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3 4 9 0 |
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The following Quiz is constructed primarily with positions from The Danish Backgammon Federation's Discussion Forum. The quiz assumes no Jacoby rule (most of the positions are from matches in wich the score does not affect the correct checkermove). I have looked for positions that I find interesting and where people have argued for large mistakes. Most of the wrong answers are blunders but this does not make the quiz easy!
The questions are structured with answering possibilities to the right of the position. If you scroll down an analysis and an answer can be found under each position. Be careful not to scroll down to the analysis before you have made an answer. I have included GNU Backgammon 0.13 4-ply evaluation of all the answers.
Problem 0
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20/15 4/3 20/15 3/2 20/14 |
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As many might have guessed this position is constructed and therefore the answer is easy. Actually blue needs a high gammon price (in this case >0.8) to make the creative checker move correct. I have mostly included it here as an example because many browsers will already be scrolled down to the answer.
1. Cubeful 4-ply 20/15 3/2 MWC: 61,17%
0,921 0,302 0,015 - 0,079 0,000 0,000
4-ply cubeful
2. Cubeful 4-ply 20/14 MWC: 60,88% ( -0,28%)
0,941 0,277 0,012 - 0,059 0,000 0,000
4-ply cubeful
3. Cubeful 4-ply 20/15 4/3 MWC: 60,77% ( -0,40%)
0,941 0,275 0,012 - 0,059 0,000 0,000
4-ply cubeful
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Problem 1
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24/13 9/3* 8/3 |
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If in doubt - hit. This is an old saying in backgammon that hold some wisdom. Hopefully blue is not doubting in this position. With this great roll he can solve his most presing problem. The lonely back checker! With a hit blue can make the fourth point in his home land wich is very desireble but he will also give up two great points in his out field. These points are sufficiently good to secure a drop after many of white's rolls. Normally blue will try to seek out the volatile position when he is near a double but this is an example of a position where that is wrong. The reason is that he has such a good position that he can probably double white out after his roll anyway. Seeking volatility will just give white a larger take in some positions (be extremly carefull with this line of argument since the reverse is often true).
1. Cubeful 4-ply 24/13 Eq.: +0,671
0,669 0,107 0,001 - 0,331 0,042 0,001
4-ply cubeful
2. Cubeful 4-ply 9/3* 8/3 Eq.: +0,555 ( -0,116)
0,609 0,300 0,007 - 0,391 0,118 0,007
4-ply cubeful
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Problem 2
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13/10(2) 11/8 9/6 13/7(2) 11/8 10/1* 10/1* 9/6 |
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As you can see blue chose the wrong plan and white rolled a good 1-1. Now he has a choice between hitting, consolidating his position or makeing the bar. I think it is easy to see that the consolidating idear is wrong. White has too many threats. Many will automatically make the bar but this is also wrong. The reason is that blue commited himself to a more agressive plan with his last move. The back checker is still blue's big problem. By making the bar blue will give white an exelent chance of working on captureing his back checker with the best timing and even six great non copied rolls that hits in blue's out field and leaves the dangerzone. Besides that now blue does want a volatile position to access the cube.
1. Cubeful 4-ply 10/1* 9/6 Eq.: +0,334
0,562 0,313 0,005 - 0,438 0,145 0,009
4-ply cubeful
2. Cubeful 4-ply 11/8 10/1* Eq.: +0,285 ( -0,048)
0,537 0,274 0,004 - 0,463 0,144 0,007
4-ply cubeful
3. Cubeful 4-ply 13/10(2) 11/8 9/6 Eq.: +0,193 ( -0,141)
0,526 0,196 0,004 - 0,474 0,091 0,003
4-ply cubeful
4. Cubeful 4-ply 13/7(2) Eq.: +0,146 ( -0,188)
0,519 0,217 0,007 - 0,481 0,148 0,008
4-ply cubeful
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Problem 3
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24/22 9/6 24/22 6/3 9/7 6/3 9/4 6/1* |
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This is thematic. Slotting is often correct in potential backgames. Many will recognize slots behind their prime but you often also like to slot points in front of your prime. Although this is not a backgame it might go that way. In that case blue is very much in need of timing. If he want his front game plans to succeed he will have to seek some luck. Slotting points is one way of increasing this chance given white does not hit. Look for gameplans. Here you have two and both bennefits from a slot.
