More specifically, this invention relates to {HEAD ~ a query transformation technique} to achieve {TAIL ~ more efficient query processing} of systems with varying query capabilities within a federated system 
to achieve
More specifically , this invention relates to { HEAD ~ a query transformation technique } to achieve { TAIL ~ more efficient query processing } of systems with varying query capabilities within a federated system
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH