On 4/7/2022 2:31 PM, Axel Reichert wrote:
Did anyone here compare in some more detail the above three approaches:
1. Fill the highest gap
2. Reduce the biggest stack difference
3. Minimize wastage according to some adjusted pip count
What techniques do you use over the board?
I have not studied these heuristics or compared them. Here are some of
the heuristics I use.
1. Playing 6/3 or 4/2 or 2/1 is usually an efficient use of a miss. So
if I have enough checkers on my 6pt then I will tend to play 4/2 rather
than 5/3 (if both the 2pt and 3pt are vacant), reasoning that the gap on
the 3pt is already "covered" by the 6pt. Here's an example.
XGID=-A--BBD------------dbb--a-:1:-1:1:62:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O O | +---+
| | | O O O | | 2 |
| | | O | +---+
| | | O |
| | | |
| |BAR| |
| | | |
| | | X |
| | | X |
| | | X X X |
| | | X X X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 43 O: 43 X-O: 0-0
Cube: 2, O own cube
X to play 62
1. Rollout¹ 6/Off 4/2 eq:+0.176
Player: 63.41% (G:0.00% B:0.00%)
Opponent: 36.59% (G:0.00% B:0.00%)
Confidence: ±0.001 (+0.175..+0.177) - [100.0%]
2. Rollout¹ 6/4 6/Off eq:+0.170 (-0.006)
Player: 63.21% (G:0.00% B:0.00%)
Opponent: 36.79% (G:0.00% B:0.00%)
Confidence: ±0.001 (+0.169..+0.172) - [0.0%]
3. Rollout¹ 6/Off 5/3 eq:+0.169 (-0.007)
Player: 63.15% (G:0.00% B:0.00%)
Opponent: 36.85% (G:0.00% B:0.00%)
Confidence: ±0.001 (+0.168..+0.170) - [0.0%]
¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves and cube decisions: XG Roller++
Search interval: Gigantic
eXtreme Gammon Version: 2.19.207.pre-release
2. When I'm down to 2 checkers, it's best to keep them e = 2.718... pips
apart, or as close to that as you can make them. So checkers on the
5 and 2 are better than checkers on the 4 and 3 or on the 6 and 1.
3. The opponent's position can matter. Most obviously, if my only
chance of winning is to roll doublets then I will maximize my chance of
rolling doublets. Less obviously, if I'm losing then I will fill high
gaps and if I'm way ahead then I will fill low gaps. Example:
XGID=---BBBC------------dbbb---:1:-1:1:62:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O O | +---+
| | | O O O O | | 2 |
| | | O | +---+
| | | O |
| | | |
| |BAR| |
| | | |
| | | |
| | | X |
| | | X X X X |
| | | X X X X |
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 42 O: 48 X-O: 0-0
Cube: 2, O own cube
X to play 62
1. Rollout¹ 6/Off 3/1 eq:+0.549
Player: 79.81% (G:0.00% B:0.00%)
Opponent: 20.19% (G:0.00% B:0.00%)
Confidence: ±0.001 (+0.548..+0.549) - [100.0%]
2. Rollout¹ 6/Off 4/2 eq:+0.545 (-0.003)
Player: 79.65% (G:0.00% B:0.00%)
Opponent: 20.35% (G:0.00% B:0.00%)
Confidence: ±0.001 (+0.544..+0.546) - [0.0%]
¹ 1296 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves and cube decisions: XG Roller+
Search interval: Gigantic
eXtreme Gammon Version: 2.19.207.pre-release
XGID=---BBBC------------abbb---:1:1:1:62:0:0:3:0:10
X:Player 1 O:Player 2
Score is X:0 O:0. Unlimited Game, Jacoby Beaver
+13-14-15-16-17-18------19-20-21-22-23-24-+
| | | O O O O |
| | | O O O |
| | | |
| | | |
| | | |
| |BAR| |
| | | |
| | | |
| | | X | +---+
| | | X X X X | | 2 |
| | | X X X X | +---+
+12-11-10--9--8--7-------6--5--4--3--2--1-+
Pip count X: 42 O: 30 X-O: 0-0
Cube: 2, X own cube
X to play 62
1. Rollout¹ 6/Off 4/2 eq:-0.545
Player: 20.68% (G:0.00% B:0.00%)
Opponent: 79.32% (G:0.00% B:0.00%)
Confidence: ±0.000 (-0.546..-0.545) - [99.9%]
2. Rollout¹ 6/4 6/Off eq:-0.546 (-0.001)
Player: 20.58% (G:0.00% B:0.00%)
Opponent: 79.42% (G:0.00% B:0.00%)
Confidence: ±0.000 (-0.547..-0.546) - [0.1%]
3. Rollout¹ 6/Off 3/1 eq:-0.549 (-0.004)
Player: 20.70% (G:0.00% B:0.00%)
Opponent: 79.30% (G:0.00% B:0.00%)
Confidence: ±0.000 (-0.550..-0.549) - [0.0%]
¹ 5184 Games rolled with Variance Reduction.
Dice Seed: 271828
Moves and cube decisions: XG Roller+
Search interval: Gigantic
eXtreme Gammon Version: 2.19.207.pre-release
---
Tim Chow
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