Draw rate, wins
Final draw rate was 54.5%.
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
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)
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
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.