Centering: A Framework for Modeling the Local Coherence of Discourse

8 Requisite properties of underlying semantic theory

1. Why must a semantic theory for centering support partial interpretations?
   The information needed for a unique interpretation (especially of definite noun phrases) may only arrive in later utterances; computing all interpretations or backtracking are costly, so the authors conjecture partial interpretations refined later are the right choice.
   • Grosz et al., 1995, Centering (Computational Linguistics), §8
2. What do the “Vice-President” examples show about the forward-looking centers?
   A definite NP can contribute both a value-free interpretation (the role: “Historically, he is the President’s key man…”, “He is required to be 35 years old”) and a value-loaded one (the current holder: “As Ambassador to China, he…”); a later pronoun can pick up either, unless an earlier utterance forced one.
   • Grosz et al., 1995, Centering (Computational Linguistics), §8
3. What does the “Her husband is kind to her” example show?
   Speaker’s referential intentions matter: one NP can contribute two entities (the actual husband and the man the speaker meant) to \(C_f\), and the next utterance’s \(C_b\) can be either.
   • Grosz et al., 1995, Centering (Computational Linguistics), §8