Complex sentence: It was declared the Man-Machine World Champion in checkers in 1994 against Marion Tinsley after six drawn games and Tinsley's withdrawal for health reasons; it then defended its title against Don Lafferty when it lost one game, won one and drew 18.
Split into simpler sentences: It was declared the Man-Machine World Champion in checkers in 1994 against Marion Tinsley after six drawn games and Tinsley's withdrawal for health reasons. Chinook then defended its title against Don Lafferty when it lost one game, won one and drew 18.