I sometimes joke that in positions like the one below, O is playing
a "0-1 backgame."


XGID=bcBBCCB-C--------b-bbbb---:1:-1:1:33:0:0:0:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| O | | O O O O | +---+
| O | | O O O O | | 2 |
| | | | +---+
| | | |
| | | |
| |BAR| |
| | O | |
| | O | |
| X | | X X O |
| X | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 73 O: 174 X-O: 0-0
Cube: 2, O own cube
X to play 33

---
Tim Chow

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

XGID=bcBBCCB-C--------b-bbbb---:1:-1:1:33:0:0:0:0:10

X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| O | | O O O O | +---+
| O | | O O O O | | 2 |
| | | | +---+
| | | |
| | | |
| |BAR| |
| | O | |
| | O | |
| X | | X X O |
| X | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 73 O: 174 X-O: 0-0
Cube: 2, O own cube
X to play 33

Despite having seen this type of "pre-clearing" play numerous times
before, I still tend to miss it OTB.

1. Rollout¹ 8/5(2) 6/3(2) eq:+1.240
Player: 79.12% (G:60.24% B:14.57%)
Opponent: 20.88% (G:0.01% B:0.00%)
Confidence: ±0.009 (+1.231..+1.249) - [100.0%]

2. Rollout¹ 8/2 6/3(2) eq:+1.141 (-0.099)
Player: 76.72% (G:58.53% B:13.18%)
Opponent: 23.28% (G:0.27% B:0.01%)
Confidence: ±0.010 (+1.131..+1.150) - [0.0%]

3. Rollout¹ 8/5(2) 8/2 eq:+1.104 (-0.136)
Player: 74.60% (G:57.01% B:15.60%)
Opponent: 25.40% (G:0.00% B:0.00%)
Confidence: ±0.010 (+1.094..+1.114) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.207.pre-release

---
Tim Chow

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

The subject line is a joke that my playing group enjoys.

XGID=bcBCBCCB---------bccb-----:1:-1:1:44:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| O O | | O O | +---+
| O O | | O O | | 2 |
| O | | O | +---+
| | | |
| | | |
| |BAR| |
| | O | |
| | O | |
| | | X X X O |
| X | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 68 O: 187 X-O: 0-0
Cube: 2, O own cube
X to play 44

---
Tim Chow

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 9/14/2023 8:52 AM, Timothy Chow wrote:

The subject line is a joke that my playing group enjoys.

Many people claim that a 1-5 backgame structure is the weakest, but the
0-1 structure seems to be worse.

XGID=bcBCBCCB---------bccb-----:1:-1:1:44:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
 +13-14-15-16-17-18------19-20-21-22-23-24-+
 |             O  O |   | O  O             | +---+
 |             O  O |   | O  O             | | 2 |
 |                O |   | O                | +---+
 |                  |   |                  |
 |                  |   |                  |
 |                  |BAR|                  |
 |                  | O |                  |
 |                  | O |                  |
 |                  |   | X  X     X     O |
 |                X |   | X  X  X  X  X  O |
 |                X |   | X  X  X  X  X  O |
 +12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count  X: 68  O: 187 X-O: 0-0
Cube: 2, O own cube
X to play 44

If the race were closer and O stood more of a chance of running off the
gammon I'd look seriously at taking two off now. But I don't think it's
worth risking leaving a gap for a marginal increase (assuming it
actually is an increase) in gammons.

So, I'll clear the 6 and play 7/3. It exposes no shots and leaves X even
ended. 7/3 6/2(3)


--
Ah....Clem
The future is fun, the future is fair.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

XGID=bcBCBCCB---------bccb-----:1:-1:1:44:0:0:0:0:10

Score is X:0 O:0. Unlimited Game
+13-14-15-16-17-18------19-20-21-22-23-24-+
| O O | | O O | +---+
| O O | | O O | | 2 |
| O | | O | +---+
| | | |
| | | |
| |BAR| |
| | O | |
| | O | |
| | | X X X O |
| X | | X X X X X O |
| X | | X X X X X O |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 68 O: 187 X-O: 0-0
Cube: 2, O own cube
X to play 44

O has enough checkers back that backgammons are relevant. The
aggressive bearoff play of 7/3(2) 4/off(2) does win slightly more
backgammons. However, as you might expect, that interior gap comes
with a significantly higher risk of blotting later. Clearing the
6pt with 7/3 6/2(3) does give O a 66 joker but is otherwise a safer
play.

Another thing to be aware of is that often, in the endgame, the
more aggressive bearoff play wins more gammons. But here, X's
lead in the pip count is so huge that winning a gammon is not a
matter of winning the gammon race. As long as X is not hit, the
gammon is pretty much in the bag. So the safer play will win
more games *and* gammons. To justify a risk requires a *lot* of
extra backgammon wins, which just aren't available here.

1. Rollout¹ 7/3 6/2(3) eq:+1.124
Player: 75.66% (G:60.55% B:12.10%)
Opponent: 24.34% (G:0.26% B:0.01%)
Confidence: ±0.010 (+1.113..+1.134) - [100.0%]

2. Rollout¹ 7/3(2) 4/Off(2) eq:+0.995 (-0.129)
Player: 71.39% (G:54.40% B:15.58%)
Opponent: 28.61% (G:0.00% B:0.00%)
Confidence: ±0.014 (+0.981..+1.009) - [0.0%]

¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves: 3-ply, cube decisions: XG Roller

eXtreme Gammon Version: 2.19.211.pre-release

---
Tim Chow

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)