An inference process widely used in artificial intelligence, particularly in expert systems and production rule system. In diagnosis, for example, there may be a rule like ‘if measles then red spots’ so that, when the symptom red spots occurs, we may use the rule in reverse to conclude that measles is present. However, unlike deduction, abduction is not logically sound because of inherent uncertainty that can lead to false conclusions—note that measles is not the only cause of red spots. Abduction is an example of a plausible reasoning technique.