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
Contract bridge tricks taken, the contract, and various other factors which depend to some extent on the variation of the game being played. Rubber bridge is the most popular variation for casual play, but most club and tournament play involves some variant of duplicate bridge, in which the cards are not re-dealt on each occasion, but the same deal is played by two or more sets of players (or "tables") to enable comparative scoring. For competition level, so called IMP score is of high significance. One theory is that the name "bridge" has its origins in the name of an earlier game.