repetitions which refer to an identical object; or there is a strong sentence similarity between the current question and the previously asked questions.
: 1. q 0 has pronoun and possessive adjective references to q -1 ..q -n 2. q 0 does not contain any verbs 3. q 0 has repetition of common or proper nouns in q -1 ..q -n or q 0 has a strong semantic similarity to some q ∈ q -1 ..q -n A major part of our clarification dialogue recognition algorithm is the sentence similarity metric which looks at the similarity in meaning between the current question and previous questions.