Steps 1 5 are for {HEAD ~ the generation} of {TAIL ~ a special set} [D} of n elements ds 
Steps 1 5 are for { HEAD ~ the generation } of { TAIL ~ a special set } [ D } of n elements ds
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH