Advanced chess is a form of chess in which each human player uses a computer chess program to explore the possible results of candidate moves. Despite this computer assistance, it is the human player who controls and decides the game. Also called cyborg chess or centaur chess, advanced chess was introduced for the first time by grandmaster Garry Kasparov, with the aim of bringing together human and computer skills to achieve the following results: increasing the level of play to heights never before seen in chess; producing blunder-free games with the qualities and the beauty of both perfect tactical play and highly meaningful strategic plans; offering the public an overview of the mental processes of strong human chess players and powerful chess computers, and the combination of their forces. A variant or superset of advanced chess is freestyle chess, in which teams are also allowed and, within the established time limits, every possible form of consultation. Freestyle chess was introduced by Ingo Althoefer and Timo Klaustermeyer with a Blitz tournament in August 2004. History The concept was already common in the 1970s: "An interesting possibility which arises from the 'brute force' capabilities of contemporary chess programs is the introduction of a new brand of 'consultation chess' where the partnership is between man and machine." The concept of computer-assisted chess tournaments originated in science fiction, notably in The Peace War written by Vernor Vinge in 1984. The former world champion grandmaster Garry Kasparov, who retired from competitive chess in 2005, has a long history in playing "Man vs. Machine" events. Among the most important are his matches against IBM's computer Deep Blue, which Kasparov defeated in February 1996, scoring 4–2 in a 6-game match, and lost to, –, in a May 1997 rematch. This 1997 match was famous, as it was the first time in the history of chess in which a world champion had been defeated by a computer. After this spectacular match, and many other matches against computers, Garry Kasparov had the idea to invent a new form of chess in which humans and computers co-operate, instead of contending with each other. Kasparov named this form of chess "advanced chess". The first advanced chess event was held in June 1998 in León, Spain. It was played between Garry Kasparov, who was using Fritz 5, and Veselin Topalov, who was using ChessBase 7.0. The analytical engines used, such as Fritz,