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Old 03-16-2020, 07:20 PM
Enderw24 is offline
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Backgammon rules question


A player rolls a 6 and a 2. Suppose the game state is such that thereís currently no legal 6 moves to make. There are two potential 2 moves to make. One of them would continue to make any 6 move illegal. The other would allow a 6 move.

Is there a requirement that both dice numbers be utilized if thereís any possibility to do so? In other words, forcing the 2 that would open up the 6. Or can a player choose to lock themselves out of their second move?
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Old 03-16-2020, 07:34 PM
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Is there a requirement that both dice numbers be utilized if there’s any possibility to do so?
Yes.
https://www.fgbradleys.com/rules/Backgammon_Rules.pdf
Quote:
A player must use both numbers of a roll if this is legally possible (or all four numbers of a double). When only one number can be played, the player must play that number. Or if either number can be played but not both, the player must play the larger one. When neither number can be used, the player loses his turn.
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Old 03-16-2020, 11:37 PM
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So this appears to answer it but thereís still wiggle room. A player must use both rolls when itís legally possible it says. But at the start it wasnít legally possible. It was only possible to play the smaller number.

What I ended up doing was letting my daughter move the two where she wanted and thus keeping the 6 impossible. Otherwise sheíd have had to open herself up where I could likely capture her piece next turn.
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Old 03-17-2020, 04:16 AM
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Originally Posted by Enderw24 View Post
So this appears to answer it but thereís still wiggle room. A player must use both rolls when itís legally possible it says. But at the start it wasnít legally possible. It was only possible to play the smaller number.
No wiggle room - you have to consider the whole roll. If it's legally possible to play both numbers (even if the order you play them is forced), you must do so.

It was kind of you to give your daughter the benefit of the doubt, as you weren't sure. But if I were you, I'd go back and explain the definitive answer, in case it comes up again. It's not uncommon in backgammon for it to be preferably to 'pass' rather than move if that were allowed, this is just a special case of that.
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Old 03-17-2020, 04:50 AM
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Originally Posted by Dead Cat View Post
It was kind of you to give your daughter the benefit of the doubt, as you weren't sure. But if I were you, I'd go back and explain the definitive answer, in case it comes up again. It's not uncommon in backgammon for it to be preferably to 'pass' rather than move if that were allowed, this is just a special case of that.
As a chess coach, I agree that you should stick carefully to the rules of every game, even when playing beginners.

I remember teaching chess to a group of 7-9 year olds in a school, when one of them said "The horse can't move backwards!"
After investigating, it turned our their uncle had given them some muddled lessons.

I had to tread carefully, since you don't want to:

- embarrass the child
- 'show up' an uncle (even if they are wrong.)
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Old 03-17-2020, 04:24 PM
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I confess, I'm an infrequent player but under what circumstances could an initial move of 2 make a previously impossible move of 6, possible? I think I'm missing something obvious here.
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  #7  
Old 03-17-2020, 04:32 PM
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Originally Posted by penultima thule View Post
Yes.
https://www.fgbradleys.com/rules/Backgammon_Rules.pdf

A player must use both numbers of a roll if this is legally possible (or all four numbers of a double). When only one number can be played, the player must play that number. Or if either number can be played but not both, the player must play the larger one. When neither number can be used, the player loses his turn.
Huh. I knew the rule that you had to use the whole roll if possible, but I never knew (and neither did anyone I ever played) that if you could play either but not both that you had to play the larger. I assume that occurs pretty infrequently though.

Last edited by muldoonthief; 03-17-2020 at 04:32 PM.
  #8  
Old 03-17-2020, 05:09 PM
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Originally Posted by Novelty Bobble View Post
I confess, I'm an infrequent player but under what circumstances could an initial move of 2 make a previously impossible move of 6, possible? I think I'm missing something obvious here.
I'm no backgammon player but I assume counter A has a block 6 and 8 spaces away, counter B has a block 6 spaces away but not 8. You would prefer to move counter a 2 and pass, but cannot because the rule is you have to move counter B if that's the only way to use them both.
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Old 03-18-2020, 03:09 AM
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Originally Posted by Calavera View Post
I'm no backgammon player but I assume counter A has a block 6 and 8 spaces away, counter B has a block 6 spaces away but not 8. You would prefer to move counter a 2 and pass, but cannot because the rule is you have to move counter B if that's the only way to use them both.
Actually I see what I've done here, I was assuming from the OP that they are talking about moving one counter 2 moves so that it would open up a previously illegal 6 move for the other counter. I couldn't see how that would happen (and still don't think it could) but your explanation is indeed valid and it is the way I understand the game.

Not bad wording on the OP's part but bad reading on mine.
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  #10  
Old 03-18-2020, 06:05 AM
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Originally Posted by muldoonthief View Post
Huh. I knew the rule that you had to use the whole roll if possible, but I never knew (and neither did anyone I ever played) that if you could play either but not both that you had to play the larger. I assume that occurs pretty infrequently though.
Yes, unlike the situation in the OP, this is pretty rare. Here is a possible position where it could come up (Xs represent checkers of one colour, moving right to left, Os represent the other colour, moving left to right):

Code:
X
X  X  X     X  X     X   X 
X  X  X     X  X     X   X  O
15 16 17 18 19 20 21 22 23 24
In the diagram, assume O's 14 other checkers are all on their 3-point or less (on the other side of the board, not shown), and they are to play a roll of 6-3. They can move the checker shown 3 spaces, or 6 spaces, but not both - so they must move 24-18, using the 6 only. Of course, in this particular situation that would be the best choice anyway, but the rules give no choice in the matter. Hope that makes sense.

