5. The method of claim 2 , further comprising: generating the set of covering tokens to include at least some tokens that are included in a plurality of the entity strings to reduce a total number of tokens included in the set of covering tokens.
5. The method of claim 2 , further comprising: generating the set of covering tokens to include at least some tokens that are included in a plurality of the entity strings to reduce a total number of tokens included in the set of covering tokens. 6. The method of claim 5 , where said generating comprises: generating the set of covering tokens according to a greedy heuristic.