Update the WDL model

mirror of https://github.com/official-stockfish/Stockfish.git synced 2026-07-23 05:07:14 +00:00

This PR updates the internal WDL model, using data from 2.6M games
played by the revisions since f3bfce3531.
Note that the normalizing constant increases only moderately from 372 to
377.

```
> ./updateWDL.sh --firstrev f3bfce3531
Running: ./updateWDL.sh --firstrev f3bfce3531 --lasttrev HEAD --materialMin 17 --EloDiffMax 5
started at:  Sat 22 Mar 11:02:14 CET 2025
Look recursively in directory pgns for games with max nElo difference 5 using books matching "UHO_Lichess_4852_v..epd" for SF revisions between f3bfce3531 (from 2025-02-28 09:50:59 +0100) and HEAD (from 2025-03-21 11:22:59 +0100).
Based on 138253430 positions from 2579360 games, NormalizeToPawnValue should change from 372 to 377.
ended at:  Sat 22 Mar 11:04:00 CET 2025
```

```
> cat scoreWDL.log
Converting evals with NormalizeData = {'momType': 'material', 'momMin': 17, 'momMax': 78, 'momTarget': 58, 'as': [-37.45051876, 121.19101539, -132.78783573, 420.70576692]}.
Reading eval stats from updateWDL.json.
Retained (W,D,L) = (33794348, 69943262, 34515820) positions.
Saved distribution plot to updateWDLdistro.png.
Fit WDL model based on material.
Initial objective function:  0.3648260131692729
Final objective function:    0.36482338611818094
Optimization terminated successfully.
const int NormalizeToPawnValue = 377;
Corresponding spread = 71;
Corresponding normalized spread = 0.1879431202530567;
Draw rate at 0.0 eval at material 58 = 0.9902694872976331;
Parameters in internal value units:
p_a = ((-13.500 * x / 58 + 40.928) * x / 58 + -36.828) * x / 58 + 386.830
p_b = ((96.534 * x / 58 + -165.791) * x / 58 + 90.897) * x / 58 + 49.296
    constexpr double as[] = {-13.50030198, 40.92780883, -36.82753545, 386.83004070};
    constexpr double bs[] = {96.53354896, -165.79058388, 90.89679019, 49.29561889};
Preparing plots.
Saved graphics to updateWDL.png.
Total elapsed time = 46.92s.
```

Only affects displayed `cp` and `wdl` values.

closes https://github.com/official-stockfish/Stockfish/pull/5939

No functional change

This commit is contained in:

Robert Nurnberg @ elitebook

2025-03-29 11:54:32 +01:00

committed by

Disservin

parent 6028264cb9

commit 4a869f41c6

1 changed files with 2 additions and 2 deletions

									
										src/uci.cpp
									
		+2
		-2
	
												View File
												
				@@ -513,8 +513,8 @@ WinRateParams win_rate_params(const Position& pos) {

				    double m = std::clamp(material, 17, 78) / 58.0;

				    // Return a = p_a(material) and b = p_b(material), see github.com/official-stockfish/WDL_model

				    constexpr double as[] = {-37.45051876, 121.19101539, -132.78783573, 420.70576692};

				    constexpr double bs[] = {90.26261072, -137.26549898, 71.10130540, 51.35259597};

				    constexpr double as[] = {-13.50030198, 40.92780883, -36.82753545, 386.83004070};

				    constexpr double bs[] = {96.53354896, -165.79058388, 90.89679019, 49.29561889};

				    double a = (((as[0] * m + as[1]) * m + as[2]) * m) + as[3];

				    double b = (((bs[0] * m + bs[1]) * m + bs[2]) * m) + bs[3];