Thrawn v3.2

v3.2 improves on v3.1 through a search rework (#21) and dynamic time management (#24): fail-soft search with retuned pruning/reduction heuristics/constants, plus time allocation that adapts to position complexity.

Combined gain over v3.1 is ~195 Elo (120+1, 1t, 256MB, UHO_Lichess_4852_v1.epd):

Search rework vs v3.1: +124.60 +/- 11.34 Elo, 1000 games
Time management vs above: +69.71 +/- 10.93 Elo, 1000 games

Thrawn v3.1

v3.1 achieved significantly greater performance than v3.0 from optimizations made in #16 and #18.
TLDR: low level code optimizations reducing nodes searched by 50% and performance improvements to a new nnue architecture.

v3.1 is estimated to be ~3476 Elo

NNUE is embedded to the executables

Thrawn v3.0

Thrawn v3.0 introduces a new native NNUE model, major search improvements, and broad engine performance work.
~3000 ELO

NNUE

• Integrated Thrawn’s new HalfKAv2_hm NNUE architecture
• Added incremental NNUE accumulator state directly to Position
• Added SIMD-aware NNUE paths for AVX2, AVX512, and NEON builds
• Added UCI EvalFile support for loading NNUE networks
• Fallback to handcrafted evaluation when NNUE is unavailable
• Replaced the old external-style NNUE interface with native Thrawn NNUE APIs
• Added NNUE refresh, copy, promotion, update, and verification helpers
• Updated make/unmake and null-move handling to preserve NNUE state

Engine Changes

• Refactored Position copy/init behavior and shared attack/hash table storage
• Improved move generation performance
• Reworked transposition table storage with clustered entries, aging, static eval storage, and prefetching
• Added and tuned search features including correction history, capture/quiet history, counter moves, LMR, ProbCut, futility pruning, and singular extensions
• Improved Lazy SMP/threaded search behavior and result selection

Notes

• NNUE file must be placed in the same directory of the executable or the engine will fallback to using HCE for evaluation

Thrawn v2.2

Thrawn v2.2
~3000 ELO (~200 ELO better than v2.1)

Changes:

• Introduced multithreaded search by Lazy SMP (see PR for more detail #9)
  • Default threads is 4
  • Change thread count using this uci command setoption name Threads value <number of threads>
• Search improvements (see PR for more detail #11)
  • Choose results from best thread
  • Improve stability of aspiration window
  • Refactor TT API and logic

Non-performance changes:

• Fix Search Score Returning 0 When uci Sends stop With No Time #6
• Redesign Core Logic: Implement Position Class for OO Architecture #7
• Add Perft Testing Functionality with Performance Metrics by #8
• Allocate position object copies on to the heap #12

IMPORTANT NOTE: nnue file must be placed in the same directory of the executable or the engine will play random moves

Compilation support for Windows, MacOS, and, Linux

Thrawn v2.1

Changes:

• Support for ARM chips
• Compilation support for Windows, MacOS, and, Linux

IMPORTANT NOTE: nnue file must be placed in the same directory of the executable or the engine will play random moves

Thrawn v2.0

Thrawn v2.0
~2800 ELO

IMPORTANT NOTE: nnue file must be placed in the same directory of the executable or the engine will play random moves

notice: this executable and source code below has been updated to fix some bugs. The current files are the most updated ones.

• fixed uci input parsing bug regarding tournament mode and switching sides
• fixed queen promotion bug where previously the engine promoted to other pieces when queen is clearly the best promotion type

new changes

• fixed zero evaluation blundering bug
• embedded NNUE (using pure NNUE evaluation)
• no-hashmove reduction
• reverse futility pruning / static null move pruning
• late move pruning

Thrawn v1.1

Thrawn is a UCI compliant chess engine that does not have its own GUI
Rated 2011 ELO in 2+1 blitz by CCRL

New updates:

• hash move ordering
• razoring

Features:

• bitboard representation
• PeSTO's evaluation + bonuses/penalties for piece mobility and safety
• negamax search
• alpha beta pruning
• principal variation search
• iterative deepening
• MMV-LVA move ordering
• move history
• late move reduction
• null move pruning
• zobrist hashing + transposition table (with dynamic memory allocated hashmap)
• time control

Thrawn v1.0

Thrawn is a UCI compliant chess engine that does not have its own GUI
~1900 ELO

Features:

• bitboard representation
• PeSTO's evaluation + bonuses/penalties for piece mobility and safety
• negamax search
• alpha beta pruning
• principal variation search
• iterative deepening
• MMV-LVA move ordering
• move history
• late move reduction
• null move pruning
• zobrist hashing + transposition table (with dynamic memory allocated hashmap)
• time control

ThrawnEngine v0.6-beta

v0.6
~1800 ELO

new changes

• improved search speed from fixing various bugs
• detecting 3-fold repetition
• zobrist hashing
• transposition tables

old updates

• added uci commands for timing control (search no longer fixed depth)
• null move pruning
• late move reduction
• iterative deepening (also adjusting aspiration window)
• principal variation search
• move history (quiet and killer)
• basic move ordering
• quiescence search
• negamax alpha beta search
• checkmate and stalemate
• basic static eval using piece square tables

ThrawnEngine v0.5-beta

~1800 ELO
added uci commands for timing control (search no longer fixed depth)