deficit theory code theory definiendum definition definiens definition definite clause definite clause grammar definite clause grammar (abbrev. DCG)

Term used in formal logic that goes back to Frege (1892) and Russell (1905) and denotes expressions that describe certain objects with the aid of the definite article the and a predicate that applies to exactly one entity. For example, the property designated by the propositional form father (x, W.A.Mozart) applies exactly to only one person, namely to Leopold Mozart, who is designated by the definite description of the father of W.A.Mozart. Such definite descriptions, which are used to identify particular entities, are introduced in formal logic by means of the so-called iota operator ( operator2c).