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Problems with grabbing opponent's 5 too early
09-02-2012
, 08:09 AM
So, what are you thinking when you encounter positions like these two?
White - Pips 164
Black - Pips 162
41S-21S-43 Black to Play 4-3
White - Pips 158
Black - Pips 162
41S-63S-43 Black to Play 4-3
Black - Pips 162
41S-21S-43 Black to Play 4-3
White - Pips 158
Black - Pips 162
41S-63S-43 Black to Play 4-3
09-03-2012
, 04:07 AM
I hope you enjoyed the positions I posted. They were selected to let you begin to identify some of the features of a position that might suggest not making the advanced anchor. Be careful, though. If you play the quiz factor (QF), you may think that I have chosen only positions where making the anchor is wrong. Perhaps, that is true, but you should (and I think you are) make the play that you would make over the board.
Here is a hint: The top two plays in both positions involve making one 5pt or the other. With this in mind, take a look again at the two positions above, and give a reason for preferring one 5pt over the other.
Below are two more for you to practice on.
.
.
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Here is a hint: The top two plays in both positions involve making one 5pt or the other. With this in mind, take a look again at the two positions above, and give a reason for preferring one 5pt over the other.
Below are two more for you to practice on.
.
White - Pips 161
Black - Pips 162
41S-51S-43 . Black to Play 4-3
Black - Pips 162
41S-51S-43 . Black to Play 4-3
.
White - Pips 160
Black - Pips 162
41S-61P-43 . Black to Play 4-3
Black - Pips 162
41S-61P-43 . Black to Play 4-3
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09-04-2012
, 12:40 AM
09-04-2012
, 05:44 PM
09-04-2012
, 07:03 PM
09-10-2012
, 04:04 AM
10-27-2012
, 09:22 PM
10-30-2012
, 07:19 AM
11-02-2012
, 08:19 AM
This thread began when TreeUnit asked for tips about making the opponent’s 5pt early in a game. “I used to believe that grabbing the opponent’s 5pt, given the opportunity, is standard,” he wrote. “Am I going for it too early?”
Although it is hard to answer these questions without reference to a specific position, I can offer one guideline that I follow almost dogmatically. If your opponent has not make much progress offensively, and you are presented with an opportunity to make either a strong offensive play or an equally strong defensive one (such as grabbing your opponent’s 5pt), it is often correct to go with offense. If your opponent has made a key offensive point, however, or is threatening to do so, then you are often better off choosing defense. In short, offense before defense.
Four third-roll positions were posted to help demonstrate the point. All have Black opening with 41-split (24/23 13/9), and then rolling 43 on the third roll. In between, the opponent White rolls a variety of numbers on the second turn. The first of these is shown below. White played 21-split (24/23 13/11) on his turn.
.
Position 1: Black 41-split, White 21-split, Black to play 43
Black can make either one of the 5pts, his opponent’s or his own, but not both. If Black does not make the anchor on White’s 5pt, then White will have 8 rolls that make it himself: 63 61 31 33 11. With 44, White could make the 5pt, but should pass it up in favor of a stronger play: making his 2pt and 4pt while hitting! White will also be pointing on Black’s head when he rolls 55 or 66. Depending how you count it, something like 25% of the time Black will pay a steep price for passing up the anchor.
That’s enough to tip the balance in favor of defense. The 3-ply XG rollout below has making the anchor on top. Making the 5pt trails by 0.023 points of equity.
Black’s blot on the 9pt will have to fend for itself. It can be hit by 10 numbers: 61 52 43 62 53. White’s 22 and 44 are better played by not hitting.
.
Position 2: Black 41-split, White 63-split, Black to play 43
In the second position, White played 63-split (24/18, 13/10). Now White’s offensive threat is somewhat less. He makes his 5pt with 7 rolls (53 51 31 11). With 33, he should not make his 5pt. He should anchor, and make his 3pt, instead. White still makes a point on Black’s head with 55, but his 66 is better used to make an anchor.
If Black makes the anchor, White will have a direct shot at the 9pt. He hits with 12 numbers: any 2, plus the joker 44. That’s 5.5% more than in Position 1. With 53, White should not hit. Making his 5pt is better.
At the rollout below confirms, Black should play offense here. 43-point (9/5 8/5) beats 43-anchor (24/20 23/20) by 0.042.
.
Position 3: Black 41-split, White 51-split, Black to play 43
In Position 3, White played 51-split (24/23 13/8). Offensively, he is not threatening very much. He can make the 5pt with 4 rolls: 33 31 11. The joker 44 plays well for White. He should skip making the 5pt, and make two points inside, while hitting.
If Black leaves his blot on the 9pt, White can hit it with the same 10 rolls he has in Position 1.
Once again, this is a case of offense beating defense. The 3-ply rollout that follows has 43-point (9/5 8/5) beating 43-anchor (24/20 23/20) by 0.016.
.
