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Home * Engines * Ruffian

a chess engine developed by Perola Valfridsson since 1998, which appeared in July 2002 as a surprisingly strong newcomer playing on ICC and FICS [1], supporting both, the Chess Engine Communication Protocol and UCI.


With portability and performance in mind, Ruffian was written in C, and used a hybrid board representation of bitboard and 8x8 board. It performs PVS with null move pruning and other forward pruning techniques as well as a few own algorithms and tricks [2]. One of the major evaluation terms is mobility based on pre-calculated tables considering various patterns [3] [4].



ICT 2004 winners: Chrilly Donninger, Erdogan Günes (Hydra 2nd), Stefan Meyer-Kahlen (Shredder 1st),
Johan Havegheer (Ruffian 3rd), Vincent Diepeveen (Diep 3rd) [5]


Ruffian was shared winner of the CCT5 and lonesome winner of the DOCCC 2003 supported by book author Đorđe Vidanović, operated by Johan Havegheer, Frank Quisinsky and Leo Dijksman [6] [7], winner of the (unofficial) Swedish Championship in 2003 [8], and further played a strong CCT6 and ICT 2004.

Free Ruffian

The free Windows versions 1.0 from September 2002 is still available for download from Ed Schröder's Winboard and UCI engines download site [9].

Commercial Ruffian

In 2003, Ruffian 2 went commercial, first bundled with Chess Assistant by Convekta, where Victor Zakharov mentions Dann Corbit was a big help [10], and further with the otherwise free Arena GUI, CD production by Frank Quisinsky and distribution by Schachversand Niggemann [11], and soon as bundle with ChessPartner by Lokasoft [12]. Ruffian is base of the chess AI in Kasparov Chessmate [13], with Perola Valfridsson credited as author by MobyGames [14]. The initial hype about Ruffian's commercialization was apparently detrimental to its authors motivation to continue the development [15]. In conjunction with the upcoming strong free engines catching up, this was slowly but surely the fall of the commercial endeavor [16]. In May 2017, Frank Quisinsky rescued Ruffian versions 2.02 and 2.1 from their commercial burdens [17].

See also

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