Overlooked No More: Karen Sparck Jones, Who Established the Basis for Search Engines

"All words in a natural language are ambiguous; they have multiple senses," she said in an oral history interview for the History Center of the Institute of Electrical and Electronics Engineers. "How do you find out which sense they've got in any particular use?" In 1964, Sparck Jones published "Synonymy and Semantic Classification," which is now seen as a foundational paper in the field of natural language processing. In 1972, she introduced the concept of inverse document frequency, which counts the number of times a term is used in a document in order to determine the term's importance; it, too, is a foundation of modern search engines. Sparck Jones began working on early speech recognition systems in the 1980s.