AXWChessbot

This is a simple chess engine written in golang.

You can play against the engine here.

Strength

I have not been able to conduct a good comparison against other engines yet and furthermore I change the engine quite a bit, so the strength may vary from time to time. However the engine is available on lichess and there it beats stockfish on difficulty levels 1-4 (lichess rating levels of 800-1700) confidently on rapid 10+10 rules. Level 5 (rating 2000) is dominated by stockfish, but AXWChessBot manages to secure some wins as well.

So its strength should be between 1700 and 2000. Remember that this is a lichess rating which does not correspond to the FIDE elo ratings and that its strength also depends on the machine it is running on. More computing resources mean more depth in the search tree. The server running the bot on lichess provides enough resources for an average search depth of 5-6 plys.

WIP

This branch contains a full rewrite of the engine in golang. It is currently work-in-progress, but a lot of the original python functionality is already implemented.

Features

• Written in golang
• Basic UCI interface
• Simple timemanagement
• Simple evaluation function using
  • Gamephase detection of mid- and endgame
  • Piece value
  • Piece square tables
  • Tempo evaluation
  • Pair bonus
  • Rook on (half-)open files bonus
  • Passed pawn evaluation
  • Mobility evaluation
• Simple search algorithm using
  • Negamax with alpha-beta-pruning
  • Quiescence search
  • Iterative deepening
  • Simple Move ordering
  • Transposition tables as cache
  • Killer move heuristics

Features ideas

• Evaluation improvements
  • Pawnshield bonus
  • Blocked piece penalty
• Search improvements
  • Multiprocessing (Lazy SMP?)

Used materials / Research

• Chessprogramming-Wiki
• Stockfish source
• cpw-engine
• chess-ai
• sunfish
• Adam Berent Blog
• Dragontooth
• Dragontoothmg
• CounterGo
• Several blogposts/stackoverflow questions found via Google