Current State of EGTB support/probing and such

Discussion of chess software programming and technical issues.

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Michel
Posts: 2272
Joined: Mon Sep 29, 2008 1:50 am

Re: Current State of EGTB support/probing and such

Post by Michel »

Stockfish will flawlessly win it (unless it is a "cursed" win because of the 50-move rule, in which case Stockfish will use a "swindle" mode and most likely still win it), but the scores reported might be drawish because the search cannot yet see the win.
Maybe I am misunderstanding but Stockfish has a "winscore" constant (70 I believe). You could just add that to the scores returned by the search
in case it is a table base win without the DTM score being known.
syzygy
Posts: 5566
Joined: Tue Feb 28, 2012 11:56 pm

Re: Current State of EGTB support/probing and such

Post by syzygy »

Michel wrote:
Stockfish will flawlessly win it (unless it is a "cursed" win because of the 50-move rule, in which case Stockfish will use a "swindle" mode and most likely still win it), but the scores reported might be drawish because the search cannot yet see the win.
Maybe I am misunderstanding but Stockfish has a "winscore" constant (70 I believe). You could just add that to the scores returned by the search
in case it is a table base win without the DTM score being known.
There is a VALUE_KNOWN_WIN constant which is 15000. Simply adding it seems dangerous because of the risk of overflow, but indeed it is possible to display the score adjusted upwards (or downwards) in case the position is known to be won (or lost) but the search does not see it yet. And in case of a known draw the reported score could of course be adjusted to 0. This is probably what I should implement to reduce confusion.

Still it seems interesting to see the actual evaluation by Stockfish, as long as there is also some way to inform the GUI of the TB outcome.