TCEC Cup rules

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TCEC Cup - Rules & Information


1. Event

a. For all TCEC Events, engines will be invited by the organizers.
b. The TCEC Cup is a knockout format played in TCEC, including all invited qualifying participants.
c. The 32 qualifying engines consist of the top 32 ending participants of TCEC Season, dropping those that are out of apparent development.
d. These engines will be seeded according to their respective final results in the TCEC League Season's final standings.
e. The winner of the last TCEC Cup will be seeded number 1.

2. TCEC Cup knockout matches format

a. The TCEC Cup will take place after the TCEC Swiss.
b. It will be a knockout championship with the 32 participants divided into brackets.
c. The top 8 participants will be seeded in the first round according to the following procedure called Equal Distance Pre Seeding of 8 with Randomized Remaining Contestants (EDPS8-RRC):
1. The top 8 engines in the final standings of the last completed TCEC league event before the Cup will be equal distance pre-seeded;
2. The other 24 qualifying engines will be placed randomly in the remaining open places in the bracket.
d. The TCEC Cup will consist of a total of 32 matches divided into 5 rounds: round of 32, round of 16, quarter-finals, semi-finals, bronze match and final.
e. For an engine to win the TCEC Cup gold medal it must win a total of five matches. The two losing semifinalists will play a match for 3rd and 4th place (`small final’).

3. Matches and tiebreaks

a. Each of the matches will consist of pairs of games (every second with reversed colors and the same opening), the number depending on the round. Cutechess-cli will adjudicate the match if a decisive result has been reached within the set number of games.
b. The lower seeded engine will start playing with the white pieces.
c. In the first round of 32 a set of 2 game pairs is played; in the round of 16 a set of 3 game pairs is played; in the quarter finals a set of 4 game pairs is played; in the semifinals a set of 6 game pairs is played; in the bronze match a set of 8 game pairs is played, and in the final a set of 12 game pairs is played.
d. In case of an equal score after the initial game pairs (2, 3, 4, 5, or 6, as described above) have been played, a tiebreak will be played out immediately.
e. A tiebreak consists of as many additional game pairs that are needed to achieve a single decisive game pair.

4. Openings books

a. All matches are played with a book exit from one of the six opening books in use: these books are referred to as Book32, Book16, Book8, Book4, BookBronze and BookFinal.
b. All six books have been pre-randomized to ensure unpredictability in the occurrence of specific exits.
c. All games take place in pairs in which both engines each play each side of every book exit. Engines will play both sides of each position selected. Openings chosen will roughly approximate human games in terms of their frequency. A new opening should thus occur every other game, then the reverse game is played, so two games in a row from the same starting book position. Because each engine will thus play both sides of every opening, fairness is guaranteed.
d. The Books used in the TCEC Cup Event are assembled by Eduardo Sauceda (Cookie_Monster_71) and Bastiaan Braams (kbg519v1a). These consist of relatively short, variable-length lines that are known in high-level human play. The bias ranges from moderate in the early rounds to high (DivP and SuFi-level) near the end.

5. Time control

a. Time control will be 30 mins + 3 secs increment per move for all games in a match, including the tiebreakers.
b. If an engine loses on time, that results in a loss and will be registered as such. The game will not be replayed.

6. Game ending

a. A game can end in a draw by three-fold repetition, 50-move rule, stalemate, tablebase adjudication, and the new TCEC draw rule under 6.b..
b. The improved TCEC draw rule applies when a game has reached a position with 6 or fewer pieces (including kings, excluding pawns) and where the engine evaluation of the move leading to the position was in [-0.25,0.25]. The game is adjudicated as a draw if the draw rule applies on 8 consecutive plies. The counter resets to 0 in the follwing cases: (1) if the draw rule ceases to apply because of a pawn promotion causing a 7th piece to appear, or (2) an evaluation outside of the [-0.25,0.25] range or the absence of an evaluation by an engine appears. There is no reset for capture or pawn move, and no stipulated minimum move number for adjudication.
c. Cutechess-cli will adjudicate positions with 6 pieces automatically with Syzygy tablebases.
d. A game is won by mate, opponent's illegal move, opponent's resignation, or by tablebase adjudication.
e. If an engine loses on time, the result will not be changed nor the game replayed.

7. Crashes

a. Engine crashes are counted as losses.
b. In case of a server disconnect, or time loss due to lag, or other interruptions not caused by the engines there are five possible scenarios:
i. If the web server crashes, the game continues unaffected, and broadcasting will be resumed as soon as possible;
ii. If the evaluation of both engines is equal to or more than ABS(10) at the moment of game server interruption, the game is scored as a win;
iii. If the evaluation of both engines is equal to or less than ABS(0.15) at the moment of game server interruption, and both engines have completed 35 moves, the game is scored as a draw;
iv. If a game interrupts with 7 pieces on the board, position on the board at the instant of game server interruption will be adjudicated according to 7-man EGTB;
v. In all other cases the game is restarted from the position that the two engines reached before the disconnect, with time compensation to fill up the cache.
c. Whether a game is immediately restarted or played rather at the end of the round will be decided by the responsible TCEC staff.

8. Engine Updates

a. Under no circumstances are updates and fixes to engines allowed once the Cup competition has started.

Further information

See also