19

I reached this position as Black:

[Title "Black to move"]
[FEN "8/8/8/3q4/6kp/7R/6P1/6K1 b - - 3 46"]

And I felt that I cannot make any progress and so it feels like a draw. However, Stockfish evaluates it as −5.1, though it also seems to be unable to get anywhere. So is this actually a draw, or is there some obscure line of play that Stockfish has missed as well?

1
  • A similar position featured in a MathOverflow answer on whether "high-level proofs" about chess positions are possible. A proof is outlined in that answer, hopefully enough to explain why it is a fortress.
    – Kostya_I
    Mar 15 at 16:42
28

This is a fortress and a draw.

The black king can't advance as the rook, shuffling between h3 and f3, prevents it. The only way to break the fortress is to trade the queen for the rook and pawn, but the resulting endgame is still a draw.

1
22

This position is a standard classical fortress. There is no way the Black color can go through as long as White just shuffle pieces, wait and do nothing silly.

Stockfish is a computer algorithm, it has no intelligence. It doesn't know it's a draw unless it searches for all the possibilities, but it's practically impossible.

Connect to a 6-piece tablebase, and you will instantly see it's a draw. Or run Stockfish with a tablebase, instant draw.

0

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