Development of the World Chess Championship five incredibly close world championship matches, the World Chess Championship 1984 (controversially terminated without result with Karpov leading +5 -3 =40), World Chess Championship 1985 (in which Kasparov won the title, 13–11), World Chess Championship 1986 (narrowly won by Kasparov, 12½–11½), World Chess Championship 1987 (drawn 12–12, Kasparov retaining the title), and World Chess Championship 1990 (again narrowly won by Kasparov, 12½–11½). In 1993, Kasparov and challenger Nigel Short complained of corruption and a lack of professionalism within FIDE and split from FIDE to set up the Professional Chess Association (PCA), under whose auspices they held their match. FIDE and
Development of the World Chess Championship dropped the short knockout format for World Championship and announced the FIDE World Chess Championship 2005, a double round robin tournament to be held in San Luis, Argentina between eight of the leading players in the world. However, Kramnik insisted that his title be decided in a match, and declined to participate. The tournament was convincingly won by the Bulgarian Veselin Topalov, and negotiations began for a Kramnik-Topalov match to unify the title. The FIDE World Chess Championship 2006 reunification match between Topalov and Kramnik was held in late 2006. After much controversy, it was won by Kramnik. Kramnik thus