Hm, I'm interested to see your point
It may be no more interesting than your common garden variety boring bot bashing. I think the eval is wrong, and the rollout is wrong, and have just a few thoughts about that.
The score (after 0 games) is: Gnubg Expert 1-point match 0, Me 1-point match 0 (match to 1 point, post-Crawford play)
Move number 18: Me 1-point match to play 45
| Gnubg Expert 1-point match | 111 |
|---|---|
| |
| Me 1-point match | 100 |
Position ID: 2LZbEABbbgUDEA Match ID: cAk2AAAAAAAA | |
• Me 1-point match moves 13/9 13/8
Gnubg evaluations suck: 2-ply evaluation 11.1%, 3-ply evaluation, 9.7%, 4-ply evaluation 10.8%.
I thought and think that White should win 4% to 5%. Call it 5% if you want. In an exhausting 10-trial manual rollout, Blue won 0%. Kids'n'winks but in all seriousness playing this out is tedious but easy, and my over/under line is that a competent player should win at least 95% here.
I don't know why Gnubg can't.
Gnubg best plays suck: 2-ply evaluation 8/3 5/1, 3-ply evaluation 8/4 6/1, 4-ply evaluation 13/8 5/1.
Since White can play 3-3 four times no sweat, I can't see any reason to keep the midpoint.
Over the board, like Chuck, I played 13/8 13/9 and I think that's fine and don't think it should matter much what Blue does. I agree with the readers who suggested playing one down from the midpoint, but (almost entirely) because of the chance that a human opponent or some misguided bot will hit the blot on the midpoint.
Ouf course White should NOT hit that blot if he does not have to, but in response to 13/4, Gnubg 2-ply hits with 5-3 and double hits with 6-3. Not me, no thanks, I'll just roll the prime home and close out one checker.
If Blue plays 13/4, then sometimes White should slot the prime, and then, I think Blue, should hit the slot, and hope to anchor. More on that in a sec --
Gnubg rollouts suck:
After 300+ trials Gnubg insists that 13/4 wins 7.1%. That play might be best, but I don't believe that percentage.
Rollout strangeness #1 is that even though that 7% is inflated with wrong hits (like with 5-3 and 6-3), if White's blot is still in the outfield, Gnubg doesn't hit it. Rollout strangeness #2 is that if White slots in front of the prime, Blue doesn't hit that blot either, even if Blue has double-slotted his home board (it didn't, in the times I played the position out).
I think the best play, if there is one, might be 13/9 8/3, which preserves some chance of forcing an anchor, but doesn't risk getting several checkers sent back.
After about 300 trials, Gnubg had 13/9 8/3 winning about 6.8%, still too high, I think, but it's not inflated by the bad hits that the bot makes after 13/4 but doesn't make after 13/9 8/3.
Apologies for the too-short rollout -- there's still 8 plays in contention but since I think the win %s are all way off and think play #9 is better than most of the other 8, anyway, I'll not continue.
Alert: doubtful move ( -0.021)
Alert: very unlucky roll! ( -0.010)
| # | Ply | Move | Equity | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | R | 13/4 | -0.858 | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 350 games, Mersenne Twister dice gen. with seed 1053643157 and quasi-random dice | ||||||||||||||||||||||
| Play: supremo 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 16 more moves within equity 0.32 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| 2 | R | 13/9 8/3 | -0.864 ( -0.006) | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 271 games, Mersenne Twister dice gen. with seed 1053594590 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| 3 | R | 13/8 5/1 | -0.865 ( -0.007) | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 262 games, Mersenne Twister dice gen. with seed 1053594590 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| 4 | R | 8/4 7/2 | -0.868 ( -0.009) | |||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 261 games, Mersenne Twister dice gen. with seed 1053643157 and quasi-random dice | ||||||||||||||||||||||
| Play: supremo 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 16 more moves within equity 0.32 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| • | 9 | R | 13/9 13/8 | -0.879 ( -0.021) | ||||||||||||||||||
| ||||||||||||||||||||||
| Full cubeful rollout with var.redn. | ||||||||||||||||||||||
| 262 games, Mersenne Twister dice gen. with seed 1053594590 and quasi-random dice | ||||||||||||||||||||||
| Play: world class 2-ply cubeful prune [world class] | ||||||||||||||||||||||
| keep the first 0 0-ply moves and up to 8 more moves within equity 0.16 | ||||||||||||||||||||||
| Skip pruning for 1-ply moves. | ||||||||||||||||||||||
| Cube: 2-ply cubeful prune [world class] | ||||||||||||||||||||||
0.111 0.012 0.000 - 0.889 0.109 0.003
2-ply cubeful prune [world class]
2. Cubeful 2-ply 13/9 8/3 Eq.: -0.781 ( -0.004)
0.109 0.011 0.000 - 0.891 0.095 0.003
2-ply cubeful prune [world class]
3. Cubeful 2-ply 13/8 7/3 Eq.: -0.792 ( -0.015)
0.104 0.012 0.000 - 0.896 0.093 0.002
2-ply cubeful prune [world class]
4. Cubeful 2-ply 7/3 6/1 Eq.: -0.792 ( -0.015)
0.104 0.015 0.000 - 0.896 0.151 0.006
2-ply cubeful prune [world class]
5. Cubeful 2-ply 13/8 5/1 Eq.: -0.792 ( -0.015)
0.104 0.011 0.000 - 0.896 0.168 0.005
2-ply cubeful prune [world class]
6. Cubeful 2-ply 6/2 6/1 Eq.: -0.798 ( -0.020)
0.101 0.013 0.000 - 0.899 0.176 0.006
2-ply cubeful prune [world class]
7. Cubeful 2-ply 6/1 5/1 Eq.: -0.798 ( -0.021)
0.101 0.014 0.000 - 0.899 0.205 0.009
2-ply cubeful prune [world class]
8. Cubeful 2-ply 7/2 5/1 Eq.: -0.799 ( -0.021)
0.101 0.014 0.000 - 0.899 0.176 0.006
2-ply cubeful prune [world class]
9. Cubeful 2-ply 13/9 6/1 Eq.: -0.799 ( -0.022)
0.101 0.014 0.000 - 0.899 0.230 0.018
2-ply cubeful prune [world class]
10. Cubeful 2-ply 8/4 6/1 Eq.: -0.800 ( -0.022)
0.100 0.015 0.000 - 0.900 0.170 0.009
2-ply cubeful prune [world class]
11. Cubeful 2-ply 8/3 7/3 Eq.: -0.801 ( -0.023)
0.100 0.013 0.000 - 0.900 0.105 0.002
2-ply cubeful prune [world class]
12. Cubeful 2-ply 8/3 6/2 Eq.: -0.801 ( -0.024)
0.099 0.014 0.000 - 0.901 0.156 0.005
2-ply cubeful prune [world class]
13. Cubeful 2-ply 13/9 7/2 Eq.: -0.803 ( -0.025)
0.099 0.012 0.000 - 0.901 0.165 0.007
2-ply cubeful prune [world class]
14. Cubeful 2-ply 13/4 Eq.: -0.803 ( +0.058)
0.099 0.013 0.000 - 0.901 0.162 0.008
2-ply cubeful prune [world class]
15. Cubeful 2-ply 7/2 6/2 Eq.: -0.808 ( -0.030)
0.096 0.013 0.000 - 0.904 0.208 0.008
2-ply cubeful prune [world class]
16. Cubeful 2-ply 13/9 13/8 Eq.: -0.808 ( -0.031)
0.096 0.011 0.000 - 0.904 0.085 0.002
2-ply cubeful prune [world class]
17. Cubeful 2-ply 8/4 7/2 Eq.: -0.809 ( +0.052)
0.096 0.015 0.000 - 0.904 0.150 0.006
2-ply cubeful prune [world class]
18. Cubeful 2-ply 13/8 6/2 Eq.: -0.812 ( +0.049)
0.094 0.013 0.000 - 0.906 0.229 0.008
2-ply cubeful prune [world class]
1. Cubeful 3-ply 8/4 6/1 Eq.: -0.806
0.097 0.014 0.000 - 0.903 0.160 0.006
3-ply cubeful prune [grandmaster]
2. Cubeful 3-ply 13/8 5/1 Eq.: -0.806 ( -0.000)
0.097 0.011 0.000 - 0.903 0.155 0.004
3-ply cubeful prune [grandmaster]
3. Cubeful 3-ply 7/3 6/1 Eq.: -0.807 ( -0.001)
0.097 0.013 0.000 - 0.903 0.142 0.005
3-ply cubeful prune [grandmaster]
4. Cubeful 3-ply 13/4 Eq.: -0.808 ( +0.053)
0.096 0.015 0.000 - 0.904 0.150 0.006
3-ply cubeful prune [grandmaster]
5. Cubeful 3-ply 6/1 5/1 Eq.: -0.809 ( -0.003)
0.095 0.013 0.000 - 0.905 0.193 0.007
3-ply cubeful prune [grandmaster]
6. Cubeful 3-ply 13/9 6/1 Eq.: -0.811 ( -0.005)
0.095 0.014 0.000 - 0.905 0.235 0.018
3-ply cubeful prune [grandmaster]
7. Cubeful 3-ply 6/2 6/1 Eq.: -0.812 ( -0.006)
0.094 0.011 0.000 - 0.906 0.159 0.005
3-ply cubeful prune [grandmaster]
8. Cubeful 3-ply 8/3 6/2 Eq.: -0.813 ( -0.007)
0.094 0.012 0.000 - 0.906 0.140 0.004
3-ply cubeful prune [grandmaster]
9. Cubeful 3-ply 8/3 5/1 Eq.: -0.813 ( -0.007)
0.093 0.011 0.000 - 0.907 0.102 0.002
3-ply cubeful prune [grandmaster]
10. Cubeful 3-ply 13/9 8/3 Eq.: -0.816 ( -0.010)
0.092 0.012 0.000 - 0.908 0.087 0.002
3-ply cubeful prune [grandmaster]
11. Cubeful 3-ply 13/8 6/2 Eq.: -0.814 ( +0.047)
0.093 0.012 0.000 - 0.907 0.209 0.007
3-ply cubeful prune [grandmaster]
12. Cubeful 3-ply 13/9 7/2 Eq.: -0.818 ( -0.012)
0.091 0.012 0.000 - 0.909 0.161 0.005
3-ply cubeful prune [grandmaster]
13. Cubeful 3-ply 7/2 5/1 Eq.: -0.819 ( -0.013)
0.090 0.011 0.000 - 0.910 0.163 0.005
3-ply cubeful prune [grandmaster]
14. Cubeful 3-ply 13/8 7/3 Eq.: -0.820 ( -0.014)
0.090 0.011 0.000 - 0.910 0.084 0.001
3-ply cubeful prune [grandmaster]
15. Cubeful 3-ply 7/2 6/2 Eq.: -0.820 ( -0.014)
0.090 0.012 0.000 - 0.910 0.195 0.007
3-ply cubeful prune [grandmaster]
16. Cubeful 3-ply 8/4 7/2 Eq.: -0.823 ( +0.038)
0.089 0.013 0.000 - 0.911 0.137 0.004
3-ply cubeful prune [grandmaster]
17. Cubeful 3-ply 13/9 13/8 Eq.: -0.827 ( -0.022)
0.086 0.012 0.000 - 0.914 0.076 0.001
3-ply cubeful prune [grandmaster]
18. Cubeful 3-ply 8/3 7/3 Eq.: -0.839 ( -0.033)
0.081 0.009 0.000 - 0.919 0.095 0.001
3-ply cubeful prune [grandmaster]
1. Cubeful 4-ply 13/8 5/1 Eq.: -0.784
0.108 0.010 0.000 - 0.892 0.162 0.006
4-ply cubeful prune
2. Cubeful 4-ply 13/9 8/3 Eq.: -0.787 ( -0.003)
0.107 0.011 0.000 - 0.893 0.097 0.003
4-ply cubeful prune
3. Cubeful 4-ply 8/3 5/1 Eq.: -0.792 ( -0.008)
0.104 0.012 0.000 - 0.896 0.112 0.004
4-ply cubeful prune
4. Cubeful 4-ply 13/8 7/3 Eq.: -0.792 ( -0.008)
0.104 0.011 0.000 - 0.896 0.098 0.003
4-ply cubeful prune
5. Cubeful 4-ply 13/4 Eq.: -0.793 ( +0.068)
0.104 0.012 0.000 - 0.896 0.163 0.009
4-ply cubeful prune
6. Cubeful 4-ply 13/9 6/1 Eq.: -0.795 ( -0.011)
0.102 0.012 0.000 - 0.898 0.228 0.022
4-ply cubeful prune
7. Cubeful 4-ply 13/9 7/2 Eq.: -0.798 ( -0.014)
0.101 0.011 0.000 - 0.899 0.169 0.008
4-ply cubeful prune
8. Cubeful 4-ply 13/9 13/8 Eq.: -0.804 ( -0.020)
0.098 0.011 0.000 - 0.902 0.098 0.003
4-ply cubeful prune
9. Cubeful 4-ply 13/8 6/2 Eq.: -0.804 ( +0.057)
0.098 0.011 0.000 - 0.902 0.222 0.010
4-ply cubeful prune
10. Cubeful 4-ply 8/4 6/1 Eq.: -0.805 ( -0.021)
0.098 0.012 0.000 - 0.902 0.164 0.011
4-ply cubeful prune
11. Cubeful 4-ply 7/3 6/1 Eq.: -0.807 ( -0.023)
0.096 0.012 0.000 - 0.904 0.148 0.008
4-ply cubeful prune
12. Cubeful 4-ply 8/3 7/3 Eq.: -0.808 ( -0.024)
0.096 0.011 0.000 - 0.904 0.109 0.003
4-ply cubeful prune
13. Cubeful 4-ply 6/1 5/1 Eq.: -0.810 ( -0.026)
0.095 0.012 0.000 - 0.905 0.206 0.011
4-ply cubeful prune
14. Cubeful 4-ply 8/3 6/2 Eq.: -0.811 ( -0.027)
0.094 0.011 0.000 - 0.906 0.149 0.006
4-ply cubeful prune
15. Cubeful 4-ply 6/2 6/1 Eq.: -0.813 ( -0.028)
0.094 0.011 0.000 - 0.906 0.167 0.007
4-ply cubeful prune
16. Cubeful 4-ply 8/4 7/2 Eq.: -0.813 ( +0.048)
0.093 0.012 0.000 - 0.907 0.150 0.007
4-ply cubeful prune
17. Cubeful 4-ply 7/2 5/1 Eq.: -0.814 ( -0.030)
0.093 0.011 0.000 - 0.907 0.176 0.008
4-ply cubeful prune
18. Cubeful 4-ply 7/2 6/2 Eq.: -0.818 ( -0.034)
0.091 0.011 0.000 - 0.909 0.204 0.010
4-ply cubeful prune