Several approaches for this step have been proposed such as the longest common substring (Agichtein et al., 2001), substrings in suffix trees (Ravichandran and Hovy, 2002;Ruiz-Casado et al., 2007) and edit distance based alignment (Ruiz-Casado et al., 2007).
a portion of the retrieved sentences can be, to a certain degree, not relevant in describing the intended relation.