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