Slam seeking convention

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 the denomination mentioned). However, even natural systems such as Acol find occasional need to resort to artificial means called conventions. A very common type of conventional bid is of the slam-seeking variety to be used in situations when a small slam or a grand slam appears possible but more information is needed before the optimum contract can be determined.

In order to make a small slam (grand slam) the combined strength and shape of the two hands must be sufficient to take 12 (13) tricks and the opponents must not be able to cash two (one) tricks before declarer has set up those 12 (13) tricks. It is widely considered (for example Klinger 1994 and Root 1998) that 33 high-card points are needed for making a small slam in no trumps, and 37 high card points for a NT grand slam. However, slams in a suit can be made with fewer high-card points if the two hands fit well, for example have no "wasted values", have a double fit (8+ cards in both trump suit and a side suit), have "primary values" (aces and kings) rather than "secondary" ones (jacks and queens), or are shapely (with long suits and voids or singletons). Slam seeking conventions have been devised to establish whether these conditions exist.

There are pros and cons with each convention and none are suitable in all circumstances; some are better used when a notrump contract is likely and others when a trump contract is sought. Certain groups of slam seeking conventions can be used in combination whilst others are mutually exclusive. The choice of conventions and their application to particular hands is a basic part of bridge skill.

In its original form, Blackwood is an artificial four notrump bid (4NT) which asks partner to disclose the number of aces in his hand. With no aces or four, partner replies 5♣; with one, two, or three aces, 5♦, 5♥, or 5♠, respectively.

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