355 0,077 0,004 CL  +0,677 CF  +0,827

With three blots on the bar a white backlash is unlikely.

The 7-point seems to be of strategic value:

Black to Play 5-4

Code:

8/4* 8/3                     Eq.:  +0,859 
       0,664 0,399 0,083 - 0,336 0,082 0,007 CL  +0,721 CF  +0,859 
    
23/18 7/3                    Eq.:  +0,845 ( -0,014) 
       0,639 0,350 0,061 - 0,361 0,061 0,002 CL  +0,625 CF  +0,845

It is important for priming purposes, and blocking 6s, as is made clear by the drop in relative equity difference when moving the 1w-point to 2:

Black to Play 5-4

Code:

23/18 7/3                    Eq.:  +0,769 
       0,627 0,335 0,032 - 0,373 0,075 0,004 CL  +0,541 CF  +0,769 
   
8/4* 8/3                     Eq.:  +0,685 ( -0,085) 
       0,622 0,369 0,043 - 0,378 0,097 0,008 CL  +0,550 CF  +0,685

The original equity difference is 0,17.

The 6-point pile makes hitting loose also less desirable. Moving the pile to the 8-point.

Code:

23/20 8/3                    Eq.:  +1,008 
       0,692 0,364 0,060 - 0,308 0,050 0,002 CL  +0,756 CF  +1,008 
 
8/3 7/4*                     Eq.:  +0,931 ( -0,078) 
       0,688 0,405 0,078 - 0,312 0,075 0,006 CL  +0,778 CF  +0,931 

23/18 6/3                    Eq.:  +0,896 ( -0,112) 
       0,665 0,327 0,047 - 0,335 0,060 0,002 CL  +0,642 CF  +0,896

There is little cubeless difference, so hitting loose has moved up. If everything goes well, priming gets a lot easier now.

Another factor is that white still has an opportunity to make the 5w-point in case black has managed to make the 3 and 4-points. See the following position:

Black to Play 4-2

Code:

13/9 6/4                     Eq.:  +1,042
       0,701 0,407 0,076 - 0,299 0,048 0,002 CL  +0,836 CF  +1,042
  
8/4 7/5*                     Eq.:  +0,960 ( -0,082)
       0,687 0,429 0,091 - 0,313 0,070 0,006 CL  +0,817 CF  +0,960

With black's position hitting loose is only (slightly) profitable when white has no homeboard, which I think is pretty unthinkable at this stage:

Code:

8/3 7/4*                     Eq.:  +1,055 
       0,672 0,445 0,109 - 0,328 0,048 0,002 CL  +0,849 CF  +1,055 

23/18 6/3                    Eq.:  +0,993 ( -0,062) 
       0,655 0,409 0,084 - 0,345 0,039 0,001 CL  +0,764 CF  +0,993

Or, when there is more ammo and a better spread of builders:

Code:

8/3 7/4*                     Eq.:  +1,216
       0,758 0,470 0,095 - 0,242 0,044 0,002 CL  +1,035 CF  +1,216
 
23/20 8/3                    Eq.:  +1,136 ( -0,080)
       0,735 0,411 0,068 - 0,265 0,035 0,001 CL  +0,913 CF  +1,136

If white hits back, he can easily do so in return, and he will even be contented if he manages to create a 4-prime.

Conclusion:
In a situation like this black should never hit loose, unless he has a good spread of builders.

Quote

07-30-2015 , 05:28 AM

#340

yogiman

adept

Join Date: Jun 2012 Posts: 784

Position ID: 2jYxgAU73GMAQA
Match ID: cAkKAAAAAAAE

White - Pips 129

Black - Pips 99
Black to Play 4-2
Created with www.BGdiagram.com

Quote

07-30-2015 , 05:48 AM

#341

Karol Szczerek

enthusiast

Join Date: Mar 2015 Posts: 92

B/23* is obviously forced.

With all those blots lying around I'd play the bold 7/3. It puts our checkers to most efficient use, keep flexible and robust formation, give a chance to blitz if the opp dances.

10/6 breaks a blocking/attacking point, while leaving the same number of shots as 7/3 (11 numbers).

6/2 kills another checker (it's 6th already !!!), leaving a critically non-flexible position.

Quote

07-30-2015 , 09:13 AM

#342

bleep69

grinder

Join Date: Sep 2008 Posts: 483

This one looks easy, which makes me very suspicious, but I'd play B/23*, 7/3. The one move is forced, and the other move just doesn't have any other options either.

Quote

07-31-2015 , 11:25 AM

#343

yogiman

adept

Join Date: Jun 2012 Posts: 784

Code:

bar/23* 7/3                  Eq.:  -0,087
       0,448 0,209 0,003 - 0,552 0,165 0,006 CL  -0,062 CF  -0,087
      
bar/23* 6/2                  Eq.:  -0,181 ( -0,094)
       0,427 0,187 0,002 - 0,573 0,148 0,005 CL  -0,109 CF  -0,181

If white doesn't enter (25%), she will next turn have a pass thanks to her blot on the 17-point. (Without that blot, slotting is still preferrable). If black is hit, and subsequently doesn't enter(30%x45%=15%), it will be too good to double for white. If he does enter, white will not double because his checkers are too far away. So the immediate mishap for both sides after slotting looks about equal. However, the merit is great, because black will be able to create a 4-board with ease. The reason that the cubeless difference is only 0.5, is maybe that black needs a 3 or 4 to cover to cover next turn (60%), but could run into problems if he doesn't succeed in this, or black doesn't manage to enter for a second time.

Notice that in the previous problem it was wrong to place a blot before the checker on the bar, whereas here it is right. It's not only that the alternative is to kill the checker, but there is less to lose for black, as he is in dire straits anyway.

Another difference with the previous problem is that a better spread of pointmakers makes slotting less desirable.
10 to 9:

Code:

bar/23* 7/3                  Eq.:  -0,046
       0,460 0,222 0,004 - 0,540 0,151 0,006 CL  -0,011 CF  -0,046
     
bar/23* 6/2                  Eq.:  -0,093 ( -0,047)
       0,450 0,201 0,003 - 0,550 0,137 0,005 CL  -0,038 CF  -0,093

Black's 9-point can help in making the 3-point later. Slotting is less necessary.
That's why slotting is maybe not so obvious:

Code:

bar/23* 6/2                  Eq.:  +0,071
       0,484 0,211 0,003 - 0,516 0,122 0,004 CL  +0,057 CF  +0,071

bar/23* 7/3                  Eq.:  +0,027 ( -0,044)
       0,481 0,219 0,004 - 0,519 0,143 0,005 CL  +0,038 CF  +0,027

Black has a better potential to make the 3-point later.

Also not with the killed checker:
10 to 6:

Code:

bar/23* 6/2                  Eq.:  +0,031
       0,469 0,219 0,002 - 0,531 0,098 0,003 CL  +0,057 CF  +0,031
    
bar/23* 7/3                  Eq.:  -0,072 ( -0,103)
       0,447 0,214 0,003 - 0,553 0,137 0,005 CL  -0,031 CF  -0,072

In the next two positions the cubeless equity difference is about the same as in the original position, namely 0.5, but the cubeful equity difference has increased.

A second killed checker makes that slotting moves up in value:

Code:

bar/23* 7/3                  Eq.:  -0,193
       0,411 0,209 0,003 - 0,589 0,186 0,008 CL  -0,159 CF  -0,193
   
bar/23* 10/6                 Eq.:  -0,258 ( -0,066)
       0,390 0,197 0,002 - 0,610 0,171 0,007 CL  -0,199 CF  -0,258
  
bar/23* 6/2                  Eq.:  -0,332 ( -0,139)
       0,393 0,184 0,002 - 0,607 0,173 0,007 CL  -0,209 CF  -0,332

The increase in cube efficiency likely has to do with the volatility of the position. If black is hit, now or later, he will have less opportunity to create the 4-board. Hence, white will have a stronger cube or recube.

7 to 24:

Code:

bar/23* 7/3                  Eq.:  -0,750
       0,318 0,147 0,003 - 0,682 0,260 0,015 CL  -0,489 CF  -0,750
    
bar/23* 6/2                  Eq.:  -0,928 ( -0,178)
       0,295 0,119 0,002 - 0,705 0,264 0,013 CL  -0,565 CF  -0,928

Hopefully the same explanation as in the previous position.

Conclusion:
Black has a deplorable homeboard, and, due to his blot behind the strong white offense desperately needs to do something about it. Killing a checker reduces his flexibility to create that necessary extra point in his homeboard.

