  Pro-drop is commonly seen in many languages, but its discourse motivations
have not been well characterized. Inspired by the topic chain theory in
Chinese, this study shows how character-verb usage continuity distinguishes
dropped pronouns from overt references to story characters. We model the choice
to drop vs. not drop as a function of character-verb continuity. The results
show that omitted subjects have higher character history-current verb
continuity salience than non-omitted subjects. This is consistent with the idea
that discourse coherence with a particular topic, such as a story character,
indeed facilitates the omission of pronouns in languages and contexts where
they are optional.
