Wednesday, January 17, 2018

Season 11 division 2, after 2RR

Crosstable after 2RR
 


The current draw rate is 23/56 (41.1%). This is lower than the division 3 draw rate, and the reason is that the two engines at the bottom of the table are losing most of their games. Restricting to the top 6 engines the draw rate is 16/30 (53.3%)


Jonny is leading the table, confirming its result in season 10 stage 1 which was closer to the engines in division 1 than those in division 2. Laser in 2nd place is a bit of a surprise since it started in division 3 and has a good chance of getting promoted again. Laser's results are also surprising when compared to Fritz, the engine that won division 3. Texel in 3rd is also still in the promotion race only 0.5 points behind Laser.

The candidates for relegation to division 3 are Wasp and Bobcat. They are literally out of their league, scoring 1.5 and 2 points in 12 games against the other engines.

In the second game of the division Fritz crashed against Jonny, not a good start for the division or for Fritz. There was no time trouble and the position was balanced with a small eval advantage for Jonny. This was the only crash in division 2 so far, hopefully the second half will be crash-free.

A few interesting games
 
Texel - Jonny: Texel was ahead on eval after the opening, in a position with no knights and with all pawns still on the board. After several exchanges Jonny equalized and moved in front, with a connected pair of passers in the center. Texel had two passers as well but they were harder to support. Eventually Texel had to give a rook for a bishop to stop the black pawns, leading to a won RB vs BB ending.

Arasan - Fritz: For 30 moves the evals were close to 0 with almost no exchanges. Fritz opened a hole in the enter allowing Arasan to take the initiative. Arasan put pressure on the king side and Fritz gave a rook for a knight to try to get free. This led to a RR vs RN ending and a win for Arasan.

Fritz - Texel: Fritz had an eval advantage that increased after the opening and reached 1.3 when Fritz traded its queen for two rooks. Texel's eval was more conservative, and after the trade dropped to 0. Texel's queen was very active while Fritz' pieces were passive, Texel's eval turned negative after it captured a pawn and was over 1.5 after exchanging bishops in a QN vs RRB position. Fritz was outplayed in the endgame, after losing two more pawns the position was winning for Texel.

Arasan - Texel: The position was closed with most pawns on the board, evals favoring Texel. At move 31 both engines thought they were doing well, but Texel allowed its bishop to get trapped on the queen side and this turned out to be key. When the king side opened several moves later it was Arasan that had a strong king side attack with evals approaching 2. Pressing on the king side let Arasan clear the black pawns on the queen side. Just before adjudication Arasan finally captured the trapped bishop. 

Saturday, January 13, 2018

Season 11 division 3 statistics

Draw rate, wins




Final draw rate was 54.5%.


Game termination

The three most common game termination causes were:
40.2% - TCEC win rule
28.6% - TCEC draw rule
17.0% - TB position

The draw rule is back, much fewer 3-folds compared to division 4.
There were 3 crashes, both Pedone (one crash and one update strike) and ChessBrain (2 time outs) came close to being disqualified with two strikes.

Moves per game



Median= 63
Average= 69.6

The games were generally longer than in division 4, though a smaller fraction of the games 
were very long (only 4.4% were over 130 moves, compared to 10.7%).

Time per game (hours)



Median= 1:15
Average= 1:16

Openings

There were 2-move book openings in this stage chosen by Cato. The first letter of the ECO codes was distributed as follows:



For each round all four games had the same book sequence, and again in the reverse round. There were 14 book sequences, each repeated 8 times.  For some sequences all the openings had similar codes (e.g. Sicillian or Caro-Cann). In others the engines had more freedom to choose (in rounds 16 and 23 there were 5 English variants, one Sicilian, one QGD and one Nimzo-Indian defence).

If we use the opening 'family name' (using format FAMILY_NAME: VARIANT....) the top 3 are:
Sicillian - 25 times
English - 13 times
QGD - 11 times

The engines had a lot of freedom to choose the opening variant. 41.1% of the game pairs repeated the same ECO code twice, and 14.3% repeated the same opening variant. In 26.8% of the game pairs the ECO first letter was not repeated twice.

Reverse pairs, wins


There were 8 game pairs with a 1-1 biased result. However since every opening was repeated in 4 game pairs and only one pair is biased, we conclude that this is not an opening bias but depends on the engines playing.


