56. The method of claim 46 , wherein the query has one or more query blocks and wherein determining the set of candidate queries for each starting query comprises determining a particular semantically equivalent query based on the starting query and an alternative query block, wherein the alternative query block is determined based on a first query block of the one or more query blocks.
56. The method of claim 46 , wherein the query has one or more query blocks and wherein determining the set of candidate queries for each starting query comprises determining a particular semantically equivalent query based on the starting query and an alternative query block, wherein the alternative query block is determined based on a first query block of the one or more query blocks. 57. The method of claim 56 , wherein the method further comprises the step of determining the alternative query block based on the first query block.