Stockfish's High Evaluation before Mate Score Announced...

[Steve Maughan]

When Stockfish is close to a mate announcement its score starts to climb high. The "score" on a pawn scale can reach +50 or even +100 pawns for the side which is ahead.

My question is...

At a high level what is driving the score so high? It can't be material - there are only ~40 pawns worth of material on the board. It must be some positional terms. Yet I find it hard to believe positional terms could climb so high.

Anyone with a high level explanation?

Thanks - Steve

[D Sceviour]

When Stockfish is close to a mate announcement its score starts to climb high. The "score" on a pawn scale can reach +50 or even +100 pawns for the side which is ahead.

My question is...

At a high level what is driving the score so high? It can't be material - there are only ~40 pawns worth of material on the board. It must be some positional terms. Yet I find it hard to believe positional terms could climb so high.

Anyone with a high level explanation?

Thanks - Steve

Stockfish scores queen contact safety very high. Queen contact is very dangerous.

[mkchan]

Pretty sure it's their king safety evaluation, not so sure if it's only due to queen contact check. From their code i can see some huge multipliers that could easily cause this(also their phased evaluation of the king safety)

[velmarin]

Make position in console Stockfish.
Type "eval".

[elcabesa]

Stockfish use big values to encode checkmate or won endgame. So when the search is near a checkmate or won endgame the search report very high values

[syzygy]

At a high level what is driving the score so high?

Those very high scores that you see are probably fail-highs. So they do not actually correspond to the evaluation score of the node at the end of the PV.

[Eelco de Groot]

At a high level what is driving the score so high?

Those very high scores that you see are probably fail-highs. So they do not actually correspond to the evaluation score of the node at the end of the PV.

I'm not sure but I think actual values, not Fail Highs I see are up to about 128. And this depends on PawnValueEg because of conversion of internal score to pawns

Eval scores that are not mate (Mate is only scored by search when in check but no moves) have to remain at least below below mate at maximum horizon = VALUE_MATE adjusted for maximum depth = VALUE_MATE_IN_MAX_PLY = VALUE_MATE - 2 * MAX_PLY = 32000 - 2* 128 = 31744

divided by PawnValueEg = 248 gives 128

Here is a sample output with high scores:

[D]4k3/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQ -


30 535:49 +M18 1.e3 g6 2.Qg4 a5 3.Nc3 e6 4.Qd4 a4 5.Qxa4 g5 6.Qa8+ Ke7 7.Qxb7 Kd8 8.Qb8+ Ke7 9.Qxc7 g4 10.Qc5+ Ke8 11.Qd6 f5 12.Bb5 Kf7 13.Qxd7+ Kf6 14.Qxh7 (577.606.622.382) 17966
30 535:49 +M18 1.d4 h6 2.Qd3 f6 3.Qc4 e6 4.Qxc7 a6 5.Qxb7 Ke7 6.Nc3 g5 7.Qxa6 Kd8 8.Qd6 f5 9.Qb8+ Ke7 10.Qa7 g4 11.Bxh6 f4 12.O-O-O g3 13.fxg3 fxg3 14.hxg3 (577.606.622.382) 17966
30 535:49 +M19 1.e4 g6 2.Qf3 c6 3.Qc3 d6 4.Qh8+ Kd7 5.Qxh7 f6 6.Qxg6 a5 7.Qf5+ Kc7 8.Qxa5+ Kd7 9.Qa8 Kc7 10.Qe8 e5 11.Qe7+ Kb6 12.Qxd6 Ka7 13.Qxf6 Kb8 14.d4 (577.606.622.382) 17966
30 535:49 +M19 1.Nc3 g6 2.e3 c6 3.Qg4 a6 4.Qg3 d6 5.Qh3 Kd8 6.Qxh7 f6 7.Qg8+ Kc7 8.Qxg6 Kd7 9.Qf7 f5 10.Qxf5+ Kc7 11.Qe6 Kd8 12.Nf3 Kc7 13.Qxe7+ Kb6 14.Qxd6 (577.606.622.382) 17966
30 535:49 +M20 1.b3 g6 2.e3 f5 3.Qf3 c6 4.Qf4 d6 5.Qh6 Kd7 6.Qxh7 g5 7.Qxf5+ Kc7 8.Qxg5 Kd7 9.Qg4+ Ke8 10.Qg8+ Kd7 11.Qf7 a5 12.Ba3 a4 13.Bd3 c5 14.Bf5+ (577.606.622.382) 17966
29 535:49 +128.31 1.Nf3 b6 2.d4 c5 3.e3 c4 4.Bxc4 f6 5.Qd3 Kd8 6.Qxh7 Kc7 7.Qxg7 b5 8.Bxb5 a6 9.Bxa6 Kb6 10.Qxe7 Kxa6 11.Qxd7 Kb6 12.Qd6+ Ka7 13.Qxf6 Kb7 14.Qg7+ (577.606.622.382) 17966
29 535:49 +75.70 1.Nh3 g6 2.e3 b5 3.Qg4 Kd8 4.Qf3 c6 5.Qxf7 a6 6.Ng5 h6 7.Qf8+ Kc7 8.Qxh6 c5 9.Qxg6 c4 10.Qxa6 e6 11.Nxe6+ dxe6 12.Qxe6 Kb7 13.Qd6 Ka7 14.Qc7+ (577.606.622.382) 17966
29 535:49 +46.58 1.c4 e5 2.Qb3 c6 3.Qxb7 Ke7 4.Qxa7 f5 5.Qc7 e4 6.Qe5+ Kd8 7.Qxg7 Kc8 8.Qg8+ Kc7 9.Qxh7 e3 10.dxe3 f4 11.exf4 Kd6 12.Nc3 Kc7 13.Qf7 Kd8 14.Qh5 (577.606.622.382) 17966
29 535:49 +42.25 1.c3 a5 2.Qa4 e5 3.Qxa5 b6 4.Qa7 e4 5.Qxc7 e3 6.fxe3 Ke7 7.Qxb6 h6 8.Qc7 h5 9.Qe5+ Kf8 10.Qb8+ Ke7 11.Qc7 h4 12.Nf3 f6 13.Nxh4 Ke6 14.Qc4+ (577.606.622.382) 17966
29 535:49 +42.02 1.h3 g6 2.e3 f6 3.Qg4 Kd8 4.Bd3 d5 5.Qh4 d4 6.Qxd4+ Kc8 7.Qxa7 c6 8.Qa8+ Kc7 9.Qe8 e5 10.Qe7+ Kc8 11.Qxf6 e4 12.Bxe4 Kc7 13.Qe7+ Kc8 14.Qd6 (577.606.622.382) 17966
29 535:49 +41.91 1.a3 h5 2.e3 g6 3.Qf3 c6 4.Qf4 d6 5.Qd4 Kd7 6.Qxa7 Kc8 7.Qa8+ Kc7 8.Qe8 e5 9.Qxf7+ Kb6 10.Qxg6 d5 11.Qxh5 e4 12.Qe5 Ka7 13.Qe7 Ka8 14.Qf8+ (577.606.622.382) 17966
29 535:49 +41.11 1.d3 g6 2.e3 h5 3.Qf3 c6 4.Qf4 d6 5.Qh6 b5 6.Qg7 f6 7.Qxg6+ Kd8 8.Qxh5 b4 9.Qa5+ Ke8 10.Qxb4 a5 11.Qxa5 c5 12.Qa7 e6 13.Nc3 Kf8 14.Qb6 (577.606.622.382) 17966