determining a lower bound price of a group of bids of {HEAD ~ a subtree} of {TAIL ~ the search tree} 
of
determining a lower bound price of a group of bids of { HEAD ~ a subtree } of { TAIL ~ the search tree }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL