shakmaty-syzygy

A Rust library to probe Syzygy endgame tablebases, based on shakmaty.

Syzygy tables allow optimal play under the 50-move rule. Tables are available for positions with up to 7 pieces.

Example: Usage

```rust use shakmaty::{CastlingMode, Chess, fen::Fen}; use shakmaty_syzygy::{Tablebase, MaybeRounded, Wdl, Dtz, Syzygy};

let mut tables = Tablebase::new(); tables.add_directory("tables/chess")?;

let pos: Chess = "8/8/8/8/B7/N7/K2k4/8 b - - 0 1" .parse::()? .position(CastlingMode::Standard)?;

let wdl = tables.probewdlafterzeroing(&pos)?; asserteq!(wdl, Wdl::Loss);

let dtz = tables.probe_dtz(&pos)?; assert!(matches!(dtz, MaybeRounded::Rounded(Dtz(-59)))); ```

Example: Command line tool

A command line tool similar to Fathom:

``` $ cargo run --example fathom -- --path tables/chess -- "3qk3/8/8/8/8/8/8/4K3 w - - 0 1" [Event "KvKQ"] [Site ""] [Date "????.??.??"] [Round "-"] [White "Syzygy"] [Black "Syzygy"] [Result "0-1"] [FEN "3qk3/8/8/8/8/8/8/4K3 w - - 0 1"] [Annotator "shakmaty-syzygy"] [DTZ "-16 or -17"]

{ KvKQ with DTZ -16 or -17 } 1. Ke2 Kd7 2. Kd1 Ke6+ 3. Kc1 Qd3 4. Kb2 Qd2+ 5. Ka1 Kd5 6. Kb1 Kc4 7. Ka1 Kb3 8. Kb1 Qd1# { Checkmate } 0-1 ```

Documentation

Read the documentation

Changelog

• 0.18.0
  • Introduce MaybeRounded and AmbiguousWdl, ensuring that DTZ rounding is handled.
  • Add Tablebase::max_pieces().
  • Dtz::before_zeroing() is no longer generic.
  • Dtz::add_plies() now takes u32. Add checked and saturating versions.
  • Fix ProbeError::CorruptedTable should be #[non_exhaustive] when backtrace feature not enabled.
  • Optimize initialization of internal constants, no longer depending on on lazy_static.
• 0.17.0
  • Update shakmaty to 0.20.
• 0.16.1
  • Update shakmaty to 0.19.
• 0.15.0
  • Update shakmaty to 0.18.
• 0.14.0
  • Update shakmaty to 0.17.
  • Fix panic when lead pawns are corrupted.
• 0.13.1
  • Explicit #![forbid(unsafe_code)].
  • Update dependencies.
• 0.13.0
  • Update shakmaty to 0.16.
  • No longer depend on failure. Instead, nightly Rust and the backtrace feature are required to get backtraces for corrupted tables.
  • Validate file size when opening table files.
• 0.12.1
  • Update dependencies.
• 0.12.0
  • Update shakmaty to 0.15.
• 0.11.1
  • Update dependencies.
• 0.11.0
  • Update shakmaty to 0.14.
  • Add reimplementation of Fathom as example.
• 0.10.0
  • Update shakmaty to 0.13.
  • Use FADV_RANDOM on tablebase files.
• 0.9.0
  • Update shakmaty to 0.12.
  • Tablebase::add_directory() now returns the number of added files.
  • Added Tablebase::add_file().
  • ProbeError and Metric are now public. Other previously hidden APIs are no longer exposed.
  • Various refactorings, performance improvements and dependency updates.
• 0.8.1
  • Optimize reading block lengths.
  • More internal refactorings.
  • Add benchmark.
• 0.8.0
  • Update shakmaty to 0.11.x.
  • Add Syzygy::MAX_PIECES.
  • More efficient Tablebase::best_move().
  • Internal refactorings following tablebase rewrite in Cfish.
• 0.7.0
  • Update shakmaty to 0.10.x.
• 0.6.0
  • Update shakmaty to 0.9.x. Minimum Rust version is now 1.27.0.
• 0.5.2
  • Fix Wdl::from_dtz_after_zeroing(Dtz(100)).
• 0.5.1
  • Fix out of bounds panic when probing KPPPPPvK.
  • Fix error when first group in giveaway should have had more than two identical pieces.
  • Only 6 pieces supported in antichess variants. Return SyzygyError::TooManyPieces instead of potential panic.
• 0.5.0
  • More contextual information for errors (table, backtrace, invalid magic header bytes).
  • Update to shakmaty 0.8.x.
  • Provide a target for cargo fuzz. Fix several panics caused by initializing and probing corrupted tables:
  • Panic when reference pawn is missing.
  • Panic when subtable material is not consistent with first file.
  • Integer overflow when reading symlen.
  • Integer overflow when min_symlen or max_symlen are out of bounds.
  • Integer overflow when computing block_length_size.
  • Stack overflow when recursively reading symlen.
• 0.4.5
  • Make better use of positioned-io (cursor, remove RandomAccessFile).
• 0.4.4
  • Remove work around from 0.3.1.
  • Minor internal optimizations and cleanups.
• 0.4.3
  • Fix DTZ off-by-one in some positions when there is mate in 1.
  • Fix DTZ off-by-one in antichess endgames, when there is a threat to force a capture leading to a blessed loss.
  • Add Tablebase::best_move().
• 0.4.2
  • Fix DTZ in en passant positions.
  • Minimum Rust version 1.26.0.
  • Use guaranteed lossless versions from u16 to usize.
  • Provide i128 conversions for Wdl and Dtz.
• 0.4.1
  • Fix debug assertion for Dtz(0).add_plies().
• 0.4.0
  • Update to shakmaty 0.7.x, which has bugfixes with regard to insufficient material.
• 0.3.1
  • Work around compiler bug in release mode.
• 0.3.0
  • Rename Tablebases to Tablebase.
  • Group file extension and magic as TableType in Syzygy trait.
• 0.2.2
  • Implement support for wide DTZ values. These are required for some long 7 piece endgames.
  • Fix panic on corrupted table.
• 0.2.1
  • Should not panic on corrupted tables (even in debug mode).
  • Switch from fnv to fxhash.
• 0.2.0
  • Replace Wdl::from(dtz) with Wdl::from_dtz_after_zeroing(dtz).
  • Remove isize conversions of Dtz and Wdl.
  • Fix WDL of lone king in atomic chess.
  • Support stable rust.
• 0.1.4
  • Fix ordering of lead pawns.
• 0.1.3
  • Add support for Atomic chess and Giveaway.
• 0.1.2
  • Cosmetic tweak to DTZ in case of mate in 1.
• 0.1.1
  • Optional serde-1 feature.
  • Add Dtz.add_plies().
• 0.1.0
  • First release.

Acknowledgement

Thanks to Ronald de Man for his Syzygy tablebases. The probing code is closely based on his implementation for Stockfish.

License

shakmaty-syzygy is licensed under the GPL-3.0 (or any later version at your option). See the COPYING file for the full license text.