The process 52 wherein each of {TAIL ~ the parallel processing elements} generates an intermediate result for {HEAD ~ its respective partition} 
The process 52 wherein each of { TAIL ~ the parallel processing elements } generates an intermediate result for { HEAD ~ its respective partition }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD