Changes

SOS is an amateur program which was started in 1993 and has since then competed in a number of [[Tournamentsand Matches|tournaments]]. The newest version runs on multiprocessor systems with a parallelized version of [[MTD(f)|mtd(f)]] as its minimax search algorithm. SOS used to be a relatively fast searcher and relied on outsearching the opponent. This has changed now and more [[Knowledge|knowledge]] and special cases have been implemented which slow it down. Little effort is spent on the opening book. It plays a very broad range of openings. However it [[Book Learning|learns]] to avoid unsuccessful lines and tries not to repeat lost games. It uses publicly available [[Endgame Tablebases|endgame databases]].