Arasan 25.0

[jdart]

Arasan 25.0 is available from https://www.arasanchess.org.

Changes in Arasan 25.0:
1) Use a single "Book variety" option to control move selection from the book
2) Some changes to book move selection logic
3) Fix Intel oneAPI compiler support. Add support for CSSPGO with Intel/clang.
4) Fixes/updates to selfplay utility. Support output in the format used by bullet.
5) Add SyzygyUse50MoveRule and SyzygyProbeDepth options for CECP
6) Make NNUE usage non-optional. Fail on startup if network cannot be loaded.
7) arasan.rc is no longer loaded by the engine, by default. Auto-loading (the
prior behavior) can be enabled via the -a command-line option, or use -r to
select a specific file.
8) Make eval command evaluate current position, like Stockfish
9) Change SyzygyTbPath option to SyzygyPath, for conformity to Stockfish
and most other engines
10) New network architecture and network
11) Changes to history score computation
12) Use capture history for move ordering
13) Implement a parameter tuning framework for search parameters, tune some
using Lakas (https://github.com/jdart1/Lakas)
14) Changes to static null pruning, adjust margins
15) Windows GUI sources are now included in the repo
16) GUI can set some options formerly only settable via arasan.rc

There is also an update to the Arasan test suite, available here: https://arasanchess.org/testsuite.shtml.

Test results of version 25.0 against version 24.2, tc 1:0+0.8, 512MB, 8moves_v3.pgn book:

Elo: 19.13 +/- 6.86, nElo: 42.52 +/- 15.23
LOS: 100.00 %, DrawRatio: 79.50 %
Games: 2000, Wins: 260, Losses: 150, Draws: 1590, Points: 1055.0 (52.75 %)

[Graham Banks]

Thanks, Jon.

[AndrewGrant]

Congrats on the release, Jon.

I have the following docker file for building Arasan at Chess.com's CCC. The script used to do a profiled build, but at some point those stopped working. However, trying today, they seem to work.

Code: Select all

# Clone and build from master
RUN git clone https://github.com/jdart1/arasan-chess && \
    cd arasan-chess && \
    git submodule update --init --recursive && \
    cd src && \
    make -j CC=clang BUILD_TYPE=avx2               <---- I can add "profiled" here?

# Copy the init file and the Networks where they are expected
RUN cp arasan-chess/network/* arasan-chess/bin

If there is anything else to be done to create a stronger build, please let me know. Perhaps some way to ensure march=native? Note that the CCC machine is a Ryzen with POOR BMI2 support. So while those flags are helpful, the use of PEXT/PDEP is problematic.

[jdart]

If there is anything else to be done to create a stronger build, please let me know. Perhaps some way to ensure march=native? Note that the CCC machine is a Ryzen with POOR BMI2 support. So while those flags are helpful, the use of PEXT/PDEP is problematic.

Your build flags look fine. You can add "profiled" to do a PGO build. However, my experience is that any performance gain from PGO is quite minor.

[darmar]

Arasan accumulates hash with every move during the game.

[jdart]

Arasan accumulates hash with every move during the game.

Any more details on this: which platform, how are observing this? The hash table is allocated once at startup, and re-allocated if the size is changed. The engine will use more of the hash table as it progresses through the game, but the table size should not increase.

[JohnW]

Anyone else getting a virus warning? I get Gen:Variant.Lazy.205897

[tmokonen]

Anyone else getting a virus warning? I get Gen:Variant.Lazy.205897

Probably spurious BS.

https://www.virustotal.com/gui/file/095 ... 4b8b0a926a
https://www.virustotal.com/gui/file/525 ... 90cffa7beb
https://www.virustotal.com/gui/file/1f3 ... b527622c5d

[Vinvin]

There is also an update to the Arasan test suite, available here: https://arasanchess.org/testsuite.shtml.

Hi, John !
There still a "2023" in the "2024" file : "arasan2023.37".

Congratulation for the new engine !

[jdart]

There is also an update to the Arasan test suite, available here: https://arasanchess.org/testsuite.shtml.

Hi, John !
There still a "2023" in the "2024" file : "arasan2023.37".

Thanks, will correct.