Reverse pairs, same moves 



Pairs of reverse games diverged very quickly, 28.6% of the pairs diverged immediately after book, 85.7% repeated at most 2 plys. One pair repeated 15 plys after book, Fritz - Ethereal rounds 19 and 26, Russian Game, 2 draws.

Friday, January 12, 2018

Season 11 division 3 final results

Division 3 is finished and the qualifiers for division 2 are Fritz and Laser.

The final crosstable is



According to the rules published on the TCEC main site the last two engines, Ethereal and ChessBrain, will be relegated to division 4. However it is not clear whether this is the final decision.

There were no crashes in the last two RRs. Pedone was a strike away from being disqualified, but it managed to finish its 14 games without crashing. ChessBrain also had two time losses in the first half, but since it was ranked 7th another crash would not have made a difference.

Of the 7 openings of RRs 3-4 two had drawish results. Rounds 19 and 26 were 8 Russian Games with 6/8 draws, rounds 21 and 28 were mostly Pirc and Old Benoni with all 8 games drawn.

Ethereal had a rare win against Senpai in round 22. Senpai got into a worse position after the opening, and had to give a rook for pawns. The game was over quickly, with many pieces on the board and Ethereal with a significant material advantage.

Nemorino managed to beat Fritz in round 23, Fritz's only loss in the division. Nemorino had a strong king side attack that got it a two pawn advantage, and then it traded down to a winning queen ending.

Laser lost to Senpai in round 24, the only minimatch Laser lost in the division. Laser started the game with an eval advantage, Senpai equalized and took the initiative. Senpai exchanged pieces until only RB vs RB were left. Laser's king was under a mating threat, and Senpai's king was able to march forward and join the attack. Eventually Senpai captured the white bishop, winning the game.

Reducing the crosstable to the top 5 engines the ranks are as follows:
Pedone +2, Fritz and Laser +1, Nemorino =, Defenchess -4. This is a bit surprising to me. Fritz, Laser and Defenchess are ranked high mostly because of their positive results against the bottom 3 engines.   

The qualifiers will now join Jonny, Bobcat, Texel, Vajolet, Wasp and Arasan in division 2. I think Jonny has a good chance of qualifying since it had better results than the other 5 engines back in season 10. It's hard to say how Fritz and Laser will do in this division. Division 2 will have 2 double RRs, 28 games per engine, same as division 3. The time control will be 45+10, slightly longer games but still too fast for me.

Wednesday, January 10, 2018

Season 11 division 3 after 2RR

Crosstable after 2RR



Laser and Fritz lead the rest of the engines by 2.5 points and are the obvious candidates for promotion to division 2. Fritz has not lost a game yet, Laser lost two but won the reverse games so it is at least drawn against all the engines.
At the bottom of the table Ethereal and ChessBrain are 1.5 points below their closest rival and are facing relegation. ChessBrain has lost two games on time, I'm not sure whether these losses count as crashes. It was losing these games in any case. On the other hand there is no doubt about Pedone crashing once, and since it took a strike for a bug fix between divisions it is one crash away from being disqualified and automatically relegated.

There have been 7 2-move start positions so far, 8 games for each book sequence. In rounds 1 and 8 there were 8 Nimzowitsch-Larsen openings, 5 of which were black wins which is quite unusual. The games in rounds 7 and 14 were all Sicilian Alapin openings, all 8 were draws.

After a quick glance at the games there is one unusual event that is worth mentioning. In the round 13 game Ethereal vs Nemorino the engines got into a long shuffle in a RB vs Q position. Nemorino had a solid eval advantage close to 3 but Ethereal had a clear fortress and the game was heading for a draw. Nemorino avoided a 50-move draw and the shuffle continued, until on move 145 Nemorino simply sacrificed its queen, leading to a quick loss of the game. Nemorino's PV showed it immediately loses the queen, yet its eval was 1.34 in its favor. What a strange bug, similar to the c7f7 game of last season.

Monday, January 8, 2018

Season 11 division 4 statistics

Draw rate, wins

 

Final draw rate was 46.4%.


Game termination

The three most common game termination causes were:
48.2% - TCEC win rule
19.6% - 3-fold repetition
16.1% - TB position

The number of 3-fold repetitions was unusually high, the engines preferred repeating over lowering the eval to 0 and adjudication. There were 3 crashes, Pedone came close to being disqualified with two crashes.

