A cooperative yes-no query system featuring discourse particles

Cooperat ive dialog systems wil l o f fer extended answers to questions, that is, they will vo lunteer information not exp l ic i t l y asked for . A complete response wil l be complex and the member sentences wil l evince an extensive paral le l , the ind i rect answer subst i tu t ing an a l ternat ive for a focus in the quest ion. Research on discourse part icles has shown that they are necessary to ensure coherence between adjacent sentences ev incing an extensive paral le l , tha t is, that they ref lect discourse relations as given in complex answers, so that such answers emerge as core contexts. Thus the proper mode of representat ion for discourse part icles in a system coincides with the f ramework of cooperat i ve quest ion-answer ing. The PASSAT system centers on the r61e of part icles in character iz ing and reflect ing relations such as under l ie complex response.