Great job, William! This is a really nice way to present the data, easy
to see and follow. Now, let's see if we can make some sense of it all.
We can assume at scores where one player isn't at 4 points, the programs
will make their "normal" move -- i.e. the move they would make in a money
game. Some match scores might have a slight effect, but for the most
part they won't. Clearly when the score is 4-4, the programs will play
their double-matchpoint strategy. Hopefully at 4-0 Crawford or 4-2
Crawford they will do so also (taking into account the slight backgammon
possibility), since a gammon means only a free drop. However, I'm not
familiar with how these strategies have been programmed in. At 4-1 or
4-3 Crawford, the programs should know that gammons are exceptionally
valuable for the trailer, while they have no value for the leader. Ditto
for 4-1 and 4-2 Post-Crawford. At 4-3 post-Crawford the strategy should
be double-matchpoint strategy since if the game is played it will be with
the cube turned, but I'm not sure how sophisticated the programs are in
I'm going to categorize the opening rolls into 4 categories to help
1) The natural rolls: 3-1, 4-2, 5-3, 6-1, and 6-5.
2) The potential building rolls: 3-2, 5-2, 4-3, and 5-4.
3) The potential running rolls: 6-2, 6-3, and 6-4.
4) The potential slotting rolls: 2-1, 4-1, and 5-1.
I will also give TD's choice of opening plays (to the best of my memory).
1) The natural rolls: All the programs are in agreement about the
obvious play, regardless of the match score. Enough said.
2) The building rolls:
5-4: Both Loner and Jellyfish like 13/8, 13/9 as their normal opening
play. However, when gammon matter, things diverge. Jellyfish appear to
like running with 24/15 when one side or the other can use gammons. Loner
sticks with 13/8, 13/9 when it can use a gammon, but when the other guy is
the one who need a gammon or at double matchpoint it prefers 24/20, 13/8.
TD likes 24/20, 13/8. So we can conclude that all three plays are pretty
close, but the one to get the gammons is bringing the builders down. This
makes sense -- the stronger the attack force, the greater likelihood there
is of a gammon.
5-2: Jellyfish likes 24/22, 13/8 on all the samples we have (we don't
have any when it needs a gammon but its opponent doesn't). Loner, on the
other hand, prefers 13/8, 13/11 as its normal play. However at double
matchpoint or when the opponent needs a gammon it prefers 24/22, 13/8.
TD likes 24/22, 13/8. Once again, splitting plays seem to be preferred
when the main goal is to win the game, while the building play leads to
3-2: Here the programs agree. Both of them prefer 13/10, 13/11 as their
normal play, but when they can't use a gammon they switch to 24/21,
13/11. Again, consistent with the split when you aren't after a gammon
theme. TD likes 24/21, 13/11.
4-3: Jellyfish likes 13/10, 13/9 unless it doesn't need a gammon, in
which case it prefers 24/21, 13/9. Loner appears to like 13/10, 13/9
always. TD prefers 24/20, 13/10.
From these results, we can conclude that TD is much less gammon oriented
than the other nets, which I have noticed by watching its actual play and
3) The running rolls:
6-2: Jellyfish likes 24/18, 13/11 unless it can't use a gammon and its
opponent can -- then it switches to 24/16. Loner sticks with 24/18,
13/11 all the time. TD also likes 24/18, 13/11.
6-3: Jellyfish is a runner -- it always plays 24/15. Loner plays 24/18,
13/10 as its normal move, but if it can't use a gammon or at double
matchpoint is also runs. TD likes 24/18, 13/10.
6-4: Jellyfish prefers 24/14 as its normal move, as well as at double
matchpoint. However when it can use a gammon but the opponent cannot, it
switches to 8/2, 6/2. Loner will play 8/2, 6/2 as its normal move, but
if it can't use a gammon it goes with 24/14. Neither program ever played
the more popular 24/18, 13/9, which is TD's choice. Not surprisingly, TD
thinks making the two point is considerably inferior, since it isn't as
The running plays tended to be better when one didn't need a gammon.
Making the two point with 6-4, a play long thought to be hopeless, is
coming back into vogue as a good gammon producer.
4) The slotting plays. Here all the programs (including TD) reject the
slot in all cases and prefer the minor split. The only exception is on
the opening 2-1 -- there loner will sometimes slot depending on the match
score, although I was unable to determine a pattern. It looks like the
slot, long popular with most experts due to the quick advantage gained
when it works and the more complex types of positions, may not be
Overall, Loner seems to be the most aggressive program as far as heading
for building up a board and going for a gammon. Jellyfish is second,
while TD leans the other way and concentrates on getting the back men
moving more than the other programs.