For example, the analyzed behaviors may include the item purchases, {HEAD ~ item rentals}, item viewing activities, web browsing activities, and search histories of {TAIL ~ the users} 
For example , the analyzed behaviors may include the item purchases , { HEAD ~ item rentals } , item viewing activities , web browsing activities , and search histories of { TAIL ~ the users }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL