...is a computer chess engine that is capable of the WinBoard protocol and the UCI protocol. That means you can use it for example with Fritz or Shredder by installing it as an UCI engine (there's a menu option for it). The current version 4.50 scores about equal with Ruffian 1.0.1. Download here.
Aristarch works perfectly with ChessBase Fritz, ChessBase Shredder and the freeware GUI WinBoard (see section GUIs).
Aristarch's positional knowledge specializes in long-term attacks and the engine is willing to make big concessions only to weaken the opponent's king position. Sometimes Aristarch makes hazardous speculations, but in most cases its estimation is correct. An example:
White to move. Aristarch plays f5-f6! after about 5 seconds.
The first version of Aristarch I wrote in 1995. Version 2.x has played lots of games in the ICC, won against most IMs, but scored extremely bad against other computers. Version 3.0 is a complete rewrite and is the first version that uses bitboards. Version 4.0 includes several improvements, the most important being a completely new pawn evaluation routine.
The name of the engine has its origin in a not very well-known Greek astronomer who lived more than 2000 years ago and managed to discover things that are normally credited to Copernicus and Galilei. More here.
If you want to use WinBoard (see section GUIs), there are two command line options:
||set hash table size to <n> MB|
||set path to Nalimov end game table bases|
||activate book learning|
Many thanks to an endless list of people who tested Aristarch and made suggestions for improvement!