In master for various reasons the given ponder move may get out of sync
with (the second move of) the last PV sent to the GUI:
1. If a ponder move is extracted from the TT despite bestmove leading to
a game ending draw.
2. If a ponder move is extracted from the TT from a fail high/low, since
after the ponder move extraction no new PV is sent to the GUI.
3. If `syzygy_extend_pv()` from within the call to `pv()` changes the PV
after the ponder move has been selected.
4. If the PV roll-back to protect mated-in scores differs in the second
move from the final PV sent to the GUI.
This PR keeps ponder move and the last printed PV in sync.
Fixes#6676.
closes https://github.com/official-stockfish/Stockfish/pull/6679
No functional change
Ever since #5094 master only lets the main thread terminate `go mate`
searches, reverting the earlier improvement #1215.
This PR restores the old logic. So any thread that found a "mate in x"
can now stop the search.
To make this work robustly, we need to guard against inexact mate scores
in the best thread selection. In addition, in contrast to time limits,
the main thread may now not complete a d1 search for a mated-in
position.
In master an aborted d1 search may have a PV beginning with
`Move::none()`, in which case no thread selection is performed. See
#623. We fix this bug here by checking if `lastBestPV` is empty or not.
For interrupted d1 searches we now label mated-in scores as inexact.
While at it, we also simplify the logic for detecting if we can
terminate a go mate x search, using the fact that threads.stop can only
be false if we have a completed iteration with a valid score.
The PR has no effect on game play, but should slightly improve general
mate finding and speed up multi-threaded `go mate` searches.
We also add a corresponding matecheck run to the CI. This only involves
61 mates up to mate-in-2. Test runs with the first 50 or 100 mates from
`mates2000.epd` did at times not finish within 30 minutes on my fork or
in local tests, possibly due to search explosions for some mate-in-3
positions.
closes https://github.com/official-stockfish/Stockfish/pull/6668
No functional change
This PR removes the variable threads.abortedSearch introduced in #4990 and
relies on threads.stop and completedDepth instead.
The logic in master is only guaranteed to work in single threaded search. For
multiple threads, as soon as threads.stop is set, some of the threads may abort
their search, and so their mated-in scores are not reliable.
Compared to master, this patch prevents unproven mated-in scores in these
multi-threaded scenarios:
in game play (when time management is used)
when the uci commands quit or stop are received
when maximum depth is reached
for go mate commands
The patch will change the bestmove in those very rare situations where the bug
occurs in master. This is because bestmove is taken from rootMoves[0].pv[0],
which will now no longer contain unproven mated-in PVs. In that sense the patch
is "functional". But of course, it does not change bench.
While at it, we also fix a bug in master that suppressed PV output for inexact
mated-in scores on receiving threads.stop. In cases where uciScore < score with
score not being a proven loss, and where the new bestmove was different from
the last completed iteration, this led to a bestmove output that did not match
the final PV (which was for an exact score).
Fixes#6293.
Fixes#6626.
closes https://github.com/official-stockfish/Stockfish/pull/6636
No functional change
This PR updates the internal WDL model, using data from 3.1M games played by
the revisions since 44d5467. Note that the normalizing constant increases only
moderately from 377 to 385.
closes https://github.com/official-stockfish/Stockfish/pull/6549
No functional change
This PR allows for time checking within Tablebases::rank_root_moves(). The
principal application for now is syzygy_extend_pv().
In the past, Stockfish suffered some time losses at e.g. TCEC when the HDD with
the DTZ tables was too slow for the chosen move overhead setting, see #5894.
```
> ./fastchess -engine name="patch" cmd=./stockfish.patch -engine name="master" cmd=./stockfish.master -each tc=10+0.1 option.SyzygyPath=/disk1/syzygy/3-4-5-6/WDL:/disk2/syzygy/3-4-5-6/DTZ -draw movenumber=34 movecount=8 score=20 -openings file=UHO_Lichess_4852_v1.epd format=epd -rounds 50 -repeat -concurrency 16
...
Results of patch vs master (10+0.1, 1t, 16MB, UHO_Lichess_4852_v1.epd):
Elo: 59.64 +/- 35.35, nElo: 117.61 +/- 68.10
LOS: 99.96 %, DrawRatio: 56.00 %, PairsRatio: 4.50
Games: 100, Wins: 34, Losses: 17, Draws: 49, Points: 58.5 (58.50 %)
Ptnml(0-2): [0, 4, 28, 15, 3], WL/DD Ratio: 0.87
--------------------------------------------------
Player: master
Timeouts: 19
Crashed: 0
Finished match
```
closes https://github.com/official-stockfish/Stockfish/pull/6422
No functional change
Add runs with --threads 4 to our matetrack CI. These won't be deterministic, of
course. But they may catch early some multithreading bugs in our mate
reporting.
Motivated by #6293 and #6296.
https://github.com/official-stockfish/Stockfish/pull/6297
No functional change.
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
