Anaphoric Relations

Generally speaking, many different kinds of relationships can be established between an anaphor and its antecedent. Examples are co-reference (``John saw Mary. He$\ldots$''), part-whole (``John bought a car. The engine$\ldots$''), and individual-class (``John bought a truck. They are good for hauling$\ldots$'') (see, for example, [40]). The latter two involve bridging descriptions (see, for example, [7,12,29]): some reasoning is required to infer the correct interpretation. This section presents a set of anaphoric relations that have good coverage for temporal expressions in scheduling dialogs (see Section 8.2 for an evaluation). Many temporal references involve bridging inferences, in the sense that times are calculated by using the antecedent as a frame of reference or by modifying a previous temporal interpretation.