4. The method of claim 1 , wherein identifying the plurality of second sequences of terms comprises: generating an expansion/contraction table that includes pairs of sequences of terms having highest respective similarity measures; and identifying a plurality of pairs of sequences of terms that include the first sequence of terms in the expansion/contraction table.
4. The method of claim 1 , wherein identifying the plurality of second sequences of terms comprises: generating an expansion/contraction table that includes pairs of sequences of terms having highest respective similarity measures; and identifying a plurality of pairs of sequences of terms that include the first sequence of terms in the expansion/contraction table. 5. The method of claim 4 , wherein generating the expansion/contraction table comprises: determining a plurality of frequently occurring word sequences; and filtering out non-phrasal word sequences from the frequently occurring word sequences, wherein a non-phrasal word sequence is a word sequence that does not occur at a beginning or an end of at least a threshold number of queries in a collection of queries.