I recently mentioned that bots sometimes do funny things during an "easy" bearin against a holding game. Here is some concrete data to back up that assertion.
In the position below, White is XG 3-ply version 1. The first thing to note is that virtually no human would get into a situation like this in the first place, with four blots flooding the home board. Adopting a properly worshipful attitude towards the bot, we might wonder if it knows something that we don't?
Well, the next observation is that XG 3-ply's recommendation for my move in this position is 7/2 7/1, which XGR+ labels a whopper.
          
 
         
 | | White is Player 2
score: 0
pip: 112 | Money session
Jacoby Beaver | pip: 107
score: 0
Blue is Player 1 |
|
| XGID=--ABBBBBA--Ab--bbbBcaaaa--:1:-1:1:65:0:0:3:0:10 |
| Blue to play 65 |
| 1. | XG Roller+ | 18/7 | eq: +0.041 |
| Player:
Opponent: | 58.22% (G:3.82% B:0.12%)
41.78% (G:1.51% B:0.03%) | |
|
| 2. | XG Roller+ | 18/13 8/2 | eq: +0.026 (-0.015) |
| Player:
Opponent: | 57.75% (G:3.66% B:0.12%)
42.25% (G:2.07% B:0.05%) | |
|
| 3. | XG Roller+ | 18/13 11/5 | eq: +0.014 (-0.027) |
| Player:
Opponent: | 57.19% (G:3.84% B:0.14%)
42.81% (G:2.47% B:0.05%) | |
|
| 4. | XG Roller+ | 11/6 8/2 | eq: -0.065 (-0.105) |
| Player:
Opponent: | 54.08% (G:2.91% B:0.06%)
45.92% (G:1.93% B:0.05%) | |
|
| 5. | XG Roller+ | 8/2 7/2 | eq: -0.076 (-0.116) |
| Player:
Opponent: | 53.80% (G:2.69% B:0.05%)
46.20% (G:2.06% B:0.05%) | |
|
| 6. | XG Roller+ | 7/2 7/1 | eq: -0.076 (-0.116) |
| Player:
Opponent: | 53.78% (G:2.73% B:0.06%)
46.22% (G:2.13% B:0.05%) | |
|
eXtreme Gammon Version: 1.21
Let's say we go ahead and follow XG 3-ply's recommendation to see what happens next. We might be faced with the decision below on the next turn, when XG 3-ply recommends 11/7 6/1.
All this shows why I'm not sure I trust a 3-ply rollout of such an "easy" position. I'd be curious to find out to what extent this weakness has been addressed in XG version 2. Does XG 3-ply version 2 still flood its board with gratuitous blots in these sorts of positions?
| | White is Player 2
score: 0
pip: 103 | Money session
Jacoby Beaver | pip: 96
score: 0
Blue is Player 1 |
|
| XGID=-ABBBBB-A--Ab--bb-Bcbaab--:1:-1:1:54:0:0:3:0:10 |
| Blue to play 54 |
| 1. | XG Roller+ | 18/14 18/13 | eq: -0.001 |
| Player:
Opponent: | 54.63% (G:9.03% B:0.91%)
45.37% (G:7.10% B:0.29%) | |
|
| 2. | XG Roller+ | 11/7 6/1 | eq: -0.122 (-0.121) |
| Player:
Opponent: | 51.51% (G:3.72% B:0.06%)
48.49% (G:2.71% B:0.08%) | |
|
eXtreme Gammon Version: 1.21