TCEC (Top Chess Engine Championship) is a computer chess tournament organized and maintained by Chessdom in cooperation with Chessdom Arena. The goal is to provide the viewers with a live broadcast of long time control, quality chess - played strictly between computer chess engines created by different programmers. One Season is divided into several Stages and lasts about 3-4 months. The winner of the Season will be the TCEC Grand Champion.

Season 11: --tbd-- | Season 10: Houdini | Season 9: Stockfish |Season 8: Komodo | Season 7: Komodo | Season 6: Stockfish | Season 5: Komodo | Season 4: Houdini | Season 3: N/A | Season 2: Houdini | Season 1: Houdini

Martin Thoresen, Marit Thoresen, Paolo Casaschi, Matthias Gemuh and Jeremy Bernstein.

Top Chess Engine Competition (TCEC) differs from other chess tournaments in that it is a competition between highly-rated chess programs (which we interchangeably call ‘engines’) at long time controls on very strong hardware. The result is oftentimes chess that is barely comprehensible to your average club player and greatly impresses grandmasters with the precision and beauty seen in the best games of the competition.

One of TCEC’s conventions is that we almost never play from the usual starting position. The reasons for that are simply that some engines—not all, but some—tend to follow repetitive patterns, resulting in a disproportionate number of games in its favorite opening. We prefer to see engines deserving the title of ‘champion’ to play and prevail from a variety of opening systems. Thus, we have experts in the field select openings months ahead of time, before they know who will be playing them. This human element does introduce a small degree of luck, yet the best programs have invariably risen to the top.

This season is one more time spearheaded by opening expert Nelson Hernandez (USA), known to TCEC fans by his nick of Cato the Younger and more recently (since we changed chat servers) as Cato_Junior. Nelson confesses that he is not actually a chess player at all but a tireless data-collector. He has one of the world’s most extensive collections of non-bullet engine games, numbering well into the tens of millions, with a large number of positions pre-analyzed. Uniquely, all of his games are adjudicated to match their 6-man EGTB or ending position. He has been doing this work since 2004. Nelson was also a member of Anson Williams’ Freestyle chess team, which won three major Freestyle tournaments in 2007-2014.

Openings for the Superfinal were selected by Jeroen Noomen. Jeroen is one of the longest-active persons in computer chess, having first gotten interested in the then-emerging hobby of computer chess in the early 1980s. He participated in numerous live computer chess tournaments in the 1990s and 2000s and was in charge of the opening book in chess programs Rebel and Rybka. He produces a number of opening suites and is recognized as one of the leading figures in computer chess opening theory. Jeroen’s openings in TCEC Season 9 were widely lauded for their topicality and tension.

Nelson Hernandez explains, “Conversion to a league system entails some significant changes to how we will deploy opening positions in TCEC going forward” and goes on to explain the choices in each division in Season 11.

Fourth Division

The junior division in competition will play the same set of openings every season. 28 rounds consisting of the 14 most-common two-move opening positions in the Catobase will be played. In each round all four games between the eight engines will start from the same opening position. Six openings will start 1.e4, six will start 1.d4, one 1.Nf3 and one 1.c4.

Third and Second Division

28 rounds consisting of 14 two-move opening positions shall be played. In each round all four games between the eight engines will start from the same opening position. The difference is that each season the 14 openings will be completely different and drawn from the top 100 most-common openings two-move opening positions in the Catobase, excluding positions used in the Fourth Division.

First Division

First Division will consist of four double round-robins. The first of these four round-robins (56 games in total) will be bookless: every engine will play every other engine from both sides of the board from the traditional starting position. The subsequent three round-robins (168 games in total, 84 openings) will be selected by a TCEC fan, operating within TCEC guidelines. For Season 11 Nikolaos Konstantakis is our guest expert; he has chosen 84 five-move openings for this inaugural season of league competition.

Premier Division

Premier Division will consist of six double round-robins. The first of these six round-robins (56 games in total) will be bookless. The subsequent five round-robins (280 games in total, 140 openings) will be selected by Cato and be eight moves in length. Each season the openings will be completely different though similar in general composition. Book-exit positions will have occurred no less than 500 times in the Catobase and meet other criteria for draw-rate, balance, material and skew.

Superfinal

The Superfinal will be 100 games in length. The first two games will be played from the traditional opening position. The remaining 98 games (49 openings) will be of variable length and be chosen by Jeroen Noomen.

Event
The Top Chess Engine Championship (TCEC) Season 11 is the annual premier championship for chess software. It is a competition between 30 engines with ELO 2800+ and is divided into five divisions and a Superfinal.
TCEC runs 24/7 until all games have been played. One game is played at a time - the next one starts automatically.

Time control
Classical time control will be used through the season and it is increased the deeper the Season goes. For Division 3 and 4, the time control is 30 minutes + 10 seconds added per move for the whole game. For Division 2, the time control is 45 minutes + 10 seconds added per move for the whole game. For Division 1, the time control is 60 minutes + 10 seconds added per move for the whole game. For Division Premier, the time control is 90 minutes + 10 seconds added per move for the whole game. For the Superfinal, the time control is 120 minutes + 15 seconds added per move for the whole game. If an engine loses on time, the result will not be changed or the game replayed. If the TCEC game server locks up at any time during a game (BSOD, freeze etc), that game will be restarted unless the last position was a 6-man or less tablebase position, then it will be manually adjudicated. Prior to Season 9, different time controls have been used. Check the individual games in the "Archive page"" for info.

