A government agency is accepting tenders for the construction of a public building. There are n firms with an interest in undertaking the project. Each firm i has a minimum cost C; that it would incur in construction. (C includes the opportunity cost of capital.) The contract will be awarded by having the firms submit sealed bids. Firm r's bid B, is the amount of money that it requires to undertake the project. The contract will be awarded to the firm submitting the lowest bid and that firm will be paid an amount of money equal to the second-lowest bid.

Prove that a bid of Ci, is a dominant strategy for arbitrary firm i