The processing unit receives a query for an item and uses {HEAD ~ the features index} to determine {TAIL ~ search results} including the item, such as a location and a time of the item 
to determine
The processing unit receives a query for an item and uses { HEAD ~ the features index } to determine { TAIL ~ search results } including the item , such as a location and a time of the item
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH