August 6, 2008

Overview

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.