Given the potential usefulness of lexical relations for temporal relation classification, we create features based on four types of lexical relations present in Webster's online thesaurus 5 , namely synonyms, related-words, near-antonyms, and antonyms.
for each event e appearing in TimeBank, we first use the head word of e to retrieve four lists, which are the lists corresponding to the synonyms, related words, near-antonyms, and antonyms of e. Then, given a training/test instance involving e 1 and e 2 , we create eight binary features: whether e 1 appears in e 2 's list of synonyms/related words/near-antonyms/antonyms, and whether e 2 appears in e 1 's list of synonyms/related words/nearantonyms/antonyms.