Moves per game



Median= 55
Average= 65

The distribution has unusual peaks, in particular there were 6 games (10.7%) with more than 130 moves. This was mainly because some engines had problems evaluating drawn positions.

Time per game (hours)
  
Median= 1:13
Average= 1:13

Openings

There were 2-move book openings in this stage chosen by Cato. The first letter of the ECO codes was distributed as follows:


For each round all four games had the same book sequence, and again in the reverse round. There were 7 book sequences, each repeated 8 times. For some sequences all the openings had similar codes (e.g. Sicillian or French). In others the engines had more freedom to choose (rounds 3 and 10 were either QGD or Indian defences, and one Benoni).

If we use the opening 'family name' (using format FAMILY_NAME: VARIANT....) the top 3 are:
Sicillian - 16 times
Caro-Kann - 8 times
French - 8 times

The engines had a lot of freedom to choose the opening variant. Only 18% of the game pairs repeated the same ECO code twice, and none repeated the same opening variant. In 7.1% of the game pairs the ECO first letter was not repeated twice.

Reverse pairs, wins

 

The 3 "biased" results all involve Toga, this says more about Toga's ability than the openings which were all very popular, short and unbiased. 


Reverse pairs, same moves 


Pairs of reverse games diverged very quickly, 60.7% of the pairs diverged immediately after book.


Saturday, January 6, 2018

Season 11 division 4 results

Division 4 is finished and the qualifiers for division 3 are:
Defenchess, Senpai, Pedone, Ethereal, and ChessBrainVB

The final crosstable is



The qualifiers were determined in the last round, ChessBrain needed a draw against Senpai to finish ahead of Toga. Senpai was ahead but ChessBrain managed to hold.

There were 5 qualifiers and not 4 because the division 3 engine Fruit was pulled out by its author for unknown reasons.

Pedone qualified despite crashing twice, close to being eliminated by the 3 strikes rule. There was some discussion about whether to allow it to continue crashing in division 3, the ruling was to allow engines to be updated (without testing), at the cost of one strike in the next division. Pedone and Ethereal chose to update, hopefully they will not crash in division 3.

The qualifiers will now be joined with Fritz, Laser and Nemorino in division 3. Fritz and Laser are the favorites to qualify, but nothing is certain until the games are played. Division 3 will have 2 double RRs, 28 games per engine, so less luck is involved than in division 4. The time control will still be 30+10, too fast for me to go over all games and write reports. I'll try to write one at the half point.

Friday, January 5, 2018

Season 11 live blogging, Friday Jan 5th

Season 11 has started with division 4, a quick 2RR with eight engines trying to finish in the top 4 to qualify for division 3. The games are about an hour long each and we are about half way through the stage now playing the reverse games.

Now playing are Scorpio vs The Baron, currently in 7th and 8th place.

move 27: on the board black is a pawn up, with QRN vs QRN on the board. White has a passer on the queen side for compensation.

move 30: The queens are off, evals are negative in favor of The Baron, and increasing. Can Scorpio hold?

move 32: looks like The Baron is going to exchange rooks and take white's passer. My bet is that black will win the knight ending.

move 35: and there we go, Scorpio got a pawn back so The Baron is a pawn up, all pawns on the king side. Evals are at 2, not sure if this is a sure win. The engines could also blunder, especially Scorpio which is in some time trouble.

move 40: the kings and knights are dancing. The PV from The Baron doesn't show a lot of progress, Scorpio is not giving us any PV....

move 45: Scorpio's eval was at 0 for a move, it jumps like that sometimes. Still no pawn moves or captures, evals stable.

move 50: The Baron is expecting a pawn move but Scorpio is giving checks with the knight.

move 58: Eval jump for the Baron, does is see an improvement? The king tries to advance on the queen side.

move 62: There's the white pawn move, a zugzwang? Scorpio's eval jumps to almost 3 and the Baron's PV shows movement on the king side.

move 65: now the Baron's eval jumps to almost 4. This looks like a win for black. Now back to 3, we'll see in a moment.

move 69: pawn exchange on the king side, The Baron's eval over 5 now, probably a win. Scorpio not seeing it yet.

move 75: all over, the white pawns will soon fall.

Scorpio is probably out of the race, the Baron stilll has a small chance, it is 1.5 points behind 4th place with 6 games to go.

My time is up for today, tomorrow the stage will be over and the qualifiers will be decided.