If {TAIL ~ an inexact transformation} improves the query performance, the system prioritizes {HEAD ~ the candidate transformation rules} applicable to the selected query element 
If { TAIL ~ an inexact transformation } improves the query performance , the system prioritizes { HEAD ~ the candidate transformation rules } applicable to the selected query element
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH