••• Current position: Release notes
Rybka engine
Computer chess
Rybka team

Rybka 3
August 6, 2008


Rybka 3 is the latest UCI chess engine from the Rybka line. Our previous version, Rybka 2.3.2a, is now nearly 14 months old, so the changes are extensive.

Major Changes

- The evaluation function is more accurate. There is a long list of useful new evaluation terms. The terms also interact in a more balanced and mature way.
- The search is more efficient, especially in the sorts of sharp, murky positions in which chess games are often decided.
- The multi-processor support is improved.
- The code and algorithms have been cleaned up, leading to more solid and predictable behavior.
- The opening book is improved and expanded and now fills the role of a general reference. Note: this book is sold separately, details here.

New Features

- Persistent hash, for storing and loading previous analysis
- More efficient multi-variation mode
- Chess 960 support
- More intelligent contempt, which takes into account the trading of material, symmetrical structures and other drawish features
- A special "human" version, whose evaluation aims at consistency with human grandmaster practice rather than at success in computer vs computer play
- A special "dynamic" version, whose evaluation aims at speculative play

There are also a number of other new features which enhance the analytical process but which require interface support. These can be used in the ChessBase and Convekta interfaces which are sold with Rybka 3. Details can be found in the documentation for those interfaces.

User Area

All information relevant to Rybka 3 usage is collected here. This includes parameter descriptions, FAQ, installation instructions, known engine issues, etc.


A huge thanks to everyone on the Rybka team, without whom this project would be much less successful and a lot less fun:

- Larry Kaufman for his incredibly accurate work with Rybka's static evaluator (and for not letting me forget about Monte Carlo)
- Jeroen Noomen for again finding a way to push the boundaries in opening book quality and for his never-satisfied approach
- Iweta for Rybka testing, ideas and moral support :)
- Felix Kling and Christoph Kling for an excellent and innovative web site
- Lukas Cimiotti for always having an 8-core machine or three ready for testing, tournament play or analysis (by patzers and non-patzers alike)
- Hans van der Zijden for traveling around the world (or at least North-Western Europe) as our tournament operator
- Nick Carlin for ICC play, opening preparation and testing help
- Dagh Nielsen for contributing to Jeroen's opening book while entertaining the rest of us with his unique working style
- Victor Zakharov and his team from Convekta and Mathias Feist from ChessBase for their enthusiastic interface work
- Rybka testers for not letting the obvious perfection of the code discourage them
- Rybka forum regulars for a steady stream of often-interesting and occasionally-practical ideas

What's Next?

We will consider a number of Rybka ports to other platforms in the next few months. Aside from that, we'll go back into our cave and in the summer of 2009 we'll emerge with Rybka 4.