determining {HEAD ~ a difference} between a sum of the prices of the bid that lie on a search path connected to said subtree and {TAIL ~ the current price} of the best allocation 
between
determining { HEAD ~ a difference } between a sum of the prices of the bid that lie on a search path connected to said subtree and { TAIL ~ the current price } of the best allocation
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH