Hello!

You may remember me from such posts as "Dead Draw Detector 2.0".
In a nutshell, a solution to the problem of deciding whether a chess game should be drawn after a timeout.

I have run the tool over the entire database of Lichess (standard rated). Remarkably, the tool could identify ALL unwinnable positions without missing a single one (for all others there exists a helpmate sequence).

Here you can find all the unfairly classified (with respect to the FIDE rules) games in Lichess (up to May 2021):
elrubiongamma.ddns.net/chess-unwinnability-analyzer/games.html

I hope you enjoy the results, some positions are very interesting!

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By the way, the analysis took about 65 hours of CPU time (325 μs per position on average).
Find more information about the performance here:
elrubiongamma.ddns.net/chess-unwinnability-analyzer/about.html#results

Our algorithm can handle about 3000 positions per second (7000 in "quick mode"), whereas the estimated flow of Lichess games (that require this analysis) nowadays is of 12 games per second. 🙂

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Cool works.
There are some nice positions.
It includes many games (like below) where one player thought he was checkmated although he was a single move away from winning which would have make for a fun ending. I guess they didn't find the remaining legal moves.

lichess.org/aO4zIDAW#69

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Thanks @Kigal for your message!

Yeah, there is usually two types of positions: (i) the tree of moves is small and never leads to a victory for the intended winner and (ii) the position is blocked and players cannot make progress (the typical pawn wall).

However, there is also more complex positions like the following. Which is not really "blocked", but if Black captures on g2 to unlock the position, then White is in stalemate.

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#4 This game is rather interesting, with the fact that white has absolutely NO WAY of winning

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@Nyghtguard That's right! There is no way of winning for Black either!

Check those out, please!

chess.stackexchange.com/questions/22555/is-the-dead-position-problem-solvable/22764#22764

Hi @Sarg0n !

Yes, all those positions are handled by the tool.
You can try the tool yourself here:
elrubiongamma.ddns.net/chess-unwinnability-analyzer

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Noice! :) I will try, thx.

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