1. Cubeful 4-ply 9/7 6/3 Eq.: -0,258
0,494 0,099 0,002 - 0,506 0,252 0,031
4-ply cubeful
2. Cubeful 4-ply 9/4 Eq.: -0,391 ( -0,133)
0,443 0,094 0,002 - 0,557 0,252 0,026
4-ply cubeful
3. Cubeful 4-ply 24/22 6/3 Eq.: -0,514 ( -0,256)
0,431 0,090 0,002 - 0,569 0,337 0,020
4-ply cubeful
4. Cubeful 4-ply 24/22 9/6 Eq.: -0,562 ( -0,303)
0,396 0,082 0,002 - 0,604 0,281 0,013
4-ply cubeful
5. Cubeful 4-ply 6/1* Eq.: -0,801 ( -0,543)
0,372 0,066 0,001 - 0,628 0,304 0,036
4-ply cubeful
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Problem 4
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23/22 3/1* 23/21 11/10 23/21 3/2 11/10 3/1* 6/4 5/4 |
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Some might like a 5 point board some the 21 point. That is very wrong. Blue has a 4 point board against white's 2 points and access to the cube. He has to exploit this now that he has the chance. Hit and seek out the volatile position where you can use your access to the cube. In this position the hit is even correct without access to the cube but of course by less (0.08).
1. Cubeful 4-ply 23/22 3/1* Eq.: +0,392
0,568 0,239 0,003 - 0,432 0,115 0,005
4-ply cubeful
2. Cubeful 4-ply 11/10 3/1* Eq.: +0,350 ( -0,043)
0,547 0,251 0,004 - 0,453 0,138 0,011
4-ply cubeful
3. Cubeful 4-ply 23/21 11/10 Eq.: +0,270 ( -0,123)
0,548 0,173 0,002 - 0,452 0,075 0,003
4-ply cubeful
4. Cubeful 4-ply 6/4 5/4 Eq.: +0,240 ( -0,152)
0,543 0,217 0,006 - 0,457 0,115 0,004
4-ply cubeful
5. Cubeful 4-ply 23/21 3/2 Eq.: +0,227 ( -0,166)
0,545 0,149 0,002 - 0,455 0,080 0,003
4-ply cubeful
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Problem 5
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13/7 6/4* 13/5 8/6 8/2 8/2 6/4* |
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Blue need to take the initiative here by hitting and unstacking his most heavy point. He will then need to look for where he can play his 6. There might be a long game in front of him. This means that blue want to hold on to his position and the midpoint. This point is often underestimated. It connects your back men with the rest of your game. Without it your opponent can grab the outer board control, leave your homeland by slotting points in your outfield and you can not use it to escape checkers from your opponent's homeland. This all means that blue need to slot his 2 point too in this position and unstack the heavy 8 point.
1. Cubeful 4-ply 8/2 6/4* Eq.: -0,430
0,410 0,148 0,007 - 0,590 0,280 0,035
4-ply cubeful
2. Cubeful 4-ply 13/7 6/4* Eq.: -0,668 ( -0,238)
0,390 0,133 0,007 - 0,610 0,330 0,060
4-ply cubeful
3. Cubeful 4-ply 13/5 Eq.: -0,725 ( -0,294)
0,332 0,101 0,004 - 0,668 0,227 0,018
4-ply cubeful
4. Cubeful 4-ply 8/6 8/2 Eq.: -0,788 ( -0,358)
0,333 0,104 0,003 - 0,667 0,256 0,024
4-ply cubeful
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Problem 6
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8/6 5/2 8/5 6/4 8/3 7/4 6/4 6/4 5/2 |
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This is clearly a timing battle and blue has to hold on to as much timing and luck as he can to win it. This meens that white's high rolls should play on his side of the board. This clearly rules out taking the 4 point since that will make white's 6s much better. Stacking the 5 point is clearly not a good idea since blue's position will crunch up more quickly that way. This leaves us with the passive play 8/3 and slotting the 2 point. The pasive play stacks blue's checkers and is bad for your timing. E.g. it is harder to live with a 6 next time. By slotting blue can roll his prime forward on white's worst rolls (the ones that does not leave the 1 point) and blue will have a real chance of winning the timing battle. Slotting blue's 4 point too is even more aggressively trying to exploit this. You do not like to get hit but the rolls hitting you are very good anyway.
