  In machine translation and man-machine dialogue, it is important to clarify
referents of noun phrases. We present a method for determining the referents of
noun phrases in Japanese sentences by using the referential properties,
modifiers, and possessors of noun phrases. Since the Japanese language has no
articles, it is difficult to decide whether a noun phrase has an antecedent or
not. We had previously estimated the referential properties of noun phrases
that correspond to articles by using clue words in the sentences. By using
these referential properties, our system determined the referents of noun
phrases in Japanese sentences. Furthermore we used the modifiers and possessors
of noun phrases in determining the referents of noun phrases. As a result, on
training sentences we obtained a precision rate of 82% and a recall rate of 85%
in the determination of the referents of noun phrases that have antecedents. On
test sentences, we obtained a precision rate of 79% and a recall rate of 77%.
