Computational Linguistics

Abstract

Computational linguistics (CL) is an interdisciplinary mix of computer science and linguistics with additional insights drawn from areas such as psycholinguistics and the philosophy of language. Its primary concern is with the computational modeling of linguistic processes pursued as a theoretically oriented exercise whose purpose is either to provide models that help us gain insight into the nature of language and the human language processing mechanism or to support the development of software applications that do useful things with language (an area sometimes referred to as language technology). For some, the term “computational linguistics” is synonymous with natural language processing (NLP); however, from the perspective of the material provided here, NLP is more applications-oriented than CL. Although we provide some pointers to work that describes NLP applications, our primary focus here is on the theoretical underpinnings that CL provides to activities with a more practical focus. The first work in CL dates from the 1950s, when initial attempts were made to automatically translate Russian into English. Until the late 1980s most work in the field was concerned with what we might call symbolic systems, often involving large collections of handwritten rules to model some linguistic phenomenon. Since the late 1980s there has been a significant shift toward statistical methods, where rules and generalizations are learned from data rather than being produced manually; this has become possible only as a result of the combination of, on one hand, vast amounts of data becoming available, particularly via the World Wide Web, and, on the other hand, the immense increases in computer processing power required to execute many iterations over large data sets to derive information from them. In almost all subareas of CL one can generally divide the work pursued into the periods before and after this “statistical revolution.” The material here is organized around the conventional decomposition of linguistic study into phonology, morphology, syntax, semantics, and pragmatics. Work that is primarily concerned with speech recognition and synthesis is not covered. Primarily concern is with work on the processing of English; again, much of the work in CL is applicable to other languages, but English holds a privileged position as the focus of most research.