Quote

08-02-2015 , 03:37 AM

#344

yogiman

adept

Join Date: Jun 2012 Posts: 784

Position ID: tpwZAwjYtokBAw
Match ID: cAkKAAAAAAAE

White - Pips 116

Black - Pips 136
Black to Play 4-2
Created with www.BGdiagram.com

Quote

08-02-2015 , 06:15 AM

#345

Karol Szczerek

enthusiast

Join Date: Mar 2015 Posts: 92

Being behind in the race, I certainly don't want to break the anchor.
My strategy is to attack.

One way is to hit now. 7/5 7/3* looks to be the best one. We break the 5-prime while we don't have a stronger board though. Opp has 6 crushing hits (which cover his 4-pt. blot): 32, 34, 36.

The other way is to bring more builders and slot the back of the prime with 13/9 13/11. We're exposed to 7 crushers: 61, 62, 64, 66, but I feel our gains are much stronger.

If we're not hit we can cash pretty easily (or maybe we are even too good). After the hitting play, only after opp dance we will have a strong double (probably close to pass). It doesn't mean that the access to cube is key here, but it helps to see the equity level of both plays.

It seems to be one of those cases, where slotting with 13/9 13/11 is best.

Quote

08-02-2015 , 11:10 AM

#346

uberkuber

veteran

Join Date: Jul 2009 Posts: 3,032

13/9 13/11 is my play as well, but couldn't explain it like Karol.
Didn't even consider 7/5 7/3* because I didn't consider breaking the 5-prime.

Quote

08-03-2015 , 04:59 AM

#347

yogiman

adept

Join Date: Jun 2012 Posts: 784

White - Pips 116

Black - Pips 136

Code:

13/11 13/9                   Eq.:  +0,565
       0,674 0,148 0,004 - 0,326 0,083 0,002 CL  +0,416 CF  +0,565
   
10/4                         Eq.:  +0,497 ( -0,068)
       0,615 0,153 0,005 - 0,385 0,060 0,002 CL  +0,326 CF  +0,497
   
7/5 7/3*                     Eq.:  +0,422 ( -0,143)
       0,599 0,188 0,006 - 0,401 0,108 0,003 CL  +0,281 CF  +0,422

In order for the move to be viable, roughly speaking the gain for black in case of not being hit must be greater than the gain for white after hitting. If white hits, black's game is in many cases far from over. If white doesn't hit, black has a 60% chance to cover, and in the other 40% of the cases will hit loose or make a point on white's head. If white is not in possession of the cube, it's obvious he will double her out.
More specific. The chance that white throws a 6 versus the chance he does not throw a 6 is 1 : 2. Hence, the 1 point that black scores counts double, and in spite of the many singles and several gammons that white will win, we know that after a hit she will not come close to the 2 points necessary to break even. So we can guess that it is a strong move, but is it better than the safe play? The fact is that black has already got a good winning position.
In case of a high volatility move I simply rely on the bot. And this is what the bot tells me:

If black is ahead in the pipcount, there is no reason to volunteer a shot.

White - Pips 150

Black - Pips 138

Code:

7/5 7/3*                     Eq.:  +0,252
       0,520 0,234 0,006 - 0,480 0,088 0,004 CL  +0,189 CF  +0,252
 
10/4                         Eq.:  +0,185 ( -0,067)
       0,515 0,190 0,004 - 0,485 0,071 0,003 CL  +0,150 CF  +0,185

13/11 13/9                   Eq.:  +0,128 ( -0,124)
       0,501 0,191 0,006 - 0,499 0,079 0,003 CL  +0,117 CF  +0,128

White - Pips 152

Black - Pips 136

Code:

10/4                         Eq.:  +0,979
       0,757 0,207 0,008 - 0,243 0,040 0,001 CL  +0,687 CF  +0,979

13/11 13/9                   Eq.:  +0,899 ( -0,080)
       0,757 0,188 0,007 - 0,243 0,051 0,001 CL  +0,656 CF  +0,899

But otherwise, we can play it routinely.

Black is on 23-point behind a 5-prime:

Code:

13/11 13/9                   Eq.:  -0,172
       0,467 0,083 0,003 - 0,533 0,178 0,009 CL  -0,167 CF  -0,172

10/4                         Eq.:  -0,371 ( -0,199)
       0,399 0,078 0,003 - 0,601 0,137 0,006 CL  -0,264 CF  -0,371

You might think that the damage will be greater in case black is hit, but his two rear checkers are already almost serving a life sentence. The way to escape is by throwing 55 or by priming.

