Endgame Tablebases

7-piece Tablebase Claims

The 2013 ICCF Congress in Kraków, decided that for all tournaments started after 01/01/2014, players will be allowed to claim a win or draw if the position can be resolved in a 6 piece tablebase position. Furthermore the 2019 ICCF Congress in Vilnius, decided that these claims be extended to 7 piece tablebases.

ICCF have an agreement with LiChess whom will provide ICCF Tournament Directors free access to the 7 piece Syzygy tablebases. 

What are endgame tablebases?

Endgame tablebases are computer databases of chess endings with precise calculations for optimal play in any position, provided the number of pieces on the board does not exceed a certain limit.

Simply put, the program determines if the position leads to a draw or can be won by either side - with 100% certainty. If the game can be won, the path with the least number of moves until the end of this variation is shown, given that both players make the best moves possible. If the losing player makes a suboptimal move, he will lose sooner, and the program will display the new optimal path.

Syzygy tablebases

Syzygy tablebases allow perfect play with up to 7 pieces, both with and without the fifty-move drawing rule, i.e., they allow winning all won positions and bringing all drawn positions over the fifty-move line.

Free access can be gained via:


How to make a claim?

Players may only claim positions resolved by 7-piece tablebases.

The procedure is similar to other ICCF claims, players may use the dropdown menu in the game page to either "Claim a win" or "Claim a draw". They must state in the claim form that they are claiming based on endgame tablebases. They may claim based on current board position or indicate a proposed move and claim based on that position. The proposed move must not be played on the board otherwise the player will have to wait until the next turn before filing the claim. Simply indicate the proposed move in the claim form.

Please note that you can only claim when it is your turn to move.

Once the claim is submitted, the server will evaluate the position and set the result if the claim is correct; this process is entirely automatic and does not require the TD to intervene.

Claims in team matches are now submitted directly to the server, it is no longer necessary to submit claims via team captains.

last updated Wednesday, May 15, 2024

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