An application program from {HEAD ~ a plurality} of {TAIL ~ application programs} is executed on an operating system of a personal computer 
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An application program from { HEAD ~ a plurality } of { TAIL ~ application programs } is executed on an operating system of a personal computer
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH