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New version chess engines: CalvinChess 6.1.0 JA

on


Calvin Chess - java chess engine
Author:Dan Kelsey

v.6.1.0:
Calvin 6.1.0 comes with a bigger and better neural network, and many small tweaks to search.

Tests against the previous release suggest a strength increase of around 70 elo LTC / 80 elo STC:

LTC (40+0.4): Elo   | 70.58 +- 7.31
STC (8+0.08): Elo   | 79.61 +- 7.42

Last release I predicted that Calvin 6.0.0 would break 3600 CCRL Blitz, completely underestimating the elo compression at the top of the rating lists. For this release I will make exactly the same mistake all over again, and claim that Calvin should now be around 3600 CCRL Blitz 😄

🔍 Search
Complexity LMR (#357)
Prior countermove bonus (#333)
NMP verification search (#323)
Hindsight LMR extension (#351)
Guard recaptures in Q-search (#320)
Scale futility margin based on move count (#336)
Allow history pruning in PV nodes (#319)
Increase LMR if previous node failed high (#349)
Reduce LMR if node was ever a PV node (#329)
No LMR for good noisies (#314)
Allow LMR for good noisies when !ttpv (#358)
Stop allowing noisy killers (#322)
Return fail medium for Q-search fail high (#337)
Reduce aspiration window widening factor (#334)
Decrease correction history scale (#316)
Add conthist to search history score (#318)
SPSA tunes (#325, #356)
⚖️ Evaluation
New net, add feature factoriser (#341)
New net, 4 -> 6 input buckets (#345)
New net, 6 -> 8 input buckets (#346)
⚡ Performance
Use SIMD for accumulator copies (#332)
Screlu speedup (#326)
Repetition detection speedup (#327)
Fused accumulator refreshes (#353)
How to run
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-6.1.0.jar

For CCRL testers who use ChessGUI, please also download the calvin-wrapper.jar file and place it in the same folder as the calvin jar. When loading Calvin in ChessGUI, pass this file instead of the engine jar. This wrapper allows you to run Calvin without passing in the required JVM args (which ChessGUI does not support).

Jim Ablett compiles:

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