Game #2

Open Division Final
San Mateo, California
17 November 1996
11 Point Match

Kevin Mansfield (X) vs. Nick Ballard (O)
Score: 0 - 0

Analysis by Steve Clark

This is the first game of the Open Division finals for November.

Kevin Mansfield, known variously as lucky and as UNLUCKY in FIBSdom, demonstrated his backgammon Skill by playing through to the final round. Nick Ballard, known usually as Nack in all manner of gaming venues, demonstrated his Nackedness. We thank both participants for sharing this exciting sample game from their match with us.

Play 1a

+-------------+---+-------------+ | O X | | X O | | O X | | X O | | X | | X O | | X | | O | 167 | X | | O | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | O | | X | | O | | X | 167 | O | | O X | | X O | | O X | | X O | | O X | +-------------+---+-------------+

X to play 52 Candidate Plays Equities 13/8 24/22 +0.005 13/8 13/11 +0.000

SC:	This rollout result surprised everyone when it first appeared. Before rollouts, 13/8 24/22 was not considered a candidate move by any expert. Now it is probably slightly preferred by players at all levels. Which play you choose is really a matter of taste.

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	X	O
1.	52: 13/8 13/11
Play 1b	+-------------+---+-------------+ | O X | | X X O | | O X | | X O | | X | | X O | | X | | X O | 160 | X | | O | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | O | | | | O | | | 167 | O | | O X | | X O | | O X | | X O | | O X | +-------------+---+-------------+			O to play 52 Candidate Plays Equities 13/8 13/11 -0.092 13/8 24/22 -0.111 13/8 6/4 -0.122 13/6 -0.163 8/3 13/11 -0.183

SC:

If your opponent rolls a 52 or 54 on the opening move, it is generally best to imitate his method on play. If he splits from the 24 point, you should split from the 24 in reply. If he brings builders from the 13 point, you should bring builders from the 13 point in reply. However, if he slots, do not slot in reply.

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	X	O
1.	...	52: 13/8 13/11
2.	31: 8/5 6/5	53: 8/3 6/3
3.	61: 13/7 8/7	41: 11/7 8/7
Play 4a	+-------------+---+-------------+ | O X X | | X X X O | | O X X | | X X O | | X | | O | | X | | | 149 | | | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | | | | O | | | 147 | O | | | | X O O | | O O X | | X O O | | O O X | +-------------+---+-------------+			X to play 53 Candidate Plays Equities 24/16 +0.229 8/3 6/3 +0.220 11/6 24/21 +0.192 13/8 13/10 +0.167

SC:

Normally playing 24/21 along with the 5 played elsewhere, such as 13/8, is to be preferred. However, here the 5 part of that play is awkward, so other moves come to the forefront. 8/3 6/3 makes the 3 point, which is valuable but leaves the back checkers hemmed in and leaves a blot on the 8 point. 24/16 starts to escape but not particularly effectively. The choice is close.

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	X	O
4.	53: 24/16	44: 13/9*/5(2)
Play 5a	+-------------+---+-------------+ | O X X | | X X X O | | O X X | | X X | | X | | | | X | | | 150 | | | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | X | | | O | | | 131 | O | | | | O O O | | O O X | | X O O O | | O O X | +-------------+---+-------------+			X to play 11 Candidate Plays Equities Bar/23 24/23 13/12* +0.326 Bar/24 13/12* 11/10 6/5 +0.278 Bar/24 13/12* 11/9 +0.229 Bar/24 13/12*/11 6/5 +0.224 Bar/24 13/12*(2) 6/5 +0.213 Bar/24 13/12*/10 +0.192 Bar/23 13/12* 6/5 +0.180 Bar/23 13/12*/11 +0.168 Bar/23 13/12*(2) +0.136 Bar/23 13/12* 11/10 +0.136

SC:

Bar/23 13/12 are clear with 3 parts of the move. The choice is on the last ace, with 24/23 being the clear winner. This result might seem surprising, but it has the benefit of denying O any hits with his awkward numbers. Instead O often will have the break his 7 or 8 point soon, without being able to attack. If O were more likely to retain his partial prime, then splitting would be much more desirable.

