Grand slam force Grand slam force The Grand Slam Force is a bidding convention in contract bridge that was developed by Ely Culbertson in 1936. It is intended to be used in cases where the combined hands of a partnership are so strong that a slam (winning at least 12 tricks) is a near-certainty and a grand slam (winning all 13 tricks) is a possibility. It allows one partner to gain information on the quality of trumps in the other partner's hand. When this convention is in force, a bid of 5NT (five notrump), when it does not conflict with other conventions used
Auction bridge Auction bridge The card game auction bridge, the third step in the evolution of the general game of bridge, was developed from straight bridge (i.e. bridge whist) in 1904. The precursor to contract bridge, its predecessors were whist and bridge whist. Auction bridge trick scoring, bonus scoring, and penalty scoring are radically different from contract bridge, and there is no concept of vulnerability in auction bridge. Bidding rules are nearly the same, although in contract bridge bidding many complex artificial bids and bidding systems have evolved. It is not certain to whom auction bridge should be credited. A letter in