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5 Positions from Superbackgame
Posted By: Taper_Mike In Response To: 5 Positions from Superbackgame (Stick)
Date: Monday, 18 March 2013, at 7:52 a.m.
Thanks for posting such an interesting set. Number 1
White is Player 1
score: 0
pip: 220Unlimited Game
Jacoby Beaverpip: 132
score: 0
Blue is Player 2XGID=--bbb-EBCA--dC--Ac-b------:0:0:1:62:0:0:3:0:10 Blue to play 62 I don’t mind too much getting hit, but not from White’s spares on the midpoint. So the 6 goes down to the 10pt. Then, at least over the board, I would lift the blot on the 9pt with the 2, D (Down) = 16/10 9/7. The QF play, of course, is to leave it, D (Down) = 16/10 13/11.
Number 2
White is XG Roller+
score: 0
pip: 126Unlimited Game
Jacoby Beaverpip: 220
score: 0
Blue is Player 1XGID=------B-C---cDa-acbdaBBB--:0:0:1:51:0:0:3:0:10 Blue to play 51 It is way too early to hit. After hitting, it would be nearly impossible to contain the opponent’s checkers, and the three-anchor backgame might forever be reduced to two. Ideally, the hit(s) should come after the opponent has been forced to dismantle his offense.
Play D (Down) = 13/7.
Number 3
White is XG Roller+
score: 0
pip: 60Unlimited Game
Jacoby Beaverpip: 152
score: 0
Blue is Player 1XGID=--BBABB--A-------Abeb-BBf-:0:0:1:00:0:0:3:0:10 Blue on roll, cube action? I believe it was Barclay Cooke, in one of his texts, who has a club mate saying, “Missing a double shot is the easiest thing in the world.” With Blue’s board still incomplete, I would take in a flash. Don’t get me wrong. It’s not that I want to be doubled. This just looks like an easy take. As Blue, I would not double here.
Number 4
White is Player 2
score: 0
pip: 15Unlimited Game
Jacoby Beaverpip: 130
score: 0
Blue is Player 1XGID=--BBBBC---------A--a-aABe-:1:1:1:00:0:0:3:0:10 Blue on roll, cube action? Now, this is more like it. Usually it is better to hit before cubing, but there are only 4 rolls that miss this quadruple shot. Doubling deserves serious consideration.
Blue’s rolls look like this:
- (4/36) Whiff: 66 65 55
- (7/36) Hit on 19pt from 23pt: 64 54 44 43 (leaving a double shot at the second checker)
- (5/36) Hit on 19pt from 22pt: 63 53 33
- (4/36) Hit on 21pt from 23pt: 62 52 (leaving a triple shot at the second checker)
- (4/36) Hit on 21pt from 22pt: 61 51 (leaving a double shot at the second checker)
- (2/36) Hit on 21pt + split: 31 (leaving a triple shot at the second checker)
- (10/36) Hit twice: 42 41 32 22 21 11
In summary:
- (4/36) Hit 0 checkers
- (22/36) Hit 1 checker
- (10/36) Hit 2 checkers
After two checkers are hit, if they are closed out, White’s winning chances with 8 checkers off fall to about 9%. For simplicity, let’s assume that whenever Blue hits both checkers on the first try, he always contains them.
When only one checker is hit, White will have only 2 or 3 immediate rolls in 36 that enter and safety the second checker. That’s the bad news. The good news is that given a chance to shoot at the second checker, Blue might not hit it on his first try. Of the 11 rolls where White enters immediately, let’s guess Blue can eventually pick up both of White’s checkers after at least 8 of them. That means we are guessing Blue will hit and contain both checkers in about 19 or 20 of the 22 games where Blue hits only one checker initially. To be cautious, and allow for other various ways that White might rebound, let’s round that down to 18.
In the other 4 games, even when White’s single checker is closed out, his winning chances are between 48% and 52% depending whether Blue can get an optimal arrangement of spares.
Suppose Blue misses the hit on his first try. Then he will get a second chance 16 times in 36. The other 20 times he will likely face a gammon loss. Here is the breakdown of White’s rolls (after a Blue miss). White will safety at least one of his checkers in all of them.
First, the 16 shot-leaving numbers:
- (6/36) 62, 52, and 42, played 6/off, leave 20 shots.
- (6/36) 61, 51, and 43 hit loose on the 3pt, leaving return hits with any 3 (from the bar), plus 61, 51, 41, and 21. That’s 19 shots.
- (2/36) 41 is best played bearing off a checker and leaving 21 shots at a blot on the 5pt.
- (2/36) 32 played 6/1 leaves 20 shots. Played 6/3*/1 gives White return hits with any 4 (from the bar), plus 31, 62, 52, 32, and 22. That would be 21 shots.
The other 20 rolls all play safely:
- (14/36) 65 64 63 54 53 66 55 44 33 all run past Blue.
- (3/36) 31 and 11 points on head on 3pt.
- (3/36) 22 and 21 make the 4pt.
Of the 4 games where Blue misses his first shot, he will hit on his second try about (16/36)*(20/36) or 25% of the time. After that, if we grant him the closeout, he will win only half of those. To be generous, let’s guess Blue will win 1/2 game of the 4, lose 1/2 single game, and lose 3 gammons.
Totalling our cross-section of 36 games:
Blue hits and contains both checkers in 28 games. Let’s say Blue wins 25 of those, losing only a single game in the other 3.
Of the other 4 games where Blue hits on his first try, he should be able to contain White in at least 3 of them. With a close out, he will win half of those, or 1.5 games, losing a single game in another 1.5. In the fourth, lets say White somehow wins a single game only. In reality, White will sometimes win a gammon, but those wins will be offset by the fact that White will probably not escape at that high rate we have assumed.
- Blue wins single game: 0.5 + 25 + 1.5 = 27
- Blue loses single game: 0.5 + 3 + 2.5 = 6
- Blue loses a gammon: 3
If all my guesses are accurate ;-) then this position is Double / Take.
Number 5
White is Player 1
score: 0
pip: 161Unlimited Game
Jacoby Beaverpip: 82
score: 0
Blue is XG Roller+XGID=--BBABB-------A---cefABBa-:0:0:-1:00:0:0:3:0:10 Blue on roll, cube action? I would not double this. Blue has awkward 3s, to say the least. Even the POH numbers like 31 and 32 leave White shooting at the blot on the 1pt.
Were there no gap between White’s anchors and Blue’s forces, then I would double.
Mike
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