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	X	O
5.	11: Bar/23 13/12* 6/5
Play 5b	+-------------+---+-------------+ | O X X | | X X X X | | O X X | | X X | | X X | | | | | | | 146 | | O | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | | | | O | | | 143 | O | | | | O O O | | O O | | X X O O O | | O O X | +-------------+---+-------------+			O to play 33 Candidate Plays Equities Bar/22 24/21(2) 6/3 +0.155 Bar/22 24/21 7/4(2) +0.007

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	X	O
5.	...	33: Bar/22 24/21(2) 6/3
Play 6a	+-------------+---+-------------+ | O O X X | | X X X X | | O X X | | X X | | X X | | | | | | | 146 | | | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | | | | | | | 131 | O O | | | | O O O | | O O | | X X O O O | | O O X | +-------------+---+-------------+			X to play 11 Candidate Plays Equities 24/23 12/10 11/10 -0.044 24/23 13/11 12/11 -0.143

SC:	Again making the 23 point is the winner. Putting blockers on the 10 point also must be right.

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	X	O
6.	24/23 12/10 11/10
Play 6b	+-------------+---+-------------+ | O O X X | | X X X | | O X X | | X X X | | X X | | | | | | | 142 | | | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | | | | | | | 131 | O O | | | | X O O O | | O O | | X O O O | | O O X | +-------------+---+-------------+			O to play 41 Candidate Plays Equities 6/1 -0.116 7/3 7/6 -0.191 8/4 8/7 -0.212

SC:	This rollout demonstrates that there is no real benefit to moving from the 7 point. If O gives up the 7 point here, X just has more flexibility and O has put his checkers on the wrong spots.

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	X	O
6.	...	41: 6/1
Play 7a	+-------------+---+-------------+ | O O X X | | X X X | | O X X | | X X X | | X X | | | | | | | 142 | | | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | | | | | | | 126 | O | | | | X O O O | | O O | | O X O O O | | O O X | +-------------+---+-------------+			X to play 61 Candidate Plays Equities 13/6 +0.040 13/7 6/5 +0.010 10/3* -0.097

SC:	Put the spares on the 6 point. Woolsey's 4th law.

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	X	O
7.	61: 13/6
Play 7b	+-------------+---+-------------+ | O O X X | | X X X | | O X X | | X X X | | X X | | | | X | | | 135 | | | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | | | | | | | 126 | O | | | | X O O O | | O O | | O X O O O | | O O | +-------------+---+-------------+			O to play 42 Candidate Plays Equities 7/3 7/5 -0.241 7/1 -0.289 8/4 8/6 -0.327

SC:	Making the ace point would be nice, but the blot remaining on the 7 point would be a very attractive victim.

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	X	O
7.	...	42: 7/3 7/5
Play 8a	+-------------+---+-------------+ | O O X X | | X X X | | O X X | | X X X | | X X | | | | X | | | 135 | | | | | | | | +---+ | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | +---+ | | | | | O | | | 120 | O O | | | | X O O O | | O | | O X O O O | | O | +-------------+---+-------------+			X to play. Double or roll? Equity (center cube) X 67.5% G 2.4% BG 0.2% O 32.5% G 2.0% BG 0.1% Equity (X): +0.354 Equity (O owns 2 cube) X 50.3% G 13.2% BG 0.6% O 49.7% G 2.7% BG 0.1% Equity (O): -0.116 Equity (cubeless) X 59.8% G 14.3% BG 0.7% O 40.2% G 10.8% BG 0.4% Equity (X): +0.235

SC:	This is not really very close to a double. X still has two checkers back which might have difficultly escaping. O is anchored on the 4 point, so his racing lead could always come into play. X might not have a double even if he escaped one of the back checkers.
JF:	I would not have doubled (level 7 evaluation).

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	X	O
8.	Double -> 2	Accept
Play 9a	+-------------+---+-------------+ | O O X X | | X X X | | O X X | | X X X | | X X | | | | X | | | 135 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O | | | 120 | O O | | | | X O O O | | O | +---+ | O X O O O | | O | | 2 | +-------------+---+-------------+ +---+			X to play 42 Candidate Plays Equities 7/3* 5/3 +0.204 6/2 5/3* +0.178 10/6 10/8 +0.125 10/6 5/3* +0.100 6/2 23/21 +0.071

SC:	6/2 23/21, the play made at the table, gives O too many options. O will be happy to attack with the right roll or escape if that possibility comes up. In the meantime, the checker on the 2 point is a real weakness. Hitting gives up the prime, but O's reply hits are not that strong.

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	X	O
9.	42: 6/2 23/21	63: 22/13
Play 10a	+-------------+---+-------------+ | X O X X | | X X X O | | O X X | | X X X | | X X | | | | | | | 129 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O | | | 111 | O O | | | | O O O | | O | +---+ | O X O X O O | | O | | 2 | +-------------+---+-------------+ +---+			X to play 21 Candidate Plays Equities 23/21 2/1 +0.111 23/21 6/5 +0.097

SC:	Although the equities are close, the correct play is clear.

