Some factors such as morphology (gender, number, animacy, and case) or syntax (e.g., the role of binding and commanding relations [Chomsky 1981]) are "eliminating," forbidding certain NPs from being antecedents.
many others are "preferential," giving more preference to certain candidates over others; examples include: r Sentence-based factors: Pronouns in one clause prefer to refer to the NP that is the subject of the previous clause (Crawley, Stevenson, and Kleinman 1990).