Dev Builds » 20260517-1844

Use this dev build

NCM plays each Stockfish dev build 20,000 times against Stockfish 15. This yields an approximate Elo difference and establishes confidence in the strength of the dev builds.

Summary

Host Duration Avg Base NPS Games WLD Standard Elo Ptnml(0-2) Gamepair Elo
ncm-dbt-01 06:43:50 581356 4000 1792 329 1879 +133.24 ± 4.42 0 22 527 1417 34 +311.41 ± 14.81
ncm-dbt-02 06:43:17 584888 4016 1810 334 1872 +133.96 ± 4.38 1 24 508 1448 27 +316.88 ± 15.11
ncm-dbt-03 06:43:35 585941 3998 1807 314 1877 +136.34 ± 4.53 0 23 510 1416 50 +316.69 ± 15.07
ncm-dbt-04 06:42:28 567305 3996 1796 325 1875 +134.19 ± 4.37 0 21 516 1430 31 +315.87 ± 14.97
ncm-dbt-05 06:44:24 580910 3990 1773 320 1897 +132.61 ± 4.37 0 18 537 1409 31 +310.2 ± 14.65
20000 8978 1622 9400 +134.07 ± 1.97 1 108 2598 7120 173 +314.2 ± 6.66

Test Detail

ID Host Base NPS Games WLD Standard Elo Ptnml(0-2) Gamepair Elo CLI PGN
469974 ncm-dbt-02 584748 16 7 1 8 +136.89 ± 61.78 0 0 2 6 0 +337.87 ± 515.83
469973 ncm-dbt-05 580240 490 218 44 228 +128.99 ± 12.57 0 4 65 174 2 +302.73 ± 42.71
469972 ncm-dbt-01 580240 500 224 37 239 +136.56 ± 12.79 0 5 57 184 4 +324.17 ± 45.77
469971 ncm-dbt-04 567363 496 220 39 237 +132.91 ± 12.57 0 3 65 176 4 +310.85 ± 42.67
469970 ncm-dbt-03 584832 498 224 41 233 +133.93 ± 12.51 0 1 70 172 6 +308.83 ± 40.78
469969 ncm-dbt-02 586139 500 232 36 232 +143.89 ± 12.09 0 1 58 185 6 +346.12 ± 45.18
469968 ncm-dbt-05 578177 500 232 27 241 +151.34 ± 11.22 0 0 50 195 5 +381.69 ± 48.77
469967 ncm-dbt-04 568395 500 219 37 244 +132.54 ± 12.52 0 4 63 180 3 +312.48 ± 43.44
469966 ncm-dbt-01 577684 500 223 36 241 +136.56 ± 12.98 0 3 64 176 7 +315.35 ± 43.03
469965 ncm-dbt-03 585759 500 221 42 237 +130.14 ± 12.78 0 3 70 172 5 +298.62 ± 41.01
469964 ncm-dbt-02 587622 500 222 53 225 +122.24 ± 12.76 0 3 79 164 4 +275.45 ± 38.39
469963 ncm-dbt-05 583572 500 227 42 231 +134.95 ± 13.03 0 3 66 174 7 +309.64 ± 42.33
469962 ncm-dbt-01 580365 500 230 53 217 +128.55 ± 13.01 0 3 73 168 6 +290.66 ± 40.08
469961 ncm-dbt-04 567799 500 226 41 233 +134.95 ± 12.44 0 3 63 180 4 +318.25 ± 43.39
469960 ncm-dbt-03 589283 500 231 31 238 +147.19 ± 12.57 0 2 54 186 8 +352.8 ± 47.05
469959 ncm-dbt-02 586181 500 225 36 239 +138.18 ± 12.73 0 4 58 183 5 +327.18 ± 45.37
469958 ncm-dbt-05 578877 500 214 41 245 +125.38 ± 12.51 0 4 71 173 2 +290.66 ± 40.76
469957 ncm-dbt-04 567205 500 231 40 229 +139.81 ± 12.26 0 2 60 183 5 +333.32 ± 44.47
469956 ncm-dbt-01 578054 500 218 40 242 +129.35 ± 12.61 0 3 70 173 4 +298.62 ± 41.01
469955 ncm-dbt-03 586689 500 223 36 241 +136.56 ± 12.98 0 3 64 176 7 +315.35 ± 43.03
469954 ncm-dbt-02 582694 500 229 44 227 +134.95 ± 11.61 0 3 59 188 0 +330.23 ± 44.94
469953 ncm-dbt-05 582318 500 226 40 234 +135.76 ± 12.81 0 2 67 174 7 +312.48 ± 41.9
469952 ncm-dbt-03 585379 500 228 39 233 +138.18 ± 13.32 0 5 58 180 7 +321.19 ± 45.36
469951 ncm-dbt-04 565587 500 226 43 231 +133.34 ± 12.49 0 2 68 175 5 +309.64 ± 41.56
469950 ncm-dbt-01 582068 500 229 38 233 +139.81 ± 11.62 0 2 57 189 2 +342.85 ± 45.71
469949 ncm-dbt-02 583698 500 229 43 228 +135.76 ± 11.58 0 1 64 183 2 +327.18 ± 42.83
469556 ncm-dbt-03 584495 500 230 45 225 +134.95 ± 13.03 0 3 66 174 7 +309.64 ± 42.33
469555 ncm-dbt-01 583279 500 222 44 234 +129.35 ± 12.61 0 3 70 173 4 +298.62 ± 41.01
469554 ncm-dbt-05 579001 500 206 38 256 +121.45 ± 12.4 0 3 78 167 2 +277.93 ± 38.66
469553 ncm-dbt-04 567522 500 219 36 245 +133.34 ± 11.88 0 0 71 175 4 +312.47 ± 40.3
469552 ncm-dbt-02 585970 500 221 41 238 +130.94 ± 13.14 1 4 62 180 3 +309.64 ± 43.82
469551 ncm-dbt-03 584832 500 224 42 234 +132.54 ± 12.52 0 3 66 177 4 +309.64 ± 42.33
469550 ncm-dbt-04 568434 500 226 59 215 +120.67 ± 12.6 0 5 74 170 1 +277.93 ± 39.92
469549 ncm-dbt-05 581693 500 226 41 233 +134.95 ± 12.04 0 0 70 175 5 +315.34 ± 40.62
469548 ncm-dbt-01 583782 500 224 43 233 +131.74 ± 12.74 0 2 71 171 6 +301.33 ± 40.6
469547 ncm-dbt-02 581527 500 231 42 227 +138.18 ± 12.33 0 5 53 190 2 +336.46 ± 47.52
469546 ncm-dbt-04 566138 500 229 30 241 +146.36 ± 11.96 0 2 52 191 5 +359.68 ± 48.01
469545 ncm-dbt-03 586266 500 226 38 236 +137.37 ± 12.76 0 3 62 179 6 +321.19 ± 43.77
469544 ncm-dbt-01 585379 500 222 38 240 +134.15 ± 11.43 0 1 65 183 1 +324.17 ± 42.47
469543 ncm-dbt-05 583405 500 224 47 229 +128.55 ± 11.83 0 2 70 177 1 +304.07 ± 40.91
469542 ncm-dbt-02 585421 500 214 38 248 +127.76 ± 12.84 0 3 73 169 5 +290.66 ± 40.08