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	X	O
10.	21: 23/21 2/1
Play 10b	+-------------+---+-------------+ | X O X X | | X X X O | | O X X | | X X X | | X X | | | | | | | 126 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O | | | 111 | O O | | | | O X O O | | O | +---+ | O O X O O | | O | | 2 | +-------------+---+-------------+ +---+			O to play 62 Candidate Plays Equities 13/5 -0.163 13/7 3/1 -0.168 8/2 8/6 -0.198 8/2 3/1 -0.269

SC:

The question comes up over and over again of how much risk you should take in order to make a stronger board. In this example, the board-building play is equal to the safe play. Some factors in favor of taking the risk are: The extra checker on the 7 point will provide flexibility next roll. Playing safe to the 5 point is quite awkward. It might not be convenient to make the ace point later. The ace point is clearly valuable here, since the extra checkers on the 3 point are already past X's anchor. If O is hit, he probably will have a shot at the blot on X's 1 point. O will leave only 11 hitting rolls. Factors in favor of playing safe are: A hit here will change the race. A hit would put the blot behind a 5-out-of-6 prime. In summary, the hit is a fairly strong incentive to play safely, but moving to the 5 point leaves an undesirable follow-up. The choice is close.

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	X	O
10.	...	62: 13/7 3/1
11.	64: 7/1 7/3
Play 11b	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X | | | | | | | 116 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | | | | 103 | O O | | | | O O X O O | | O | +---+ | O O X O O | | O O | | 2 | +-------------+---+-------------+ +---+			O to play 42 Candidate Plays Equities 7/1 -0.154 7/3 5/3 -0.243 7/3 8/6 -0.248

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	X	O
11.	...	42: 7/1
Play 12a	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X | | | | | | | 116 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | | | | 97 | O O O | | | | O O X O O | | O | +---+ | O O X O O | | O | | 2 | +-------------+---+-------------+ +---+			X to play 65 Candidate Plays Equities 21/15 21/16 +0.238 8/2 8/3 +0.192

SC:	When doing rollouts one is often faced with choices where the results are close and the various moves seem much alike. Is there a clear winning play here? Got me.

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	X	O
12.	65: 21/15 21/16
Play 12b	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X | | | | | | | 105 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | | | | 97 | O O O | | | | O O O O | | O | +---+ | O O O O | | O X X | | 2 | +-------------+---+-------------+ +---+			O to play 32 Candidate Plays Equities 5/2 8/6 -0.336 5/2 3/1 -0.350 8/5 8/6 -0.358 8/5 3/1 -0.362 8/3 -0.369

SC:

The equities may be close in rollouts of this type of position, but the priorities are clear. You should slot the holes in your board and distribute your other checkers. This will allow you to build a better board in future rolls, and having all your points slotted will help you when the position becomes a race. The danger of having extra blots when you hit a fly shot is something you just have to live with. More likely, your hitting roll will come later, when you will be grateful if you have improved your board.

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	X	O
12.	...	32: 5/2 8/6
Play 13a	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X | | | | | | | 105 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | | | | 92 | O O O | | | | O O O O | | | +---+ | O O O O O | | O X X | | 2 | +-------------+---+-------------+ +---+			X to play 64 Candidate Plays Equities 15/5 +0.333 16/10 6/2 +0.327 16/10 15/11 +0.314 16/6 +0.314 16/10 5/1 +0.239

SC:	This result will surprise a lot a players. It demonstrates the importance of the race in such positions. When you move 5/1, you do significant damage to your chances in the bearoff. Here that factor more than offsets the problems of an extra blot and the poorer distribution on the 5 and 6 points.

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	X	O
13.	64: 15/5
Play 13b	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X | | | | X | | | 95 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | | | | 92 | O O O | | | | O O O O | | | +---+ | O O O O O | | O X | | 2 | +-------------+---+-------------+ +---+			O to play 63 Candidate Plays Equities 8/2 21/18 -0.375 8/2 6/3 -0.395 8/2 5/2 -0.443

SC:	A five point board, a racing lead, and a X blot on the 3 point encourage O to run. Even so, X is a strong favorite. It is difficult to make this kind of split at the table.

