Sykora is a chess engine written in Zig that implements the Universal Chess Interface (UCI) protocol. It provides a robust and efficient implementation of chess game logic and UCI communication.Gihub:https://github.com/sb2bg/sykora
Author: Sullivan Bognar Rating Chess Engines Diary CEDR=3356
Sykora is a new engine, and we'll be testing it for the first time, so its performance potential isn't known yet. Keep an eye on our website.
Sykora 4.0.0 what's new?
Sykora 4.0 is a major NNUE and search release.
Added
Added the SYKNNUE8 threat-aware pairwise-MLP evaluator with incremental piece-square and full-threat accumulators, ten mirrored king buckets, and eight material output heads.
Added conservative tactical ProbCut and quiet-move SEE pruning to the accepted search stack.
Added OpenBench workload, deterministic benchmark, and SPSA integration for reproducible distributed search testing.
Changed
Promoted the final v8_t1024_broad_20260724T205147Z SYKNNUE8 network to the embedded default.
Adopted the accepted search defaults LMRScale=134, LMRHistoryScale=95, LMPMoveScale=96, and HistoryMaxBonus=490.
Optimized NNUE threat accumulation, pooling, transposition-table access, and shared search hot paths.
Made the deployment and training pipelines SYKNNUE8-only and added configurable NNUE fine-tuning.
Fixed
Enforced exact fixed-node limits across the main and helper search threads.
Raised the NNUE SIMD compile-time branch quota so optimized Zen 4 worker builds compile reliably with Zig 0.15.2.
Sykora 4.0 measured +158.22 Elo over Sykora 3.1 in a direct 760-game OpenBench SPRT. An architecture-controlled test measured SYKNNUE8 at +141.77 Elo against the matched SYKNNUE7 evaluator.
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