These properties are often used to aid coreference resolution:

• Number Agreement
• Person Agreement
• Gender/Noun Class Agreement
• Binding Theory -> mentions within the same sentence typically require a reflexive pronoun such as himself to corefer
• Recency -> mentions are more likely to corefer with more recent utterances that older ones
• Grammatical role -> Entities mentioned in subject position are more salient than those in object position, which are in turn more salient than those mentioned in oblique positions
• Verb semantics -> semantic meaning of verbs can help bias the interpretation of subsequent pronouns