For that purpose, most past work (Appelt, 1985;Dale and Haddock, 1991;Dale, 1992; Dale and Reiter, 1995;Heeman and Hirst, 1995;Horacek, 1997;Krahmer and Theune, 2002;van Deemter, 2002;Krahmer et al., 2003) makes use of attributes of an intended object (the target) and binary relations between the target and others (distractors) to distinguish the target from distractors.
these methods cannot generate proper referring expressions in situations where no significant surface difference exists between the target and distractors, and no binary relation is useful to distinguish the target.