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New version chess engines: CalvinChess 5.0.2



Calvin Chess - java chess engine
Author:Dan Kelsey

v.5.0.2:
This is another bugfix release to address some crashes and other issues that arose during testing of 5.0.0 and 5.0.1.

The main bugfix prevents Calvin crashing during very long games, where the number of ply exceeds Calvin's maximum ply of 256. Other fixes are to disable pretty print for tournament runners/GUIs (it is now disabled as soon as receiving a 'uci' command), and finally to always return a random legal move as last resort when encountering a crash.

It also includes some unrelated strength-gaining changes that I merged in the past weeks.

🐛 Don't increment ply when applying UCI moves (#225)
🐛 Disable pretty print for tournament runners (#226)
🔍 Apply futility reductions to 'bad noisies' (#224)
🔍 Overwrite TT entries where depth >= ttDepth - 4 (#229)
Tests suggest the bugfixes and search patches amount to a gain of 25 elo (LTC):

Score of Calvin DEV vs Calvin: 774 - 485 - 2741  [0.536] 4000
...      Calvin DEV playing White: 660 - 47 - 1293  [0.653] 2000
...      Calvin DEV playing Black: 114 - 438 - 1448  [0.419] 2000
...      White vs Black: 1098 - 161 - 2741  [0.617] 4000
Elo difference: 25.1 +/- 6.0, LOS: 100.0 %, DrawRatio: 68.5 %
Thank you to testers for pointing out these crashes + bugs!

How to run
Calvin is available for download as a Java jar file, or as a standalone Windows executable.

To run the jar file, you will need to enable the Vector API package which Calvin uses for SIMD, via this command:

java --add-modules jdk.incubator.vector -jar path/to/calvin-chess-engine-5.0.1.jar



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