Technologies in 2001: A Space Odyssey well, such as a nervous breakdown—as Hal did in the film. Clarke noted that, contrary to popular rumor, it was a complete coincidence that each of the letters of Hal's name immediately preceded those of IBM in the alphabet. The meaning of HAL has been given both as "Heuristically programmed ALgorithmic computer" and as "Heuristic ALgorithmic computer". The former appears in Clarke's novel of "2001" and the latter in his sequel novel "2010". In computer science, a heuristic is a programmable procedure not necessarily based on fixed rules, producing informed guesses often using trial-and-error. The results can be false such
2001: A Space Odyssey (novel) HAL denies him reentry and kills the hibernating crew members by turning off their life-support. In the sequel "2010: Odyssey Two," however, the recounting of the "Discovery One" mission is changed to the film version. The film is generally far more enigmatic about the reason for HAL's failure, while the novel spells out that HAL is caught up in an internal conflict because he is ordered to lie about the purpose of the mission. Because of what photographed well, the appearance of the monolith that guided Moon-watcher and the other 'man-apes' at the beginning of the story was changed from