History
The history of DCGs is closely tied to the history of Prolog, and the history of Prolog revolves around several researchers in both Marseilles, France, and Edinburgh, Scotland. According to Robert Kowalski, an early developer of Prolog, the first Prolog system was developed in 1972 by Alain Colmerauer and Phillipe Roussel. The first program written in the language was a large natural-language processing system. Fernando Pereira and David Warren at the University of Edinburgh were also involved in the early development of Prolog.
Colmerauer had previously worked on a language processing system called Q-systems that was used to translate between English and French. In 1978, Colmerauer wrote a paper about a way of representing grammars called metamorphosis grammars which were part of the early version of Prolog called Marseille Prolog. In this paper, he gave a formal description of metamorphosis grammars and some examples of programs that use them.
Fernando Pereira and David Warren, two other early architects of Prolog, coined the term "definite clause grammar" and created the notation for DCGs that is used in Prolog today. They gave credit for the idea to Colmeraur and Kowalski, and they note that DCGs are a special case of Colmeraur's metamorphosis grammars. They introduced the idea in an article called "Definite Clause Grammars for Language Analysis", where they describe DCGs as a "formalism ... in which grammars are expressed clauses of first-order predicate logic" that "constitute effective programs of the programming language Prolog".
Pereira, Warren, and other pioneers of Prolog later wrote about several other aspects of DCGs. Pereira and Warren wrote an article called "Parsing as Deduction", describing things such as how the Earley Deduction proof procedure is used for parsing. Pereira also collaborated with Stuart Sheiber on a book called "Prolog and Natural Language Analysis", that was intended as a general introduction to computational linguistics using logic programming.
Read more about this topic: Definite Clause Grammar
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