Slam-seeking conventions Slam-seeking conventions Slam-seeking conventions are codified artificial bids used in the card game contract bridge. Bidding and making a small slam (12 tricks) or grand slam (13 tricks) yields high bonuses ranging from 500 to 1500 points. However, the risk is also high as failure to fulfill the slam contract also means failure to score the bonus points for a game (300-500). Conventions have been devised to maximise the opportunity for success whilst minimising the risk of failure. Contract bridge bidding systems are mainly "natural" (most bids have an obvious meaning) or "artificial" (many bids have a meaning unrelated to
History of contract bridge auction bridge made by Harold Stirling Vanderbilt and others. The most significant change was that only the tricks contracted for were counted below the line towards game and slam. That made bidding much more challenging and interesting. Another innovation was the concept of "vulnerability", a difference in the sizes of penalties incurred by partnerships that have or have not won one game. That discouraged sacrifice bidding to protect the lead in a rubber. Some other scores were adjusted to produce a more balanced game. Vanderbilt set out his rules in 1925, and within a few years contract bridge had so