Bidding box for home-played games. Use of bidding boxes has several advantages over oral bidding: it reduces noise in the room, prevents bidding being overheard at neighboring tables, allows easier review of the auction, and reduces the opportunity to pass unauthorized information to one's partner (intentionally or not) by the manner and intonation in which one makes one's bid. A bidding box is typically a plastic box with two slots, each containing a set of bidding cards. One slot contains 35 cards with symbols of bids (5 denominations—clubs (), diamonds (), hearts (), spades (), and notrump (NT)—in seven levels of bidding,
Vickrey auction is dominated by the strategy of truthfully bidding. The strategy of underbidding is dominated by bidding truthfully. Assume that bidder i bids formula_8. If formula_9 then the bidder would lose the item with a truthful bid as well as an underbid, so the strategies have equal payoffs for this case. If formula_10 then the bidder would win the item either way so the strategies have equal payoffs in this case. If formula_11 then only the strategy of truthfully bidding would win the auction. The payoff for the truthful strategy would be positive as they paid less than their value of