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	X	O
13.	...	63: 8/2 6/3
Play 14a	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X | | | | X | | | 95 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O | | | 83 | O O | | | | O O O O O | | | +---+ | O O O O O | | X | | 2 | +-------------+---+-------------+ +---+			X to play 54 Candidate Plays Equities 16/11 6/2 +0.266 16/11 5/1 +0.245 6/1 16/12 +0.235 6/1 5/1 +0.199

SC:	This is a position worth looking at. Each of the three best candidate plays offers a different degree of risk, yet is about equally good. Look at the factors favoring each and against each.

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	X	O
14.	54: 16/11 5/1
Play 14b	+-------------+---+-------------+ | X X O X X | | X X X | | X O X X | | X X | | X X X | | | | | | | 86 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O | | | 83 | O O | | | | O O O O O | | | +---+ | O O O O O | | | | 2 | +-------------+---+-------------+ +---+			O to play 31 Candidate Plays Equities 6/2 -0.445 6/3 6/5 -0.454 5/1 -0.461 5/2 5/4 -0.461 5/2 3/2 -0.466

SC:	The alternatives are about equal. Actually I would play 6/3 6/5, despite the rollout results.

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	X	O
14.	...	31: 6/2
Play 15a	+-------------+---+-------------+ | X X O X X | | X X X | | X O X X | | X X | | X X X | | | | | | | 86 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O | | | 79 | O O O | | | | O O O O | | | +---+ | O O O O O | | | | 2 | +-------------+---+-------------+ +---+			X to play 42 Candidate Plays Equities 11/7 5/3 +0.409 11/5 +0.406 6/2 5/3 +0.403 6/2 3/1 +0.295 5/1 5/3 +0.106

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	X	O
15.	42: 11/5
Play 15b	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X X | | | | X | | | 80 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O | | | 79 | O O O | | | | O O O O | | | +---+ | O O O O O | | | | 2 | +-------------+---+-------------+ +---+			O to play 32 Candidate Plays Equities 6/1 -0.443 5/2 3/1 -0.511

SC:	6/1 must be right. It saves as many home board points as possible.

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	X	O
15.	...	32: 6/1
Play 16a	+-------------+---+-------------+ | X X O X X | | X X | | X O X X | | X X | | X X X | | | | X | | | 80 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O O | | | 74 | O O O | | | | O O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			X to play 31 Candidate Plays Equities 5/2 3/2 +0.490 5/1 +0.395

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	X	O
16.	31: 5/2 3/2
Play 16b	+-------------+---+-------------+ | X X O X X | | X X | | X X O X X | | X X | | X X X | | | | | | | 76 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | | | | | O O | | | 74 | O O O | | | | O O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			O to play 21 Candidate Plays Equities 3/1 2/1 -0.476 3/1 3/2 -0.482

SC:	Random equity difference.

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	X	O
16.	...	21: 3/1 2/1
Play 17a	+-------------+---+-------------+ | X X O X X | | X X | | X X O X X | | X X | | X X X | | | | | | | 76 | | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 | | | | O | | | 71 | O O | | | | O O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			X to play 22 Candidate Plays Equities 10/6(2) +0.487 5/1 5/3(2) +0.471 10/6 10/8 5/3 +0.469 8/6(2) 5/1 +0.425

SC:	You can't start taking your checkers off until you get them all in.

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	X	O
17.	22: 10/6(2)
Play 17b	+-------------+---+-------------+ | X X O X X | | X | | X X O X X | | X | | X X X | | | | X | | | 68 | X | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 | | | | O | | | 71 | O O | | | | O O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			O to play 52 Candidate Plays Equities 21/14 -0.560 21/16 3/1 -0.601

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	X	O
17.	...	52: 21/14
18.	31: 5/4*/1	21: Cannot move
19.	62: 8/2 8/6	11: Cannot move
20.	64: 6/Off 6/2	61: Cannot move
Play 21a	+-------------+---+-------------+ | X X X X | | O | | X X X X | | | | X X X | | | | X X X | | | 46 | | O | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 | | | | O | | | 68 | O O | | | | O O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			X to play 41 Candidate Plays Equities 6/2 1/Off +0.871 6/2 6/5 +0.852 6/1 +0.825

SC:	This result surprises me. The general principle to follow in these positions is to have an even number of checkers on the highest point. Here taking an extra checker off and the overall awkwardness in any event make 6/2 1/Off the winner.

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	X	O
21.	41: 6/2 6/5
Play 21b	+-------------+---+-------------+ | X X X X | | O | | X X X X | | | | X X X | | | | X X | | | 41 | X | O | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 | | | | O | | | 68 | O O | | | | O O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			O to play 64 Candidate Plays Equities Bar/21 14/8 -0.858 Bar/15 -0.932

SC:	O does not have much chance to win here. If he runs, he will have even less.

