After a three year hiatus the same participants as in Tilburg 2011 found their way to Leiden (The Netherlands):

  • GnuBG, a real Backgammon veteran, represented by Nardy Pillard as in 2007
  • Palamedes by Nikolaos Papachristou
  • BGBlitz

Different to 2011 Palamedes now supports the doubling cube so the usual international rules were used and we played best-of-three 15-point matches.
It has been two of the hottest days in that year, and the weather was only one factor :)

It began with the classic match GnuBG - BGBlitz. The first match was pretty lopsided. BGBlitz achieved good positions several times but until the 13-3 all approaches have been countered by GnuBG. After that BGBlitz had better rolls but at 10-14 GnuBG put an end to it.
The second match started in favor of BGBlitz with a 4-0. An exchange of blows developed until the sixth game with the score 8-6. BGBlitz came under pressure, took the cube and saved itself in an 1-4 backgame. A 44 made GnuBG's position fragil and a few moves later BGBlitz hit a Blot. After the home board was prepared the cube was given and GnuBG had to leave its anchor twice. After the second break the lights went off, BGBlitz won a gammon and equated the score to one match each.
The third match was totally lopsided. In every match BGBlitz rolled one or two joker rolls so GnuBG had not the slightest chance and lost 15-1.
Both programs performed excellent (BGBlitz : 1.07, 0.36 and 0.39 / GnuBG 0.35, 0.23 and 0.14).

Then followed the first match of BGBlitz vs. Palamedes. Although BGBlitz played nearly perfectly with a PR of 0.22 the match went up to the 4-9 in Palamedes' direction. In the sixth game after a classic split, 55, dance, it was a pass at this score but Palamedes took the cube without fear. Four moves later the error happened that decided this match when Palamedes doubled to 4. In spite of a winning probability of 69% the potential redouble makes this an error worth more than a half point. And as it often happens, BGBlitz got a shot, doubled to 8 only 3 moves later and won a gammon with a little luck.
In this match Palamedes played a performance rating of 7.11, where about 75% are due to cube errors.
The first day was awesome for BGBlitz... whether this will remain? The second match against Palamedes was a head-to-head race until the 10-10. The 13th game at the score of 10-13 showed why Backgammon is sometimes referred to as the cruelest game. BGBlitz doubled in the fourth move, which was a double/take but after move 21 it had only a 15% winning chance remaining. BGBlitz got a lucky shot and in the following prime-vs-prime succeeded with a tiny timing advantage to force Palamedes to break his prime and to keep the own one. At that point BGBlitz had a 97.5% winning probability. And why this is cruel? Because the 97.5% were not enough! A blot which wasn't to avoid, which was hit over and over again until the race was lost.
Now to the decisive match. Palamedes had a lightning start and in spite of some errors lead 8-0 quickly after only three games. BGBlitz fought back until the 11-14 Crawford where it went under in spite of the better game play (0.22/0.71/1.25 vs 7.11/4.10/6.59).

Now it was GnuBG vs Palamedes. In the first match it was a head-to-head until the 4-4 when GnuBG made point by point until the score of 12-4. Then Palamedes won two single games and the next game was an interesting prime-vs-prime where Palamedes won a Backgammon and evened out. Palamedes utilized the momentum and won the first match.
In the second match GnuBG had a streak and lead 8-0 and 12-3. Though Palamedes caught up, the advantage was too large so it was 1-1.
In the third match Palamedes had a good start but GnuBG outpaced soon and won 15-7. GnuBG played (2.06/0.26/.48) and Palamedes (7.53 / 3.72 / 5.06).

Now all participants had one win and all matches had been 2:1 so a perfect dead race. We decided on a single 7-point match as Tie-Break.

BGBlitz started against GnuBG and lost 4-7. Again both played on an excellent level (BGBlitz 0.86 / GnuBG 0.36).
The next was BGBlitz against Palamedes. Although BGBlitz outplayed Palamedes (BGBlitz 0.67 / Palamedes 7.79) the luckier dice brought the decision in favor of Palamedes.
Now a real final came up: GnuBG vs. Palamedes. The result 0-7 didn't express that the game was exciting especially the decisive third game with a lot of swings but then again Palamedes won and so got its second title after 2011 (GnuBG 0.24 / Palamedes 4.42) . Congratulations!

On average over all matches BGBlitz played a 0.68, GnuBG played a 0.55 what excels the level of the best human players by far. Only 3 Humans have currently records with a PR below 3.0, Masayuki Mochizuki (better known as Mochy) with 2.85, Michihito Kageyama (better know as Michi) with 2.95 and Neil Kazaross with 2.97. Palamedes played a 5.75 which is (when enough matches are recorded) a Master M3 (the lowest Master level (1 is btter than 3), above is Grandmaster level 1/2/3 and the Super Grandmaster level 1/2/3).

The event was an enjoyable experience, it happened in a very friendly and relaxed atmosphere, and the organizers deserve a big "thank you" for their great work.

You can find the matches here

Here are some photographs from Leiden 2015. Many spectacular views. Historical and modern buildings at one place.
Atmosphere in Leiden
Many other competitions, here the World Computer Chess Championship
image of Nikos and Nardy
Nikos and Nardy at work
Image of Nikos and Frank
Nikos and Frank.
winning ceremony
The winning ceremony.
picture of a windmill
Leiden has many attractive spots.
a gracht
In the center rivers and canals are typical.
Image of houses at the Oude Rijn
The Oude Rijn
picture of a bridge
Lovely places everywhere
Image of a microscope from van Leeuwenhoek
An original microscope from van Leeuwenhoek. Only 260 years later microscopes of this quality could be reproduced and it is not known until today how van Leeuwenhoek made the lenses.
Image of a early anesthesia mask
An early anesthesia mask. You find many other unique pieces in the Boerhaave museum. A visit is highly recommended.