While we could easily understand the dropped pronoun refers to "我(I)" from the previous sentence, it is difficult to make this determination by just looking at the second sentence independently.
we propose a list of novel context-based features tailored towards SMS/Chat data to capture such information: • previous pronoun used by the same participant; • previous pronoun used by the other participant; • all previous pronouns till the beginning of a sentence or a punctuation mark used; • next punctuation mark; • if it is a question; • if the POS tag of the last word is SP; • for the first word in a sentence, use first two nouns/pronouns from the previous sentence.