corman

A chess engine written in Rust, built for fun in my free time.

How it works

The engine uses a bitboard-based board representation and searches with alpha-beta minimax. A few things it does:

• Move ordering via MVV-LVA to get better alpha-beta cutoffs
• Quiescence search to avoid the horizon effect on captures
• Null move pruning to speed up the search
• Transposition table with Zobrist hashing to avoid re-evaluating the same position
• Parallel search at the root using rayon
• Static evaluation based on material, piece-square tables, and attacked squares

It uses UCI protocol, so you can plug it into any UCI-compatible GUI or lichess-bot.

Building

cargo build --release

Benchmarks

bench.sh runs the benchmarks, compares against the previous baseline, and saves the results to benches/results.md. It's used to keep a minimal record of performance across commits.

./bench.sh

For more detailed analysis, HTML reports with graphs are written to target/criterion/ after any bench run.

Testing against Stockfish

Requires cutechess-cli and Stockfish installed.

Build the engine first:

cargo build --release

Then run:

cutechess-cli \
  -engine name=corman cmd=./target/release/corman \
  -engine name=stockfish cmd=stockfish option.UCI_LimitStrength=true option.UCI_Elo=1800 \
  -each proto=uci tc=40/10 \
  -openings format=epd file=2moves_v1.epd order=random \
  -games 10 -repeat -concurrency 1 \
  -pgnout results.pgn

• tc=40/10 -> 40 moves in 10 seconds per side
• UCI_Elo=1800 -> limits Stockfish strength (raise to make it harder)
• -games 10 -repeat -> plays each opening twice (once per color)
• -pgnout results.pgn -> saves the games for review

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Btw: Cornelia 🐈 + Norman 🐈‍⬛ = Corman. They're my cats.