Saturday, September 26, 2015

Season 8 stage 2 stats after first round robin

These are the rankings at the halfway point:

Houdini with two wins improved its position and is back in third. Nirvana lost two games and is back in the difficult qualification struggle. With only one point separating the engines in ranks 5-10 qualifying is going to be tough.

Fire managed to reach a queen and pawns endgame against Gull, it had a pawn advantage and according to the 7-piece tablebase it was a win. However it could not convert the tricky win and could only manage a draw after 50 futile moves. Fire still has no win in this stage, but it still has a shot at qualifying.

The main attraction of rounds 10-11 was undoubtfully the Komodo-Stockfish game. This was the first of probably more that 100 games these two top engines will play this season. It had almost no implication for the qualification of this stage but everyone wanted to see the outcome, especially if one engine won. The game was very tense for the first 25 moves, mainly because Komodo kept an eval of more than 0.3 and any small jump upwards could mean the beginning of the end for Stockfish. In the end Stockfish held the game and Komodo's eval got back to zero, and at least the draw was rather quick.

Instead of the usual notable game I'll finish this post with the halfway stats.

Draw rate, wins

 The draw rate is now at 60.6%, still high but much better than in the first rounds of the stage.

Moves per game

Average = 80.48
Median = 71.25

That's a strange looking distribution. The games are longer in this stage compared to stage 1. The distance between the average and median is the result of having extra long games

Time per game (hours)

Average = 4:47
Median = 4:48

The games are over one hour longer than stage 1, reasonable since each engine has 30 more minutes to think and the games have more moves.

Since the openings are pre-selected for the first two moves there is no point looking at the first move stats.

Using ECO codes there were 48 different openings. The top 3 ECO codes were:
A01 3 times - Nimzovich-Larsen attack
A30 3 times - English, symmetrical variation
B22 3 times - Sicillian, Alappin's variation

Using full opening name there were 63 different openings, almost no repetition so the work of organizers was a success. There were three openings that were repeated twice:
- English: Closed
- Neo-Gruenfeld, 6.O-O c6 7.Nbd2 Bf5
- Queen's Pawn: Modern

Using only the first letter of the ECO codes we get the following distribution:

The 'A's have it in this stage.

If we use the opening 'family name' (using format FAMILY_NAME: VARIANT....) the top 3 are:
English - 14 times
Sicilian - 11 times
QGD - 5 times

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