Game adjudication
A game can be drawn by the normal 3-fold repetition rule or the 50-move rule. However, a game can also be drawn at move 40 or later if the eval from both playing engines are within +0.05 to -0.05 pawns for the last 5 moves, or 10 plies. If there is a pawn advance, or a capture by any kind, this special draw rule will reset and start over. In the website this rule is shown as "TCEC draw rule" with a number indicating how many plies there are left until it kicks in. It will adjudicate as won for one side if both playing engines have an eval of at least 6.50 pawns (or -6.50 in case of a black win) for 4 consecutive moves, or 8 plies - this rule is in effect as soon as the game starts. In the website this rule is shown as "TCEC win rule" with a number indicating how many plies there are left until it kicks in. Cutechess will also adjudicate 5-men or less endgame positions automatically with Gaviota tablebases. The Gaviota adjudication ignores the 50-move rule.

Engine Ratings
When you enter "Archive page" in the File menu, you can see the official TCEC ratings in the bottom right corner - it is updated after each Division or Superfinal and is calculated by using Ordo. The calculation is global and will always include all new and previous games since Season 4. Any games with losses on time, stalls or disconnections are discarded, as are engines that has only losses. If there is a new engine entering TCEC for the first time, it will get a "temporary" rating taken from the CCRL 40/40 4CPU list. If an engine isn't found here, or if it has played very few games, an approximate ELO rating will be given to that engine based on tests from the programmer. Then after this new engine has played an event, the official rating will be calculated using Ordo as explained earlier.

Engine Updates
Only engines that promote to the Superfinal will receive updated versions. All other engines that promote to the next Division will use the version initially submitted. Promoting engines may update UCI/xboard settings. The deadline for engine submission is the last game of the current Division unless the programmer is given a specific deadline from the Tournament Director - the goal is to be able to start the next Division as soon as possible without any significant delay.

Critical Engine Bugs
In the case of a serious, play-limiting bug (like crashing or interface communication problems, not including losses on time) not discovered during the pre-Season testing, the engine can be updated once per Division to fix this/these bug/bugs only. If this update still doesn't fix the problem(s) or if there is no update available, the engine might have the number of cores reduced, have the hash size reduced or have the tablebase access disabled - these changes will remain for the rest of the Division.

Tiebreaks
If necessary, tiebreaks can be used to determine advancement. For all Divisions (not the Superfinal), the first tiebreak criteria is the "crash" tiebreak, meaning that if an engine has crashed once or more during the Division, it will fail qualification versus another engine that has not crashed if both of them has the same amount of points. The Sonneborn-Berger criteria is the second. If still a tie, the greatest number of black games decides. The next criterion is the greatest number of wins, then the greatest number of wins with black. In case of still being tied, then the direct encounter between the tied engines decides. If they are still tied, then the tournament director decides which engine gets the promotion.

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The TCEC Division System - Season 11
As soon as a Division starts, it will run 24/7 until all games have been played. One game is played at a time - the next one starts automatically. There will be a short break between the Divisions, to make sure everything is ok with the TCEC game server and to prepare for the next Division.

Division 4
Division 4 is the preliminary Division, involving 8 engines, playing a double round robin (56 games). The time control of the games will be 30 mins + 10 sec/move. The top 4 engines qualify for Division 3 while the rest are out of TCEC for the current Season.

Division 3
Division 3 consists of the 4 engines that qualified from Season 10 plus the top 4 engines from Division 4. It is a 2x double round robin (112 games). The top 2 engines promote to Division 2 and the bottom 2 engines are relegated.

Division 2
Division 2 consists of the 6 engines that qualified from Season 10 plus the top 2 engines from Division 3. It is a 2x double round robin (112 games). The top 2 engines promote to Division 1 and the bottom 2 engines are relegated to Division 3.

Division 1
Division 1 consists of the 6 engines that qualified from Season 10 plus the top 2 engines from Division 2. It is a 4x double round robin (224 games). The top 2 engines promote to Division Premier and the bottom 2 engines are elegated to Division 2

Division Premier
Division Premier consists of the 6 engines that qualified from Season 10 plus the top 2 engines from Division 1. It is a 6x double round robin (336 games). The top 2 engines promote to the Superfinal and the bottom 2 engines are elegated to Division 1

Superfinal
This match is played with 50 different openings so that each engine plays both black and white of the same position. The match will be presented with opening 1 used in games 1 and 2, then opening 2 used in games 3 and 4 etc. If the match is theoretically won for one side before game 100, the match will still continue until all 100 games have been played. In the case of a drawn match there will be a rapid match of 16 games with a time control of 25' + 10" with random openings selected from earlier in the same Season. In case it is still tied there will be a Blitz match of 8 games with a time control of 3' + 2". When the Superfinal is over, the current Season ends.

