Chess News

TCEC Season 8 – complete information

TCEC Season 8 graphics created by Santiago Mendez

TCEC Season 8 graphics created by Santiago Mendez

The Top Computer Chess Championship TCEC Season 8 is scheduled to start this August 21st. The world’s best computer chess software engines will compete through three stages and a final to decide the 2015 TCEC Grand Champion.

Last season the TCEC, which was won by the Komodo engine, attracted hundreds of thousands unique viewers and hit major headlines. Now after a long wait the championship continues. It is sponsored by and the official news partner will be

Official website / Live games and 24h chat / Facebook fan page

This is final list of participants. It was compiled from a preliminary list plus a poll on the facebook fan page of TCEC. After testing, some engines were left out due to software issues (instability, frequent crashes, etc.) and here is the definite participants list for Season 8.

TCEC Season 8 participants

Engine Version
Alfil 15.8
Arasan 18
Arminius 060815
Cheng4 0.39
Chiron 2
Equinox 3.30
Fire 5b
Fruit Reloaded 140815b2
Gaviota 1
Ginkgo 1.2
Gull 3
Hannibal 100815
Houdini 4
Jonny R4447
Junior 13.8
Komodo 9.1
Nightmare 7.96b
Nirvana 81715
Pedone 1.3
Protector 1.9
Scorpio 2.77
Stockfish 150815
Texel 1.06a19
The Baron 3.40a

Update: Stage 1a and Stage 1b groups are now published on Chessdom. In a last minute substitution, Exchess will play instead of Arminius. The later was showing certain instability, forfeiting games on time during the test phase. Read on for the TCEC system of play, format, time controls, specific rules, hardware specifications and more.

Special thanks to Santiago Mendez from for the creatives and graphics of Season 8


Time control
Starting from Season 8, the time control is increased the deeper the Season goes. For Stage 1, the time control is 90 minutes + 30 seconds added per move for the whole game. For Stage 2, the time control is 120 minutes + 30 seconds added per move for the whole game. For Stage 3, the time control is 150 minutes + 30 seconds added per move for the whole game. For the Superfinal, the time control is 180 minutes + 30 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 8, the fixed time control for all events was 120 minutes + 30 seconds added per move for the whole game.

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 tablebase endgame positions automatically.

Opening Book
TCEC uses openings put together by Nelson Hernandez and Adam Hair, with assistance from Erik Kislik. Stage 1 will run without opening books. Stage 2 will use a depth-limited opening book of 2 moves. Stage 3 and the Superfinal will use an opening book of 8 moves.

Engine Ratings
When you enter “Archive mode” in the File menu, you can see the official TCEC ratings in the bottom right corner – it is updated after each Stage 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 are discarded, as is engines with 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 single CPU list. If an engine isn’t found here, or if it has played very few games, the CEGT 40/20 single CPU list is used instead but the rating difference between Houdini 3 64-bit in the two rating lists will be added to the rating. If an engine isn’t found in either list, 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. If an engine is updated to a new version, this new version will inherit the rating of the old version.

Engine Updates
The engine programmers can provide updates only before an event starts, not during. However, there will be no extra testing meaning that this is a gamble if the engine could be unstable. The deadline for engine submission is the last game of the current Stage – the goal is to be able to start the next Stage 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 discovered during the pre-Season testing, the engine can be updated once per Stage 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 Stage.

If necessary, tiebreaks can be used to determine advancement. For all Stages (not the Superfinal), the first tiebreak criteria is the “crash” tiebreak, meaning that if an engine has crashed once or more during the Stage, 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.

The TCEC Season System – Season 8
As soon as a Stage 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 Stages, to make sure everything is ok with the TCEC game server and to prepare for the next Stage.

Stage 1
Stage 1 is divided into 2 groups which consist of 12 engines each. Each group format is a single round robin. There is no opening book in use here, so the engines are on their own from move 1. The top 6 from each group will move on to Stage 2, while the rest are out of TCEC for the current Season.

Stage 2
Stage 2 consists of the 12 engines that qualified from Stage 1. It is a double round robin. The top 6 move on to Stage 3 while the rest are out of TCEC for the current Season.

Stage 3
Stage 3 consists of the 6 engines that qualified from Stage 2. The format for Stage 3 is a hexa round robin (x 6) so that each engine will play both sides of the same opening against each other, three times. After Stage 3 has finished, the top 2 engines will meet in a Superfinal of 100 games.

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.

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.

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.

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 all 20 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 can be adjusted, with advice from each of the engine programmers. Basically it defines the minimum depth for work to be split between threads. If no instructions are given from the programmer, the default value will be used.

Main Hash Size
Each engine is allowed to use up to 32768 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.

Own Opening Book
All opening books shipped with the engines are removed and/or disabled.

Endgame Tablebases
For Season 8, tablebases that are available for the engines are: 5-men Syzygy, 5-men Nalimov and 5-men Gaviota (cp2), depending on which each specific engine can use. For some engines specifying more than one type is possible, but here only one is allowed. Nalimov is preferred. They are all hosted in RAM through a RAM-drive. 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.

Tablebase Cache
For Season 8, each engine is configured with a tablebase cache of 32 MB. This is really irrelevant anyway since they are all hosted in RAM.

Ponder / Permanent Brain
Basically this means that the engines can think during their opponents turn. It is not allowed so it has been disabled because of performance limitations with ony 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 adjusted in any way, except that “keep hash tables” or similar is usually enabled.

Season 8 TCEC Server
CPUs: 2 x 10 core Intel Xeon E5-2650v3 @ 2600 MHz
Motherboard: Supermicro X10DRL-i
RAM: 128 GB Samsung DDR4 Reg/ECC
SSD: Kingston 64 GB
Chassis: Supermicro
OS: Windows Server 2012 R2

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

Who is the reigning TCEC Grand Champion?
Komodo defeated Stockfish in the Superfinal of Season 7, so Komodo 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 server by 1 minute. 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.

Chessdom is dedicated to professional and independent coverage of chess news and events from all over the globe! Join us for live chess games, interviews, video and photo reports, and social media reactions. Follow the development of the strongest chess software, which affects all chess today, via the Top Chess Engine Championship with its 24/7 live broadcast with chat.

Copyright © 2007-2022

To Top