On {HEAD ~ basis} of {TAIL ~ the distribution graph}, the shortest paths from the distribution node to each of the other nodes are calculated 
of
On { HEAD ~ basis } of { TAIL ~ the distribution graph } , the shortest paths from the distribution node to each of the other nodes are calculated
OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH