Seer

Seer is an original, strong UCI chess engine. Seer relies on a neural network estimating WDL probabilities for position evaluation. Seer's network is trained through a novel retrograde learning approach starting only from 6-man syzygy EGTB WDL values. These initial WDL scores are then iteratively backed up to 32-man chess positions using Seer's search to find continuations from N-man chess positions to N-1-man chess positions (implementation). Seer uses a conventional alpha-beta search combined with "Lazy SMP" (shared transposition table) for multithreading support.

UCI Options

• OwnBook (specifies whether or not to use a separate opening book)
• BookPath (path to a file containing book positions in a supported format)
• Threads (for every thread doubling, a gain of about 70-80 elo can be expected)
• Hash (the amount of the memory allocated for the transposition table (actual memory usage will be greater))
• Weights (the absolute path to a binary weights file. If the default "EMBEDDED" path is chosen, the embedded weights will be used.)

Features

• From scratch neural network training and execution (using OpenMP SIMD directives and SIMD intrinsics) implementation (training scripts use PyTorch for GPU acceleration and can be found here).
• Plain magic bitboard move generation with constexpr compile time generated attack tables.
• Principal variation search inside an iterative deepening framework
• Lockless shared transposition table (using Zobrist hashing)
• Move Ordering (SEE for captures + Killer Move, Combined Butterfly History, Counter Move History and Follow Up History for quiets)
• History pruning as well as SEE pruning in QSearch
• History extensions
• Null move pruning
• Static null move pruning (reverse futility pruning)
• Futility pruning
• Late move reductions
• Aspiration windows

Compiling

The latest network can be found here

cd build
wget -O eval.bin https://github.com/connormcmonigle/seer-training/releases/download/0xbe759eb2/0xbe759eb2.bin
make pgo EVALFILE=eval.bin