The design and implementation of a paraphrase component for a natural language questlon-answer system (CO-OP) is presented. A major point made is the role of given and n e w information in formulating a paraphrase that differs in a meaningful way from the user's question. A description is also given of the transformational grammar used by the paraphraser to generate questions. I• INTRO~ION fact, a lexicon and database schema are the only items which contain domain-specific information. Consequently, the CO-OP system is a portable one; a change of database requires that only these two knowledge sources be modified. .