Position 4: Black 41-split, White 61-point, Black to play 43
In Position 4, White made his bar point, playing 61-point (13/7 8/7). Perhaps this is the easiest of the four positions. White has only 5 numbers that hit on the 9pt: 62 53 44. Meanwhile, White has blocked Black’s direct exit from the 24pt. Black will have to advance his back checkers before they can jump into the outfield. This is the perfect time to anchor.
The rollout favors anchoring by 0.083.
Although it is hard to answer these questions without reference to a specific position, I can offer one guideline that I follow almost dogmatically. If your opponent has not make much progress offensively, and you are presented with an opportunity to make either a strong offensive play or an equally strong defensive one (such as grabbing your opponent’s 5pt), it is often correct to go with offense. If your opponent has made a key offensive point, however, or is threatening to do so, then you are often better off choosing defense. In short, offense before defense.
Four third-roll positions were posted to help demonstrate the point. All have Black opening with 41-split (24/23 13/9), and then rolling 43 on the third roll. In between, the opponent White rolls a variety of numbers on the second turn. The first of these is shown below. White played 21-split (24/23 13/11) on his turn.
.
Position 1: Black 41-split, White 21-split, Black to play 43
Black can make either one of the 5pts, his opponent’s or his own, but not both. If Black does not make the anchor on White’s 5pt, then White will have 8 rolls that make it himself: 63 61 31 33 11. With 44, White could make the 5pt, but should pass it up in favor of a stronger play: making his 2pt and 4pt while hitting! White will also be pointing on Black’s head when he rolls 55 or 66. Depending how you count it, something like 25% of the time Black will pay a steep price for passing up the anchor.
That’s enough to tip the balance in favor of defense. The 3-ply XG rollout below has making the anchor on top. Making the 5pt trails by 0.023 points of equity.
Black’s blot on the 9pt will have to fend for itself. It can be hit by 10 numbers: 61 52 43 62 53. White’s 22 and 44 are better played by not hitting.
.
Position 2: Black 41-split, White 63-split, Black to play 43
In the second position, White played 63-split (24/18, 13/10). Now White’s offensive threat is somewhat less. He makes his 5pt with 7 rolls (53 51 31 11). With 33, he should not make his 5pt. He should anchor, and make his 3pt, instead. White still makes a point on Black’s head with 55, but his 66 is better used to make an anchor.
If Black makes the anchor, White will have a direct shot at the 9pt. He hits with 12 numbers: any 2, plus the joker 44. That’s 5.5% more than in Position 1. With 53, White should not hit. Making his 5pt is better.
At the rollout below confirms, Black should play offense here. 43-point (9/5 8/5) beats 43-anchor (24/20 23/20) by 0.042.
.
Position 3: Black 41-split, White 51-split, Black to play 43
In Position 3, White played 51-split (24/23 13/8). Offensively, he is not threatening very much. He can make the 5pt with 4 rolls: 33 31 11. The joker 44 plays well for White. He should skip making the 5pt, and make two points inside, while hitting.
If Black leaves his blot on the 9pt, White can hit it with the same 10 rolls he has in Position 1.
Once again, this is a case of offense beating defense. The 3-ply rollout that follows has 43-point (9/5 8/5) beating 43-anchor (24/20 23/20) by 0.016.
.
Position 4: Black 41-split, White 61-point, Black to play 43
In Position 4, White made his bar point, playing 61-point (13/7 8/7). Perhaps this is the easiest of the four positions. White has only 5 numbers that hit on the 9pt: 62 53 44. Meanwhile, White has blocked Black’s direct exit from the 24pt. Black will have to advance his back checkers before they can jump into the outfield. This is the perfect time to anchor.
The rollout favors anchoring by 0.083.
11-02-2012
, 08:20 AM
.
Position 1: Black 41-split, White 21-split, Black to play 43
Position 1: Black 41-split, White 21-split, Black to play 43
Code:
XGID=-aa---E-CA--dDa--c-e---AA-:0:0:1:34:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
Pip count X: 162 O: 164 X-O: 0-0
Cube: 1
X to play 34
1. Rollout¹ 24/20 23/20 eq:+0.2459
Player: 55.50% (G:14.05% B:0.50%)
Opponent: 44.50% (G:8.13% B:0.30%)
Confidence: ±0.0052 (+0.2407..+0.2510) - [100.0%]
Duration: 1 hour 36 minutes
2. Rollout¹ 9/5 8/5 eq:+0.2232 (-0.0227)
Player: 54.77% (G:17.71% B:0.76%)
Opponent: 45.23% (G:11.84% B:0.50%)
Confidence: ±0.0055 (+0.2177..+0.2287) - [0.0%]
Duration: 1 hour 21 minutes
¹ 10368 Games rolled with Variance Reduction.
Dice Seed: 22858044
Moves: 3-ply, cube decisions: XG Roller
Rollout by Taper_Mike
2012-Aug-31
eXtreme Gammon Version: 2.03
41S-21S-43-tm.xgp
41S-21S-43 [@ P23] "<=10
41S-21S-43 [@ P15] "&e