As we will discuss in section 3 about features, we are working on very high dimensional feature space, and this often leads to overfitting.
for example, relations such as "a town west of Jerusalem", "park outside Paris", "his friend/wife/brother" are highly dependent on the lexical feature, i.e., "west of", "outside", and "friend/wife/brother" are the most important clue to determine the class of the relations.