1. Cubeful 4-ply 6/4 5/2 Eq.: -0,559
0,351 0,115 0,007 - 0,649 0,212 0,010
4-ply cubeful
2. Cubeful 4-ply 8/6 5/2 Eq.: -0,594 ( -0,035)
0,318 0,104 0,005 - 0,682 0,147 0,006
4-ply cubeful
3. Cubeful 4-ply 8/3 Eq.: -0,699 ( -0,140)
0,290 0,096 0,005 - 0,710 0,124 0,005
4-ply cubeful
4. Cubeful 4-ply 8/5 6/4 Eq.: -0,715 ( -0,156)
0,309 0,100 0,005 - 0,691 0,178 0,009
4-ply cubeful
5. Cubeful 4-ply 7/4 6/4 Eq.: -0,777 ( -0,218)
0,281 0,088 0,004 - 0,719 0,133 0,005
4-ply cubeful
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Problem 7
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bar/24(2) 6/5(2) bar/23*/22 bar/24 bar/23*(2) |
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Wow. If you got this wrong you made a huge blunder. Blue hold 3 checkers deep in his home land. He gains much more by concentrating on this task than from circulating more checkers with this roll. Blue has to unstack his heavy point and get the most valuable point on the board. The race and tempo gain from hitting is not nearly enough to compete with that. Watch out for automatic hits. Many people hit the deepest checker if they can and look for a way to play the rest of the roll. Find a gameplan and play according to that.
1. Cubeful 4-ply bar/24(2) 6/5(2) Eq.: +0,681
0,663 0,250 0,020 - 0,337 0,125 0,006
4-ply cubeful
2. Cubeful 4-ply bar/23*/22 bar/24 Eq.: +0,281 ( -0,400)
0,559 0,199 0,017 - 0,441 0,142 0,005
4-ply cubeful
3. Cubeful 4-ply bar/23*(2) Eq.: +0,193 ( -0,487)
0,538 0,191 0,015 - 0,462 0,147 0,006
4-ply cubeful
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Problem 8
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bar/23 21/17 bar/23 18/14 bar/23 6/2* bar/21 4/2* |
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Yes - this is a hit and it is thematic. You often make this kind of hit when you really need to hold on to your opponent or your opponent has a really big threat (as we have and shall see). Blue has a good board and very much want to make use of it now. White has a blot and only 2 points. Why not hit with the 4 then and get a double shot after a dance? The reason is that the 6 point is valuable long term and you get fewer covernumbers after a dance.
1. Cubeful 4-ply bar/21 4/2* Eq.: +0,129
0,701 0,000 0,000 - 0,299 0,166 0,002
4-ply cubeful
2. Cubeful 4-ply bar/23 21/17 Eq.: +0,091 ( -0,038)
0,664 0,000 0,000 - 0,336 0,147 0,001
4-ply cubeful
3. Cubeful 4-ply bar/23 18/14 Eq.: +0,090 ( -0,039)
0,671 0,000 0,000 - 0,329 0,153 0,002
4-ply cubeful
4. Cubeful 4-ply bar/23 6/2* Eq.: -0,076 ( -0,205)
0,638 0,000 0,000 - 0,362 0,218 0,007
4-ply cubeful
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Problem 9
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21/14* 8/3*/1 |
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You almost generally want to hit in the outfield in this type of position. Blue might never pick up that checker if he does not. If white gets off the bar he will crunch up and have less threats. To be hit on the 1 point will rarely be a problem. That winning plan is difficult. The lucky escape after your hit and pass in your homeland is more dangerous.
1. Cubeful 4-ply 21/14* Eq.: +0,907
0,780 0,218 0,003 - 0,220 0,058 0,001
4-ply cubeful
2. Cubeful 4-ply 8/3*/1 Eq.: +0,790 ( -0,117)
0,748 0,218 0,002 - 0,252 0,056 0,001
4-ply cubeful
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Problem 10
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18/16 18/12 18/12 6/4* 18/10 |
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This is quite interesting. Many will find the correct money play which is to hit (owning the cube it is a 0.19 blunder not to). Now why is that a mistake here? The reason is that blue does not benefit from the cube ownership, the extra gammons hitting wins and that he actually loose a very expensive backgammon a significant number of times. Many people might think that I am focusing on the wrong gammons and think that white loosing gammon is very important at this score. This is wrong! At 2 away to 5+ away the doubled gammon price is roughly the same as for money. True that you loose a lot by getting gammoned but the gain from winning is also high (you hit the target).
1. Cubeful 4-ply 18/10 MWC: 70,86%
0,261 0,045 0,000 - 0,739 0,274 0,009
4-ply cubeful
2. Cubeful 4-ply 18/16 18/12 MWC: 69,85% ( -1,00%)
0,231 0,037 0,001 - 0,769 0,276 0,009
4-ply cubeful
3. Cubeful 4-ply 18/12 6/4* MWC: 67,87% ( -2,99%)
0,337 0,140 0,001 - 0,663 0,421 0,065
4-ply cubeful
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I will add some cube problems to this quiz latter. Send comments to m@xfriis.dk.
Copyright © 2003 by Peter Max Friis Jensen
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