In addition, Table 1, again extracted from (Bentivogli et al., 2009), suggests that the de-gree of word overlap among positive and negative pairs might be a key to understand the complexity of a text-to-text inference task, and, as a consequence, a key to interpret the system's performance.
we can notice that the word overlap for the "Yes" cases and the "Contradiction" cases in the RTE-4 data-set is very similar, and even higher for the RTE-5 data-set.