Mate solving test SF19, SF18 and SF11.

[Jouni]

600 longest positions from matetrack (mate in 16 to mate in 126) https://github.com/vondele/matetrack . Found mates in 10 second with 6 cores:

SF11 288
SF18 268
SF19 243

For comparison Huntsman 443.

[Jouni]

Stockfish 19 surprises by solving some classic positions very fast.

[d]3qk3/8/8/8/8/8/PPPPPPPP/RNBQKBNR w KQ - 0 1

Analysis by Stockfish 19:
...
1.e4 Qd6 2.d4 Qg6 3.Qf3 Qf7 4.Bb5+ Ke7 5.Bg5+ Kf8 6.Bh6+ Ke7 7.Qg3 Kd8 8.Qd6+ Kc8 9.Bf4 Qa7 10.Ba6+ Qxa6 11.Qc7#
+- (#11) Depth: 51/24 00:00:15 71308kN

[mysammoore]

As long as there are consistent checks, I would always imagine an HCE engine to out-calc mate lines vs. an NNUE unless the HCE was very slow. Mate lines are far more factual than eval-driven. Honestly the stronger the NNUE the weaker I'd expect it to perform under this test scenario.

[Eelco de Groot]

It is not really sure Stockfish 11 consistently outperforms Stockfish 19 even if you have a large sample like this. (It is still all a bit nondeterministic with 6 threads) The HCE helps of course if it is faster. Stockfish can speedup mate searches (just for testing?) and if I read the commit right, in matetrack.epd testing now does so by making search changes. If you know you are looking for mate you can for instance use a pretty narrow and high search window so everything else falls outside of it. I am not really sure why they are doing it if it is just to test Master. But if you put difficult positions in the epd they use, Stockfish will search some faster now but it is more for very short DTMs if I read that. Some people would like a version where they could set that variable themselves in UCI options perhaps

[Jouni]

Result is no surprise, because SF11 speed is triple to SF19! 10 MNPS vs 3,5 MNPS. Actually Stockfish 19 is best mate finder among top programs.