Abduction

Definition

Abduction is the task of finding an explanation for an observation with respect to the given knowledge.

Characteristics

The key principle underlying abduction is that of hypothesizing a set of facts that, together with the available knowledge, explain a specific observation. For instance, given background knowledge about flying and non-flying objects, including a rule stating that normal birds fly ($\forall x.bird(x) \wedge normal(x) \to flies(x)$), the observation that Tweety flies (flies(tweety)) can be explained by abducing that Tweety is a normal bird ({bird(tweety), normal(tweety)}).

More formally, given background knowledge B, a set A of abducibles (i.e., facts that can be part of explanations), and a ground fact or observation o, the task of abduction is to find an explanation for o, that is, a set of facts E⊆A such that o can be inferred from B∪E using deduction.

Similarly to induction, abduction can be seen as a form of inverted deduction. However, whereas...