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,
Common value auction on. There are two bidders participating in a first-price sealed-bid auction for an object that has either high quality (value V) or low quality (value 0) to both of them. Each bidder receives a signal that can be either high or low, with probability 1/2. The signal is related to the true value as follows: This game has no SBNE in pure-strategies. PROOF: Suppose that there was such an equilibrium "b". This is a function from a signal to a bid, i.e., a player with signal "x" bids "b"("x"). Clearly "b"(low)=0, since a player with low signal knows with certainty