Here's a pair of positions from a wacko double-snake 15x2 checkers back game -- not a typical backgame -- that somebody posted to r.g.bg. Check out the 2-ply and 3-ply evaluations. Gnubg hasn't a clue in this far-out not typical (thought I should repeat that) position. First, Blue on roll:
DMP.
Move number 114: Blue to play 55
| yeti_yew | 293 |
|---|---|
| |
| PersianLord | 325 |
Position ID: QBjAbTsAANy2Ww Match ID: cIk2AAAAAAAA | |
0.988 0.883 0.055 - 0.012 0.005 0.002
2-ply cubeful prune [world class]
9. Cubeful 2-ply bar/15 23/18*/13 Eq.: +0.940 ( -0.035)
0.970 0.773 0.055 - 0.030 0.010 0.003
2-ply cubeful prune [world class]
1. Cubeful 3-ply bar/15 23/18*/13 Eq.: -0.946
0.027 0.010 0.006 - 0.973 0.765 0.063
3-ply cubeful prune [grandmaster]
9. Cubeful 3-ply bar/20 24/19 23/18* 21/16 Eq.: -0.957 ( -0.012)
0.021 0.010 0.008 - 0.979 0.781 0.074
3-ply cubeful prune [grandmaster]
The very next turn, White on roll:
DMP
Move number 115: White to play 35
| yeti_yew | 311 |
|---|---|
| |
| PersianLord | 305 |
Position ID: AJBw2zYADOC2XQ Match ID: MIE1AAAAAAAA | |
0.977 0.803 0.111 - 0.023 0.007 0.004
2-ply cubeful prune [world class]
6. Cubeful 2-ply bar/17 Eq.: +0.937 ( -0.017)
0.968 0.772 0.089 - 0.032 0.009 0.004
2-ply cubeful prune [world class]
1. Cubeful 3-ply bar/17 Eq.: -0.959
0.020 0.008 0.004 - 0.980 0.802 0.032
3-ply cubeful prune [grandmaster]
3. Cubeful 3-ply bar/22 24/19 Eq.: -0.976 ( -0.017)
0.012 0.006 0.003 - 0.988 0.825 0.040
3-ply cubeful prune [grandmaster]
According to 2-ply both Blue and White have about 98% game winning chances. According to 3-ply, both players have about 2% GWC.
If you're saying "Huh?" check the pipcounts. Blue's homeboard is lower left.