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Dendral was an influential pioneer project in artificial intelligence (AI) of the 1960s, and the computer software expert system that it produced. Its primary aim was to study hypothesis formation and discovery in science. For that, a specific task in science was chosen: help organic chemists in identifying unknown organic molecules, by analyzing their mass spectra and using knowledge of chemistry.〔November, 2006〕 It was done at Stanford University by Edward Feigenbaum, Bruce G. Buchanan,〔(Oral history interview with Bruce G. Buchanan ), Charles Babbage Institute, University of Minnesota.〕 Joshua Lederberg, and Carl Djerassi, along with a team of highly creative research associates and students.〔Lederberg, 1987〕 It began in 1965 and spans approximately half the history of AI research.〔Lindsay et al., 1980〕 The software program Dendral is considered the first expert system because it automated the decision-making process and problem-solving behavior of organic chemists.〔 The project consisted of research on two main programs Heuristic Dendral and Meta-Dendral,〔 and several sub-programs. It was written in Lisp (programming language), which was considered the language of AI because of its flexibility.〔 Many systems were derived from Dendral, including MYCIN, MOLGEN, PROSPECTOR, XCON, and STEAMER. There are many other programs today for solving the mass spectrometry inverse problem, see List of mass spectrometry software, but they are no longer described as 'artificial intelligence', just as structure searchers. The name ''Dendral'' is a portmanteau of the term "Dendritic Algorithm".〔 ==Heuristic Dendral== Heuristic Dendral is a program that uses mass spectra or other experimental data together with knowledge base of chemistry, to produce a set of possible chemical structures that may be responsible for producing the data.〔 A mass spectrum of a compound is produced by a mass spectrometer, and is used to determine its molecular weight, the sum of the masses of its atomic constituents. For example, the compound water (H2O), has a molecular weight of 18 since hydrogen has a mass of 1.01 and oxygen 16.00, and its mass spectrum has a peak at 18 units. Heuristic Dendral would use this input mass and the knowledge of atomic mass numbers and valence rules, to determine the possible combinations of atomic constituents whose mass would add up to 18.〔 As the weight increases and the molecules become more complex, the number of possible compounds increases drastically. Thus, a program that is able to reduce this number of candidate solutions through the process of hypothesis formation is essential. New graph-theoretic algorithms were invented by Lederberg, Harold Brown, and others that generate all graphs with a specified set of nodes and connection-types (chemical atoms and bonds) -- with or without cycles. Moreover, the team was able to prove mathematically that the generator is complete, in that it produces all graphs with the specified nodes and edges, and that it is non-redundant, in that the output contains no equivalent graphs (e.g., mirror images). The CONGEN program, as it became known, was developed largely by computational chemists Ray Carhart, Jim Nourse, and Dennis Smith. It was useful to chemists as a stand-alone program to generate chemical graphs showing a complete list of structures that satisfy the constraints specified by a user. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dendral」の詳細全文を読む スポンサード リンク
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