Why is Fritz 16 Grandmaster Playing Weak Endgames?

Question

I am trying to use Fritz 16 to practice endgames. Unfortunately, Grandmaster (Fritz) is playing very poorly. For example, in the diagrammed position, if I play Black, Fritz gives me a quick threefold repetition after 1 Ke4 Nc6 2 Kf5 Na7. But when I play White, Fritz resigns after 1 Ke4 Nc6 2 Kd5 Na5 3 Ke5 Kg7 4 Bd5 Kg6 5 Kd4 Kf6 6 Kc3 Kf5 7 Bh1 Ke5 8 Bg2.

[title "White to move"]
[fen "7k/8/8/2P1n3/8/4KB2/8/8 w - - 0 1"]

1. Ke4 Nc6 2. Kd5 (2. Kf5 Na7) Na5 3. Ke5 Kg7 4. Bd5 Kg6 5. Kd4 Kf6 6. Kc3 Kf5 7. Bh1 Ke5 8. Bg2

Why is Grandmaster (Fritz) playing this ending so poorly? Do I need to change the settings? It doesn't make sense that the engine resigns with Black, but plays a draw by repetition with White.

Any ideas? Are there settings I can change? I have triple checked that I have set the engine to Grandmaster level.

Answer 1

Fritz's 2.Kf5 is a mistake because 2.Kd5 is the only winning move according to the tablebase. Maybe Fritz suffered from the horizon effect (couldn't see far enough ahead) which turned the win into a draw. After that, a draw by repetition doesn't seem unreasonable.

Playing black, Fritz resigns but that's after seven moves, so the "horizon" is now closer, presumably close enough for Fritz to tell it lost (will lose the knight within a couple of moves with no way to stop the pawn).

I don't have Fritz, but from what I can tell "grandmaster" is one of its handicap levels (the strongest, but I'm guessing not as strong as running the engine at full strength). Handicapping an engine is not an exact science so maybe it does play this endgame in a way that's weaker than an actual grandmaster. See if there is any setting to play against the full strength engine. Also I think there is a way of getting Fritz to use a tablebase.

Answer 2

Most engines are weak in certain types of endgame, unless they are provided with an endgame tablebase (EGTB) or sufficient search depth to reliably find the way to the best mate, draw or conversion.

EGTBs tend to be fairly large (eg. about 1GB for the Syzygy 5-man set, and exponentially larger for 6 and 7 man sets) so might not be installed by default.