A short history of TCEC, part 2

This is the second and final part of the history of TCEC, so far.

A short history of TCEC, part 1

Season 6:
Before season 6 (the nTCEC numbering was abandoned) started the site was redesigned to what we have today, a new system for choosing openings was implemented with the help of Nelson Hernandez (aka Cato the Younger),  and Syzygy 6-man tablebases were added for the benefit of any engine that could use them. Stockfish and Komodo were updated constantly as always, and Houdini had a new version 4. Komodo's tablebase use was introduced in the later stages of the season.

In the first stage the engines were divided into 3 groups of 12, each group played a RR, the top 5 qualified as well as the best 6th place for a total of 16 qualifiers. The second stage was again a RR with 8 qualifiers. The third stage was a 4-RR with 4 qualifiers: Stockfish, Houdini, Komodo and Critter (tiebreak for fourth place with Fire and Gull, Rybka a distant 7th place). The fourth stage was a 16-RR, Stockfish won and Komodo came in second, their mini-match result was a draw 2-2. Both engines beat Houdini in this stage, 4-2 and 4-1 resp. Critter, which was no match to the other engines, was a distant fourth.

The final match between Stockfish and Komodo had 64 games. This time Stockfish's dominance throughout the season continued in the final. By game 18 the result was 4-0 and after game 28 it was 5-1, after game 40 it was 9-3, the end result was 13-6 with 45 draws. After two second places Stockfish was the champion of TCEC season 6.

In the break before the next season starts TCEC hosted a short Fischer Random Chess (Chess 960) tournament. This was interesting and weird, the non-canonical start positions generated chess games that had a totally different flavor to what we are used to. There were 8 engines in the tournament, playing a 4-RR. Stockfish proved to be almost invincible in this tournament, with a final result of 25 points out of 28 and only one loss.

Season 7: 
Tablebases were disabled completely in this season, except for game adjudication. Houdini stayed with the same version as season 6, apparently its developer abandoned the project. Stockfish and Komodo continued to be updated regularly. For the first time Rybka did not participate.

In stage 1 there were two groups of 14 engines, each played a RR and 7 qualifed for the next stage, a total of 14 qualifiers. The second stage was a again a single RR, but this time with no imposed openings, the engines were on their own from move 1. The 8 qualifiers played a 4-RR in stage 3, Stockfish, Komodo, Gull and Houdini were the qualifiers. The fourth stage was a 12-RR, Komodo won and Stockfish came second. Many of the Gull games were decided in this stage, and their result had a significant influence over the end results. Gull mini-matches against Stockfish and Houdini were drawn 4-4 and 3-3, but it lost to Komodo 5-1. Most of the other games ended in a draw, Komodo beat Stockfish 2-1 and Houdini 2-0, and Stockfish beat Houdini 2-1. Of all fourth stages over the seasons the results for this season were the closest, and the identity of the second qualifier was not assured until the final rounds.

The final between Komodo and Stockfish was a 64 game match. All through the season Stockfish was not as convincing or as dominant as the previous season. It was often behind on time, even against weaker opponents. This was also a feature of the final match. After game 16 Komodo opened a 3-1 lead, increasing to 5-2 after game 40. Stockfish managed to reduce the gap to 5-4 after game 56 but Komodo came back to win 7-4 with 53 draws, including a win in the final game (Stockfish seems to give up the last game, happened in three of four finals). Once again Komodo was the TCEC champion.

There was a long break after season 7, much longer than was initially announced. I don't know what went on behind the scenes but things are now back on track, and we are waiting for Season 8 to start, writing a new chapter in the history of TCEC...