Arasan 22.1

[jdart]

Arasan 22.1 is available from https://www.arasanchess.org.

Changes in Arasan 22.1:
1) Remove potential passer scoring.
2) Tighten validation of hash/killer moves
3) Fix Resign threshold option (CECP mode)
4) Simplify lmp threshold computation. No longer different for PV.
5) Modify formula for lmp count. Do not allow 0 as depth index.
6) Increase razor margin and reduce razoring depth.
7) Fixes to singular search code. Verify hash move before doing a singular search.
8) If singular extension is triggered, do not compute any additional extension, or reduction.
9) Implement bench command. Use bench command for PGO.
10) Update test tools to use pentanomial model for SPRT.
11) MultiPV bug fixes, including a fix for bad ponder move output in MultiPV mode.
12) Fix accept draw logic (CECP mode)
13) Do not update history on fail high of 1st quiet and low depth (idea from Ethereal).
14) Fix possible crash: when iterating through the search threads, ensure any that have
a null "work" pointer are skipped.
15) Allow ProbCut while in check, and restrict recursive Probcut
16) Optimization in seeSign() function
17) Misc. code cleanup

Some test results at 1:0+0.6 vs 22.0:

82 576 1409 803 130
6000 games, score: 52.69%
ELO: 18.72 +-5.3 (95%)
LOS: 100.0%

[Graham Banks]

Thanks, Jon.

[Dann Corbit]

wonderful news. Keep up the good work. I like your engine and your EPD tests

[Alayan]

Congratulations on the new release ! It's nice to see your engine still improving year after year.

13) Do not update history on fail high of 1st quiet and low depth (idea from Ethereal).

Happy to see my idea successful in other engines.

[fjpv]

Hi jdart

Trying to download the Arasan 22.1 Windows installer and I receive a message 404 Error - Page Not Found.

Regards,
fjpv

[jdart]

Trying to download the Arasan 22.1 Windows installer and I receive a message 404 Error - Page Not Found.

Please try again - should be fixed now.

--Jon

[Damir]

Nice improvement Jon. Keep up in doing a good work.

[fjpv]

Trying to download the Arasan 22.1 Windows installer and I receive a message 404 Error - Page Not Found.

Please try again - should be fixed now.

--Jon

Working. Thanks

-- Fernando

[Dann Corbit]

Interesting how Arasan has progressed over the years.

If we think back to the days when Junior or Ruffian or Shredder or Rybka dominated the chess scene, they seemed to dwell in unapproachable light for a time.

But the current Arasan would take all of them, and rub their noses in the dirt.[*]

Shows you the amazing power of sticking to something and continuing to work.

[*]For Shredder, I speak of the old version that dominated the SSDF for a long time. The current version of Shredder has also progressed.

[Dr.Wael Deeb]

Interesting how Arasan has progressed over the years.

If we think back to the days when Junior or Ruffian or Shredder or Rybka dominated the chess scene, they seemed to dwell in unapproachable light for a time.

But the current Arasan would take all of them, and rub their noses in the dirt.[*]

Shows you the amazing power of sticking to something and continuing to work.

[*]For Shredder, I speak of the old version that dominated the SSDF for a long time. The current version of Shredder has also progressed.

I remember the time when Ruffian dominated the computer chess scene ....

It was a magical time for me,I read all the articles,all the interviews and whatever was published then ....

Cheers,
Dr.Deeb