Arcadia 0.0.9

Hello there! Have fun with my chess engine "Arcadia"!

Why is it called Arcadia? It's a port to C++ of my Java engine "Eden", which is a tribute to a program called PARADISE. For simplicity's sake I just googled for a synonym of "Eden".

How to use it

Use a program like "Arena" (www.playwitharena.com) to play against it, or let other engines play against it, even have tournaments, or let it solve problem test suites (usually contained in ".epd" files.

This is version 0.0.9, released 2015-06-06. You can freely use it.

Features

• supports the very basics of the UCI protocol (for chess engines)
• knows all rules of chess, including castling and en passant
• can sub-promote if necessary, i. e. take a knight instead of a queen on promotion
• knows about stalemate

Some implementation notes

• straightforward alpha-beta
• Iterative Deepening
• naive Quiescence Search using only captures
• Basic Shannon-type (one-dimensional array) 10 x 9 board
• Pseudolegal move generation
• Copy/Make rather than make/unmake

Playing strength

• It is very weak, maybe around 1100 Elo on the usual chess engines Elo lists
• Version 0.0.9 is quite a bit stronger than version 0.0.8 in a test tournament I ran (2/6 time), and quite a bit better in wac.epd.
• significantly stronger than Eden 0.0.8, roughly the same strength as Eden 0.0.9

Test suites I ran

WAC 300 (Intel i7 3930k, 20 seconds per move)

• 0.0.5: 92
• 0.0.6: 97
• 0.0.7: 123
• 0.0.8: 102
• 0.0.9: 135 (130 @ 10 seconds, 153 @ 1 min, 164 @ 2 min)

UCI protocol features

• go, defaults to "infinite", but will use wtime, winc, btime, binc, movestogo
• stop
• only "id", "uciok", "readyok" and "bestmove" (without "ponder") is sent back

Perft

• embarrassingly slow "perft" command (e. g. "perft 7")
• "divide" command

TODO LIST = Limitations/Known Bugs/Future Features (in no particular order)

• Speeding up pawn structure evaluation (by dynamic programming / a pawn structure hashtable)
• Get all the features of Eden 0.0.13 in.

Probable focus for the next version

• more raw speed
• whatever else it takes to beat this version!

If you test this, please let me know your results. I love feedback (criticism, questions, tournament reports, games played by Eden, ...)! myfirstname.mylastname@gmail.com, replace myfirstname and mylastname by, well, ...)

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• GitHub: https://github.com/nczempin
• BitBucket: https://bitbucket.org/nczempin

Changes from 0.0.8->0.0.9

• basic endgame detection and evaluation

Changes from 0.0.7->0.0.8

• Re-enabled quiescence search

Changes from 0.0.6->0.0.7

• Fixed mate and stalemate detection bug
• Introduced some significant new bugs, probably with quiescence search

Changes from 0.0.5->0.0.6

• switched from fully legal to pseudo-legal
• various "comfort" features such as displaying nodes and nps properly
• migrated more parts of Eden's evaluation function
• gave the move generator vector an initial size
• more optimizations and bugfixes

Changes from 0.0.4->0.0.5

• optimizations and bugfixes
• accepts commands asynchronously (yay, C++11!)

Nicolai Czempin

P. S. This chess engine is dedicated to Pavel and Janik.