Position # 32

[PersianLord]

Position information:

Pip-count: Red 20-40 White
Score:       Red   4-4   White
Match:                 7-pointer





First make your choice and then read on.

Spoiler

Here victory is guaranteed for red, but does it mean that he should not care about furtue moves? No, a serious backgammon player never gives away even his slightest chance to gain equity.

In this position, most of players would move 7/5-4/3-1/off, thinking that this move is in line with the "distribution" principle. But that's wrong, because as said, red can not lose this game even if he plays as terrible as one would imagine. Thus distribution does not matter here and instead red should focus to win a much valuable gammon and finish white off.

But how can red accomplish that? The answer is the ugly-looking move of 7/4-1/off. After this move, all of the red's 4 checkers will be stacked on his 4-pt, yet he will have more gammon chances, because now he will has another roll that will win a gammon for him: 5-5, while with the more pure and nice-looking move of 7/5-4/3-1/off, this roll will be almost useless. Here's GNUBG's analysis:

    1. Cubeful 2-ply    7/4 1/off                    Eq.:  +1.097
       100.0%  10.2%   0.0% -   0.0%   0.0%   0.0%
     
    2. Cubeful 2-ply    7/5 4/3 1/off                Eq.:  +1.082 ( -0.015)
       100.0%   8.6%   0.0% -   0.0%   0.0%   0.0%
     
    3. Cubeful 2-ply    7/6 4/3(2) 1/off             Eq.:  +1.058 ( -0.039)
       100.0%   6.0%   0.0% -   0.0%   0.0%   0.0%
     
    4. Cubeful 2-ply    7/6 4/2 1/off                Eq.:  +1.056 ( -0.041)
       100.0%   5.9%   0.0% -   0.0%   0.0%   0.0%
       
    5. Cubeful 2-ply    7/6 4/2 4/3                  Eq.:  +1.027 ( -0.071)
       100.0%   2.8%   0.0% -   0.0%   0.0%   0.0%
     

As can be seen, the difference between the best moves are relatively small, because the only roll that can make that difference is the 5-5 rolls with just ~3% probability. But as said, a serious backgammon player should not give away even the slightest chances and in order to do that, sharp mathematical skills are required, as in the above position.

[close]

[spielberg]

Spoiler

This is a very easy one - all you need recognise is the massive value of a gammon for Red

[close]

[PersianLord]

Spoiler

This is a very easy one - all you need recognise is the massive value of a gammon for Red

[close]

One may recognize the massive value of a gammon for red and still be unable to recognize the best move.

By the way, I can stop posting my positions if they're considered to be too easy.

Regards

[socksey]

Maybe easy, but I got it wrong.   

Keep them coming, PL.   

socksey



"What if everything is an illusion and nothing exists? In that case, I definitely overpaid for my carpet." - Woody Allen

[nixo]

Yes PL go on posting positions !

What is the most interesting is the comments. One can easily find a best move but the harder is to put words on it and explain why it is the best choice.
So I must thank you again 

But one vcan admit that this one was quite easy 

sorry for my bad english

[PersianLord]

Yes PL go on posting positions !

What is the most interesting is the comments. One can easily find a best move but the harder is to put words on it and explain why it is the best choice.
So I must thank you again 

But one vcan admit that this one was quite easy 

sorry for my bad english

Thanks dear friend for the kind words 

Well, after Steve got the last problem right just because he knew that the "usual move" should had been discarded, I decided to post an easy one!  Yet, we've got just 1 correct answer till now.

And also I would say that I'm definitly not the one that his comments may be regarded as worth-reading. I just play gnubg, and whenver I come across an interesting position, I post it in my blog, and occasionally also here. This has been very useful at least for myslef, cuz I can remeber patterns better and cuz I review my blog from time to time.

My skill level, according to gnubg, is advanced on mean, sometimes I get expert sometimes intermediate, but on average I get advanced remarks. So you may consult a more skillful player if you want more accurate and more detailed analysis.

Regards

PS: The key roll in this position is 4-4, not 5-5. Execuse me for the mistake.

[playBunny]

  I got the last two wrong [warning: feeble excuses ahead] because I answered too quickly and was tired [end of excuses, did you believe them? ] .. so my confidence is restored with this easy one.

[blitzxz]

Actually red can still lose here...    It's just very unlikely. For example 66 every time would mean that white can bear off in 5 rolls and 2-1 every time for red would take 6 rolls after correct move. And white's on roll so it's not even close. 

[PersianLord]

Actually red can still lose here...    It's just very unlikely. For example 66 every time would mean that white can bear off in 5 rolls and 2-1 every time for red would take 6 rolls after correct move. And white's on roll so it's not even close. 

Yes, and actually white will want just 1 6-6 doublet, because after the first 6-6, any 5-5,4-4 and 3-3 will suffice and after the second doublet, actually EVERY doublet will do te job. But also this will happen if red rolls 2-1 all the time, which is very unlikely as you said, but GNUBG should have reflected this fact in it's analysis IMHO.

Nice point BTW.

Regards

[spielberg]

By the way, I can stop posting my positions if they're considered to be too easy.

Of course not - as I said once before all problems have value regardless of their difficulty, largely because of the quality of the explanations from the experts. It's of much, much greater value to know why a move is correct than which is the correct one.