Why doesn’t Stockfish evaluate this fortress as 0.0? I'm going through the 100 endgames you must know book on Chessable and stumbled upon something I don't understand. This position with white to move is described as a draw starting with 1. Kh1. I figured well why wouldn't 1. Kf1 be a draw and I put the exercise into Lichess analyses, which evaluates the position as -2,5, no matter which move white plays.
Why isn't Stockfish able to evaluate this position as 0.0? It says 'depth 64'. Wouldn't it only need to calculate 50 moves to establish that this is a fortress and thereby a draw?
[FEN &quot;8/8/1n6/8/8/5k1p/7P/6K1 w - - 0 1&quot;]
Depth 64 means 64 half moves, it includes moves both by white and black. It isn't close to being able detect draws by means of the 50 move rule (100 plies). Especially since that is only the depth of the deepest line in the search, and to conclude it was certainly a draw, Stockfish would have to look at a huge number of lines that all eventually draw by the 50 move rule.
Endgame draws like this are notoriously difficult for engines, they have no good way to judge &quot;progress&quot; in their calculations. There are some attempts being tried out but they aren't at the level of Stockfish yet.
This is why tablebases were invented -- huge databases of all positions with up to some number of pieces (7 at the moment I think). They give an immediate answer. This is a five-piece position and a Stockfish configured to use tablebases would immediately know it is a draw.