The position has shifted, and black plays 54

Black to Play 5-4

Code:

10/6 7/2*                    Eq.:  +0,620
       0,665 0,283 0,007 - 0,335 0,083 0,002 CL  +0,533 CF  +0,620
  
13/9 13/8                    Eq.:  +0,598 ( -0,023)
       0,693 0,202 0,005 - 0,307 0,067 0,002 CL  +0,524 CF  +0,598

Black to Play 5-4

Code:

13/9 13/8                    Eq.:  -0,236
       0,437 0,098 0,003 - 0,563 0,165 0,009 CL  -0,198 CF  -0,236

10/6 7/2*                    Eq.:  -0,304 ( -0,068)
       0,416 0,150 0,004 - 0,584 0,186 0,011 CL  -0,212 CF  -0,304

The relative value is a lot less, because hitting is a strong alternative.

Black is playing a twoway-game:

White - Pips 116

Black - Pips 176

Code:

13/11 13/9                   Eq.:  -0,202
       0,502 0,099 0,004 - 0,498 0,241 0,025 CL  -0,159 CF  -0,202
 
24/20 10/8                   Eq.:  -0,265 ( -0,064)
       0,454 0,094 0,004 - 0,546 0,205 0,004 CL  -0,203 CF  -0,265

White has 2 checkers behind:

White - Pips 132

Black - Pips 136

Code:

13/11 13/9                   Eq.:  +0,718
       0,683 0,131 0,004 - 0,317 0,069 0,002 CL  +0,429 CF  +0,718
    
10/4                         Eq.:  +0,666 ( -0,053)
       0,674 0,124 0,004 - 0,326 0,053 0,001 CL  +0,421 CF  +0,666

If white escapes a checker, he has done just halve the job. So the relative value of safe play rises.

Black has just a 4-prime, and a 5 is not enough for white:

White - Pips 116

Black - Pips 156
Black to Play 4-2

Code:

20/14                        Eq.:  +0,055
       0,521 0,098 0,004 - 0,479 0,136 0,003 CL  +0,006 CF  +0,055
      
13/11 13/9                   Eq.:  +0,047 ( -0,008)
       0,525 0,092 0,003 - 0,475 0,169 0,005 CL  -0,029 CF  +0,047

White - Pips 116

Black - Pips 149

Code:

13/9 8/6                     Eq.:  +0,243
       0,575 0,110 0,004 - 0,425 0,127 0,003 CL  +0,133 CF  +0,243
 
13/7                         Eq.:  +0,073 ( -0,170)
       0,521 0,094 0,003 - 0,479 0,095 0,002 CL  +0,041 CF  +0,073

Conclusion:
Slotting behind the blockage is a high volatility move meant to full-prime white. The more black lags behind, the more there is to be turned around, and the greater the relative value of slotting is.

Quote

08-04-2015 , 12:50 PM

#348

yogiman

adept

Join Date: Jun 2012 Posts: 784

Position ID: zbyBwQCuOYMBAw
Match ID: cAkJAAAAAAAE

White - Pips 113

Black - Pips 117
Black to Play 2-2
Created with www.BGdiagram.com

Quote

08-04-2015 , 02:03 PM

#349

_Z_

adept

Join Date: Jul 2004 Posts: 720

Black would like to keep pressure on White by keeping a lot of contact in the outfield, but 13/11(2) 8/6(2) looks kind of stacky and stripped. 13/11(2) 6/4 3/1 is even uglier. And the timing wouldn't be great after either of these plays -- White can safely play from the 6 point if he rolls small and he can pretty safely from the 13 point for the next couple turns if he rolls medium/big. Meanwhile Black might be left without a safe play in the next turn or two, especially after 8/6(2). I guess he could keep maximum pressure on with 8/4(2), but that's ugly too and now Black really don't have a good play next turn.

So I would just try 13/9(2), which does take some pressure off White's 18 point, but it keeps the position clean, and it will leave Black with constructive plays over the next few rolls.

Quote

08-07-2015 , 04:54 AM

#350

bleep69

grinder

Join Date: Sep 2008 Posts: 483

What a grotty roll. With the aim of keeping contact, I'd play 13/11 (2), 3/1 6/4. I'm a little worried about moving the checkers in our base so far forward, but everything else seems to play into white's hands.

Quote

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