Commit

Commit ID 1cebdafc1473484f47d11786e734983d47edab14
Author Robert Nurnberg @ elitebook
Date 2026-05-17 18:44:44 UTC
Help aborted searches remember mate scores This patch improves mate finding results by protecting mate scores from being forgotten in a later iteration. This applies especially to aborted searches, but also to completed iterations in e.g. `go depth` scenarios. The only visible change to the user is the final UCI info line. The case of TB wins/losses was excluded from this patch on purpose. The reason is that in some corner cases related to rounding in some DTZ Syzygy EGTBs, later searches may turn a TB loss into a draw, for example. See #5175 and the example ``` info depth 5 seldepth 5 multipv 1 score cp -20000 nodes 122 nps 8714 hashfull 0 tbhits 26 time 14 pv h1b1 a7b6 f6e5 b6b1 e5f4 c8c3 f4g5 d7h7 g5f4 b1f5 f4f5 c3e5 f5g6 e5f4 g6h7 f4g5 h7h8 b8c7 h8h7 c7d6 h7h8 d6e5 h8h7 e5f6 h7h8 g5g7 info depth 6 seldepth 9 multipv 1 score cp 0 nodes 255 nps 18214 hashfull 0 tbhits 26 time 14 pv h1h2 d7d6 f6g5 a7e7 ``` from #5414. Matetrack for patch: ``` Using ./stockfish on matetrack.epd with --nodes 1000000 Engine ID: Stockfish dev-20260510-dbbc3ed1 Total FENs: 6554 Found mates: 3054 Best mates: 2224 ``` This is slightly more/equal compared to master (3040 and 2224), see https://github.com/vondele/matetrack/blob/faf7cf3be95ab7dfdcde6e035de28a30887cd8a5/matetrack1000000.csv#L4368. Passed STC non-reg: LLR: 2.96 (-2.94,2.94) <-1.75,0.25> Total: 108224 W: 27565 L: 27429 D: 53230 Ptnml(0-2): 212, 11755, 30064, 11847, 234 https://tests.stockfishchess.org/tests/view/6a00899e9392f0c31721406c closes https://github.com/official-stockfish/Stockfish/pull/6816 No functional change
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