There are now a number of sellers from set M, and buyers from set N. Each seller j can deliver one unit of the good at some price cj ≥ 0whichisonly known to him, and each buyer i desires to buy at most one unit of the good, which she values at vi, only known to her.
1. Suppose there is only 1 seller. He runs an auction in which the winning bidder (the highest bidder) pays the price equal to the second-highest bid. If the seller wanted to make sure to not make a loss, what would he want to add to the rules of the auction?