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@dlbbld dlbbld released this 07 Oct 07:45
· 2 commits to main since this release
22.1.0
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Learn about vigilant mode.

Magic bitboards and faster adjudication

Bishop and rook attack generation now uses magic bitboards, with unchanged move-generation semantics and a measured reduction in legal-move generation time across three machines. Flag-fall and resignation adjudication gain a guarded elementary-material theorem pre-check that avoids search where the result is already proven. The release also adds reproducible performance tooling and hardens the release procedure. No public API is removed or changed.

Notable

  • Magic-bitboard slider attacks. Bishop and rook queries use precomputed occupancy-indexed tables; queen attacks combine them. Independent geometric, differential and perft checks verify correctness. Measured legal-move generation time falls by approximately 17–25% across the reviewed ThinkPad, iMac M3 and IdeaCentre workloads. The tables require 841 KiB of attack entries plus metadata, with a one-time initialization cost. See the verification record for workloads, environments and corrected baselines.
  • Faster adjudication on covered elementary-material positions. Quick and full flag-fall/resignation methods first consult the basic-helpmate-existence theorem. The pre-check excludes KBNvK and opposite-coloured KBBvK, whose retro-illegal counterexamples can pass strict FEN parsing, and defers those classes to the existing analyzers. The standalone quick and full unwinnability analyzers retain their paper-derived algorithms and witness contracts.

Validation and tooling

  • An opt-in JMH profile provides slider microbenchmarks and production workloads without adding JMH to the published library. iMac and Windows procedures preserve machine/JVM details, raw fork results, logs and harness fingerprints.
  • A default-profile corpus lint catches malformed strict PGN file structure before the expensive release suites. Additional proof games pin the chasolver exhaustion challenges, with external oracle coverage.
  • The test-only chesslib comparison dependency is updated to 1.3.7.
  • Release preflight now runs fail-fast gates in cost order: clean working tree, license headers, JavaDoc, then both full regression suites. Release notes are generated from the changelog with paragraphs unwrapped for GitHub rendering.
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