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	X	O
21.	...	64: Bar/21 14/8
Play 22a	+-------------+---+-------------+ | X X O X X | | | | X X X X | | | | X X X | | | | X X | | | 41 | X | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 | | | | O | | | 58 | O O | | | | O O O O | | | +---+ | O O O O | | O | | 2 | +-------------+---+-------------+ +---+			X to play 21 Candidate Plays Equities 2/Off 1/Off +0.903 5/3 1/Off +0.877 2/Off 2/1 +0.847 5/4*/2 +0.795 5/2 +0.771

SC:	If white rolls big doubles, X could be very sorry for not taking two checkers off. The difference, however, is small.

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	X	O
22.	21: 5/3 1/Off
Play 22b	+-------------+---+-------------+ | X X X O X X | | | | X X X X | | | | X X | | | | X | | | 38 | X | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 | | | | O | | | 58 | O O | | | | O O O O | | | +---+ | O O O O | | O | | 2 | +-------------+---+-------------+ +---+			O to play 22 Candidate Plays Equities 8/4 5/1 -0.906 8/2 3/1 -0.910 8/4 5/3(2) -0.911 8/4 3/1(2) -0.918 8/6 5/1 3/1 -0.922

SC:	Note that the race-oriented play here is a slight winner over keeping the board together. This result illustrates again the importance of the race in these late-game positions.

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	X	O
22.	...	22: 8/4 5/3(2)
Play 23a	+-------------+---+-------------+ | X X X O X X | | | | X X X X | | | | X X | | | | X | | | 38 | X | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 O | | | | O O | | | 50 | O O | | | | O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			X to play 32 Candidate Plays Equities 3/Off 2/Off +0.936 5/2 5/3 +0.829

SC:	X has a phantom at the table. I do not see any follow-up which makes 5/2 5/3 the winner.

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	X	O
23.	32: 5/2 5/3
Play 23b	+-------------+---+-------------+ | X X X O X | | | | X X X X | | | | X X | | | | X | | | 33 | 6 | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 6 O | | | | O O | | | 50 | O O | | | | O O O | | | +---+ | O O O O | | | | 2 | +-------------+---+-------------+ +---+			O to play 31 Candidate Plays Equities 4/1 3/2 -0.873 4/1 21/20 -0.901 4/1 2/1 -0.916 21/17 -0.929 21/18 3/2 -0.932

SC:	O sticks around for the last-ditch shot.

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	X	O
23.	...	31: 4/1 3/2
Play 24a	+-------------+---+-------------+ | X X X O X | | | | X X X X | | | | X X | | | | X | | | 33 | 6 | | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 7 | | | | O O | | | 46 | O O O | | | | O O O | | | +---+ | O O O | | | | 2 | +-------------+---+-------------+ +---+			X to play 42 Candidate Plays Equities 6/2 6/4* +0.678 6/2/Off +0.669 6/4*/Off +0.657

SC:

An interesting problem at the end of the game. 6/2/Off takes a checker off but leaves 12 shots instead of 11. 6/2 6/4* leaves the minimum number of shots, gives O an extra crossover, and has the hope of keeping O on the bar, but gets no checkers off. 6/4*/Off hits and gets a checker off, but leaves the most return shots by far. Here 6/2 6/4* provides the most safety and the hit helps in the race, so it is the winner.

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	X	O
24.	42: 6/2 6/4*
Play 24b	+-------------+---+-------------+ | X X X X | | | | X X X | | | | X X | | | | X | | | 27 | 7 | O | | | | | | | 1 2 3 4 5 6 |BAR| 7 8 9 0 1 2 | | | | | | 7 | | | | O O | | | 50 | O O O | | | | O O O | | | +---+ | O O O | | | | 2 | +-------------+---+-------------+ +---+			O to play 62

O got a shot, but missed. X won the race to lead 2-0.

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The game was recorded on tape by Richard McIntosh, and transcribed by Steve Clark.

Rollouts were made by Richard McIntosh, using JellyFish Analyzer 2.02. Rollout results show equities for the player on move. Candidate plays were better than or within 0.100 equity of the actual plays, evaluated at level 7.

Parameter values for rollouts on moves were:

• level 5
• 7776 games (36x216)
• horizon 7
• seed 6788

Standard deviations of equity estimates were between 0.002 and 0.009.

Parameter values for rollouts on cube decisions were:

• level 5
• 23328 games (36x648)
• full game
• seed 6788
• settlement limit 0.570

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