such as the existence and properties of its antecedents. In fact, such information has been used for pronoun resolution in many heuristicbased systems. The S-List model (Strube, 1998), for example, assumes that a co-referring candidate is a hearer-old discourse entity and is preferred to other hearer-new candidates. In the algorithms based on the centering theory (Brennan et al., 1987; Grosz et al., 1995), if a candidate and its antecedent are the backwardlooking centers of two subsequent utterances respectively, the candidate would be the most preferred since the CONTINUE transition is always ranked higher than SHIFT or RETAIN. .
