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 PR updates the internal WDL model, using data from 2.5M games played by SF-dev (3c62ad7).
Note that the normalizing constant has increased from 329 to 368.
Changes to the fitting procedure:
* the value for --materialMin was increased from 10 to 17: including data with less material leads to less accuracy for larger material count values
* the data was filtered to only include single thread LTC games at 60+0.6
* the data was filtered to only include games from master against patches that are (approximatively) within 5 nElo of master
For more information and plots of the model see PR#5309
closes https://github.com/official-stockfish/Stockfish/pull/5309
No functional change
This PR proposes to change the parameter dependence of Stockfish's
internal WDL model from full move counter to material count. In addition
it ensures that an evaluation of 100 centipawns always corresponds to a
50% win probability at fishtest LTC, whereas for master this holds only
at move number 32. See also
https://github.com/official-stockfish/Stockfish/pull/4920 and the
discussion therein.
The new model was fitted based on about 340M positions extracted from
5.6M fishtest LTC games from the last three weeks, involving SF versions
from e67cc979fd (SF 16.1) to current
master.
The involved commands are for
[WDL_model](https://github.com/official-stockfish/WDL_model) are:
```
./updateWDL.sh --firstrev e67cc979fd
python scoreWDL.py updateWDL.json --plot save --pgnName update_material.png --momType "material" --momTarget 58 --materialMin 10 --modelFitting optimizeProbability
```
The anchor `58` for the material count value was chosen to be as close
as possible to the observed average material count of fishtest LTC games
at move 32 (`43`), while not changing the value of
`NormalizeToPawnValue` compared to the move-based WDL model by more than
1.
The patch only affects the displayed cp and wdl values.
closes https://github.com/official-stockfish/Stockfish/pull/5121
No functional change
Based on 130M positions from 2.1M games.
```
Look recursively in directory pgns for games from SPRT tests using books
matching "UHO_4060_v..epd|UHO_Lichess_4852_v1.epd" for SF revisions
between 8e75548f2a (from 2024-02-17
17:11:46 +0100) and HEAD (from 2024-02-17 17:13:07 +0100). Based on
127920843 positions from 2109240 games, NormalizeToPawnValue should
change from 345 to 356.
```
The patch only affects the UCI-reported cp and wdl values.
closes https://github.com/official-stockfish/Stockfish/pull/5070
No functional change
Update the internal WDL model. After the dual net merge, the internal
evaluations have drifted upwards a bit. With this PR
`NormalizeToPawnValue` changes from `328` to `345`.
The new model was fitted based on about 200M positions extracted from
3.4M fishtest LTC games from the last two weeks, involving SF versions
from 6deb88728f to current master.
Apart from the WDL model parameter update, this PR implements the
following changes:
WDL Model:
- an incorrect 8-move shift in master's WDL model has been fixed
- the polynomials `p_a` and `p_b` are fitted over the move range [8, 120]
- the coefficients for `p_a` and `p_b` are optimized by maximizing the
probability of predicting the observed outcome (credits to @vondele)
SF code:
- for wdl values, move will be clamped to `max(8, min(120, move))`
- no longer clamp the internal eval to [-4000,4000]
- compute `NormalizeToPawnValue` with `round`, not `trunc`
The PR only affects displayed `cp` and `wdl` values.
closes https://github.com/official-stockfish/Stockfish/pull/5002
No functional change
