5. The method of claim 3 , wherein calculating the cost comprises: associating, by the mobile client system, one of the accessed nodes to one of the non-terminal tokens; and incurring the insertion cost for the non-terminal token and the associated accessed node based on the associated accessed node not corresponding to one of the n-grams.
3. The method of claim 2 , wherein: each non-terminal and query token having an associated insertion cost; and calculating the cost comprises incurring an insertion cost for each of the non-terminal or query tokens not corresponding to one or more n-grams.