The TCEC Grand Champion
The winner of the Superfinal will be crowned the TCEC Grand Champion and will keep this title until there is a winner in the next Superfinal. There is no automatic qualification for the reigning Grand Champion, it will have to go all the way through the next Season for it to be able to defend the title.

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Engine Specific Configuration
UCI and Xboard (Winboard) engines are supported. To identify the protocol an engine is using you can click the gears next to the engine logo during a game. This info will be saved for the archive, but does not work for Season 5 or older games.

Compiles
Many engines come with different .exe files. 64-bit .exes are always preferred over 32-bit. Also, compiles that support SSE 4.2, AVX/AVX2 or similar instruction sets are preferred. Engine authors are free to send an optimized binary for each Division.

Large Pages
Some engines can utilize a function in Windows called large pages, that gives a speed boost. However, after a while the memory in the computer will be fragmented, so that one engine might receive large pages and the opponent won't, which would be unfair. Therefore, this has been disabled. Large pages are often useful when you are running infinite analysis on a position.

Number of Cores / Threads
Each engine can use up to 43 cores of the processors, if this is supported. Some engines have a prefix like "deep", but this has been omitted from the engine name to make it shorter. When watching a game you can see the number of cores that are in use for the engines currently playing by clicking the gears next to the engine logo.

Split Depth
The split depth parameter basically defines the minimum depth for work to be split between threads. If no specific settings are given from the programmer, the default value will be used.

Main Hash Size
Each engine is allowed to use up to 16384 MB of hash. Not all engines supports this much hash, so the maximum for that engine will be used in this case, typically 2048 MB or 4096 MB. When watching a game you can see the size of the hash that is in use for the engines currently playing by clicking the gears next to the engine logo.

Minor Hash Sizes
Some engines have an option to configure the size of other hash tables, often called pawn hash or evaluation hash. The combined, total limit for hash types like these is 4096 MB (8192 MB in case of the Superfinal).

Own Opening Book
All opening books shipped with the engines are removed and/or disabled and any engine found to be using hidden, internal opening books will be disqualified and replaced with another engine chosen by the Tournament Director.

Endgame Tablebases
For Season 11 all divisions, 5-men Nalimov/Gaviota/Scorpio, and 6-men Syzygy are available thanks to the 256 GB SSD. When watching a game you can see the type of the tablebases (if any) that is in use for the engines currently playing by clicking the gears next to the engine logo.

Ponder / Permanent Brain
Basically this means that the engines can think during their opponents turn. It is not allowed so it will be disabled because of performance limitations with only 1 computer. This might change in a future Season of TCEC.

Contempt / Draw Score
Some engines have a setting that can adjust their own view of the positions throughout a game to avoid draws. This setting is not changed from the default unless it is a request from the programmer.

Other Settings
Any configurable option not described above, are not normally adjusted in any way, except if the programmer of an engine wants specific settings for each specific Division. Options like "keep hash tables" or similar is usually enabled.

Season 11 server
CPUs: 44 Cores -> 2 x Intel Xeon E5 2699 v4 @ 2.8 GHz
Motherboard: Supermicro X10DRL-i
RAM: 64 GB DDR4 ECC
SSD: Crucial CT250M500 240 GB
Chassis: Supermicro
OS: Windows Server 2012 R2

Thanks to the devoted audience and its support, the server has received a huge upgrade from Season 10 on, allowing TCEC to start with a 44 cores machine right from Division 4. Pre-Season 8 TCEC Server
CPUs: 2 x 8 core Intel Xeon E5-2689 @ 3300 MHz
CPU Coolers: 2 x Corsair H80i
Motherboard: Asus Z9PE-D8 WS
RAM: 64 GB Kingston KVR16R11D4K4/32 Reg/ECC
PSU: Corsair AX 760
SSD: Samsung 840 Pro 128 GB
Chassis: Silverstone Raven RV03B-WA
OS: Windows 7 Professional

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Is this the official World Computer Chess Championship?
No, it is not, although some people regard it as such.

Who is the reigning TCEC Grand Champion?
Houdini defeated Komodo in the Superfinal of Season 10, so Houdini is the reigning TCEC Grand Champion.

Did the engine move instantly?
Yes, some engines can move from hash, or move instantly. However, sometimes it can seem that it moves instantly but in reality it doesn't, since there is a transmission delay from the playing server to the website by approximately 15 seconds. Refer to the "move time" for each engine to see how long it thought on its move.

Is there a special plugin required to view the games?
No, to view the games it is only required that you allow Javascript to run. The TCEC Web GUI has been developed on the latest Chrome, but will also run fine on the latest Firefox. There is no support for Internet Explorer versions below 9.

What GUI are you using to play the games?
To play the games a special version of cutechess-cli is used. This is a command line tool without an actual GUI. This was made possible thanks to Jeremy Bernstein. Previously TCEC used ChessGUI by Matthias Gemuh.

What is the name of the web framework that displays the games?
It is called pgn4web and is totally free. Paolo Casaschi is the mastermind behind it and has helped a lot on certain difficult programming challenges.