{HEAD ~ A number} of {TAIL ~ unique combinations} of bids can be formed from the received bids, and the one combination of bids which represents the best value in terms of an auction setting, a reverse auction setting and an exchange setting can be determined 
of
{ HEAD ~ A number } of { TAIL ~ unique combinations } of bids can be formed from the received bids , and the one combination of bids which represents the best value in terms of an auction setting , a reverse auction setting and an exchange setting can be determined
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