As part of the 3rd Mind Sports Olympiad, August 1999, various competitors were pitched against computers in their sport. Backgammon was represented by John Broomfield (JB), chosen by the MSO for being the 1998 British Open Champion and the 1998 UK Champion. His opponent was JellyFish 3.5 (JF) playing level 7, 500 setting. We played the best of 3, 11 point matches.
Terms
Dance
A dice roll that fails to re-enter a man off the bar after having been hit.
Equity
The expected value of a backgammon position. Specifically, the sum of the values of the possible outcomes from a given position with each value multiplied by its probability of occurrence.
Volatility
The changeability of the equity of a position. A position of high volatility is one that is likely to see a large change in equity as a result of the player's or the opponent's next roll. A position's volatility is a consideration for a player deciding whether or not to offer a double.
MATCH 1: GAME 1
| JF (Black): 0 |
JB (White): 0 |
| |
| 01) | 52: 13/8 24/22 | 44: 24/20(2) 13/9(2) |
| 02) | 63: 13/4 | 42: 8/4 6/4 |
| 03) | 53: 8/3 6/3 | 31: 8/5 6/5 |
| 04) | 63: 13/4 |
|
According to JF this is John’s optimum time to double:
but John plays on:
| JF (Black) |
JB (White) |
| |
| 04) |
| 52: 13/8 6/4 |
| 05) | 22: 24/22 13/11(2) 6/4 | Doubles to 2 |
According to JF this is wrong:
| Wins | G/BG | Equity |
|---|
| JF | 33.6 | 4.3 |
|
| JB | 66.4 | 8.6 | 0.372 |
|
| Volatility: 0.198 No Double/Take |
| JF (Black) |
JB (White) |
| |
| 06) | Takes | 52: 13/6 |
JB drops down to JF 3rd with this move E: 0.314. If JF plays 13/8 13/11, E: 0.382.
| JF (Black) |
JB (White) |
| |
| 07) | 21: 4/1 | 51: 13/8 6/5 |
| 08) | 63: 8/2 4/1 | 52: 20/13 |
| 09) | 51: 8/2 | 51: 20/15 13/12 |
| 10) | 54: 22/13* | 61: Dances |
| 11) | Redoubles to 4 | Takes |
JF correctly re-doubles here but John makes an error in taking:
| Wins | G/BG | Equity |
|---|
| JF | 70.1 | 40.1 | 0.757 |
| JB | 29.9 | 5.3 |
|
|
| Volatility: 0.576 Double/Drop |
This looks like a foolhardy take offering JF plenty of gammon chances. JF has 1s and 3s to hit with 2s and 4s to cover. If the second blot on the 15-point isn’t hit, JF still has plenty of covering rolls for his 21-point blot.
| JF (Black) |
JB (White) |
| |
| 12) | 32: 13/10* 6/4 | 32: Dances |
| 13) | 41: 22/18 10/9 | 21: Dances |
| 14) | 62: 18/10 | 43: Dances |
| 15) | 62: 10/4 8/6 | 65: 25/20 |
| 16) | 54: 11/6 9/5* | 62: Dances |
| 17) | 63: 11/5 6/3 | 42: Dances |
| 18) | 41: 4/0 6/5 | 62: Dances |
| 19) | 44: 6/2(2) 4/0(2) |
|
A bad roll for JF, now he’s left with 3 men on his highest point - a possible chance for John soon?
| JF (Black) |
JB (White) |
| |
| 19) |
| 22: Dances |
| 20) | 64: 5/0 5/1 |
|
Well, probably John’s final chance to hit...
| JF (Black) |
JB (White) |
| |
| 20) |
| 55: 25/20* 25/10 |
...and he does, in style.
| JF (Black) |
JB (White) |
| |
| 21) | 63: 25/22 | 21: 5/3* 4/3 |
| 22) | 53: Dances | Re-doubles to 8 |
| 23) | Takes |
|
Once again, according to JF this action is incorrect:
| Wins | G/BG | Equity |
|---|
| JF | 28.6 | 2.2 |
|
| JB | 71.4 | 0.0 | 0.407 |
|
| Volatility: 0.227 No Double/Take |
With the pip count JF/45 JB/108, JF has plenty of racing Equity in this game; and so he takes.
| JF (Black) |
JB (White) |
| |
| 23) |
| 43: 10/6 8/5 |
JB plays the careful move here, but it’s JF 11th, E: 0.283; a long way from the best move of 21/16 10/7, E: 0.376, a bit of a riskier shot but promising more potential. If JF is to re-enter and escape with 7s then it’s in JB’s interest to have the blot on his bar-point recirculated.
| JF (Black) |
JB (White) |
| |
| 24) | 53: Dances | 55: 20/5 9/4 |
Again, JB plays the careful move but it’s at JF 3rd, E: 0.293, the better move being 20/10 9/4 8/3, E: 0.307 leaving just a 26 off the bar but offering 27 hits if JF rolls the 7 he needs to escape.
| JF (Black) |
JB (White) |
| |
| 25) | 21: 25/24 3/1 | 64: 9/3 5/1* |
| 26) | 31: 25/24* | 51: 25/20 8/7 |
JB’s move comes in last here at 6th out of 6 with E: -0.041, the best move being 25/20 3/2, E: 0.055, slipping from a negative to a plus equity. This time JF errs on the safer side leaving only one blot (11 hits). If JB is hit twice he is going to risk losing a gammon.
| JF (Black) |
JB (White) |
| |
| 27) | 54: Dances | 33: 20/17 7/1* 4/1 |
JB’s move looks good here, JF 2nd, E: 0.401 and I must admit, I like it too. However, JF doesn’t preferring 8/2 5/2 4/1*, E: 0.463. I can’t see the sense in leaving a direct 1, (11 shots off the bar) with the option of picking up another blot with a 6; unless JF is planning to continue hitting on the 1-point to stop the last checker from escaping - I can understand that.
| JF (Black) |
JB (White) |
| |
| 28) | 44: Dances | 51: 17/12 3/2 |
JB again fails to find the 'best' play with this move at JF 4th, E: 0.391, when he should have played 17/12 5/4, E: 0.409!
| JF (Black) |
JB (White) |
| |
| 29) | 41: Dances | 66: 12/0 8/2 6/0 |
| 30) | 63: Dances | 51: 6/1 6/5 |
| 31) | 41: Dances | 61: 5/0 5/4 |
JB plays it safeish, JF 2nd, E: 0.765 but JF prefers the slightly riskier 5/0 1/0, E: 0.773.
| JF (Black) |
JB (White) |
| |
| 32) | 61: 25/18 |
|
From here on it’s bearoff all the way for JB as he takes the first game 8/0.
| JF (Black) |
JB (White) |
| |
| 32) |
| 44: 5/1 4/0(3) |
| 33) | 41: 18/13 | 51: 5/0 1/0 |
| 34) | 65: 13/2 | 21: 2/0 1/0 |
| 35) | 64: 3/0 3/0 | 51: 3/0 1/0 |
| 36) | 62: 2/0 2/0 | 61: 3/0 1/0 |
| 37) | 63: 2/0 2/0 | 42: 2/0 |
|
| Wins 8 points |
Human leads 8-0
- Michael Crane
| Click here to view the full transcript of Match 1 or right click and "save target as" to download it. |