A very similar situation can be used to illustrate the OP:

Code:
X
X     X  X  X  X  X      X 
X     X  X  X  X  X      X  O
15 16 17 18 19 20 21 22 23 24
Again assuming all the other O checkers are on the 3-point or less (on the other side of the board, not shown), if O is to play a roll of 6-2 here, they must move the checker shown 24-22-16 (normally notated as just 24-16, but I am adding the intermediate step here to fully illustrate the point). They would not be allowed to move one of the O checkers from the 3-point to the 1-point (3-1), and then claim no 6 is playable. Though again, in this particular situation the latter would be a foolish thing to do even if allowed, whereas in the OP's case this apparently wasn't so.
  #11  
Old 03-18-2020, 08:05 AM
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The same rule was discussed in a 2-years-ago thread:
Quote:
Originally Posted by septimus View Post
There's a possible ambiguity in the rule:
You must take your entire roll if possible.

PHP Code:
 +13-14-15-16-17-18------19-20-21-22-23-24-+     
 |             
O  O |   | O  O  O  O  O    |     
 |                  |   | 
O  O  O  O  O    |
 |                  |   |                  |
 |                  |   |                  |
 |                  |   |                  |
 |                  |
BAR|                  |     
 |                  |   |                  |
 |                  |   |                  |
 |                  |   |                  |
 |                  |   |    
X        O    |     
 |                  |   | 
X  X        O  O |     
 +
12-11-10--9--8--7-------6--5--4--3--2--1-+ 
If X rolls 3-1 in this position he is not allowed to play 6/5 and say "I have no 3." He must find a way to play both 3 and 1 ... and thereby leave three blots!

HOWEVER, if he rolls 6-1 he is NOT required to play 6/0 5/4 and leave two blots. He is allowed to play safe with 6/5/0 ó this is considered "taking the whole roll" even though a pip is wasted with the 6.
(Some of the followuup was in a separate thread.)
  #12  
Old 03-18-2020, 08:17 AM
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Quote:
Originally Posted by septimus View Post
The same rule was discussed in a 2-years-ago thread:
(Some of the followuup was in a separate thread.)
Thanks for that septimus, I don't think I've come up against that in real play and I'm not sure what I would have decided. Probably to use the move that uses the whole of the score but good to know that the alternative is valid in those circumstances.
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Last edited by Novelty Bobble; 03-18-2020 at 08:17 AM.
  #13  
Old 03-18-2020, 03:14 PM
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PHP Code:
 +13-14-15-16-17-18------19-20-21-22-23-24-+     
 | 
o              O |   | X     X  X  X    |     
 | 
o              O |   | X        X  X    |
 |                
|  |  X           X    |
 |                  |   |  
X               |
 |                  |   | 
x                |
 |                  |
BAR|                  |     
 |                  |   |                  |
 |                  |   | 
o                 |
 |                  |   | 
o   O            |
 | 
x              X |   | o   O      O    |     
 | 
x              X |   | O  O  o   O  |     
 +
12-11-10--9--8--7-------6--5--4--3--2--1-+ 
Iím doing this on mobile so Iím trying my best, but hereís the board. My daughter is the X. As you can see thereís no current legal 6. There are multiple 2 moves available. If she chooses 19-21 there will still be no legal 6. But if she chooses 12-14 or 7-9 she can move a 6.

I let her move the 19-21. But youíre all saying thatís not a proper move. Iíll know for next time.
  #14  
Old 03-19-2020, 04:24 AM
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It's not perfect, but that's a remarkably good effort to produce an intelligible full board position from mobile - it took me ages to sort out my much more rudimentary diagrams, using a laptop!

Having resolved the rules question, it's an interesting position to analyse as to whether 7-15 or 12-20 is the best move. Without counting, my intuition is they both leave the same number of shots for O's next role. So I think I'd play 12-20 - it starts the 5 point, and if the shot is missed it is quite likely X will be able to leave no blots next roll. The disadvantage is that it leaves the remaining 2 checkers on the 7 point out in the cold - but these may get a chance to hit any blots that O leaves in the outer boards.
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Old 03-21-2020, 02:57 AM
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How old is your daughter? I think there's a fair chance she knew the rule but was taking advantage of Dad!

Gnu Backgammon shows the chances for each move (though it has to be tricked slightly to consider the illegal move).
19/21 .504 .101 .001 .496 .123 .002
12/20 .432 .109 .002 .568 .182 .008
7/15 .379 .115 .002 .621 .262 .011
As Dead Cat implies, 12/20 wins 43.2% of games compared with 37.9% for 7/15. But your daughter's move wins 50.4% of the time!
  #16  
Old 03-22-2020, 08:05 PM
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Originally Posted by septimus View Post
How old is your daughter? I think there's a fair chance she knew the rule but was taking advantage of Dad!
In general? I totally wouldn't put it past her to try something like that! Here? No, she's 9 and I had just taught her Backgammon the week before. So I believe she was as clueless as I was.
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