Slam-seeking conventions are codified artificial bids used in the

card game A card game is any game using playing cards as the primary device with which the game is played, be they traditional or game-specific. Countless card games exist, including families of related games (such as poker). A small number of card ga ...

contract bridge Contract bridge, or simply bridge, is a trick-taking card game using a standard 52-card deck. In its basic format, it is played by four players in two competing partnerships, with partners sitting opposite each other around a table. Millions ...

. 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 system A bidding system in contract bridge is the set of Glossary of contract bridge terms#agreement, agreements and understandings assigned to Glossary of contract bridge terms#call, calls and sequences of calls used by a Glossary of contract bridge te ...

s 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 Acol is the bridge bidding system that, according to ''The Official Encyclopedia of Bridge'', is "standard in British tournament play and widely used in other parts of the world". It is a natural system using four-card majors and, most commonly, ...

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 Optimum contract and par contract are two closely related (and sometimes confused) bridge scoring terms in the card game contract bridge. Optimum contract The optimum contract is the one that offers the best chance of gaining the most scoring poin ...

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.

Blackwood

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. In a more modern form, known as Roman Key Card Blackwood (RKCB), the 4NT bid asks partner to disclose the number of key cards held where the five key cards are the four aces and the king of trumps. Responses are stepwise: 5 for 0 or 3 key cards, 5 for 1 or 4, 5 for 2 without the trump queen, 5 for 2 with the trump queen. Some prefer to reverse the meaning of the first two responses and the variants are referred to in abbreviation as RKCB 3014 and RKCB 1430 respectively. Various methods are used to continue with king-asking and queen-asking bids.

Gerber

This is similar to Blackwood but the ace-asking bid is 4 rather than 4NT. The responses are 4 for 0 or 4, 4 for 1, 4 for 2, and 4NT for 3. Similarly, a 5 bid following an ace-ask asks for kings. Gerber is a jump bid to 4 used after a notrump opening bid and on other occasions by partnership agreement.

Culbertson 4–5 NT

Culbertson 4–5 NT was the first slam bidding system to gain widespread approval; it was part of the Culbertson system through the 1930s, and was part of the British

system for many years. After suit agreement, the bid of 4NT showed two aces and the king of a (genuine) bid suit, or three aces. Responder would make one of these bids: five of the lowest bid genuine suit to deny an ace; bid a suit (if necessary at the six level) to show the ace of that suit. Bid 5NT to show two aces. There are various subtleties, and both partners are allowed some latitude for judgement. The convention is rarely used today.

Quantitative notrump bids

These are used to establish whether two relatively balanced hands have sufficient high card points (HCP) to make a

slam Slam, SLAM or SLAMS may refer to: Arts, entertainment, and media Fictional elements * S.L.A.M. (Strategic Long-Range Artillery Machine), a fictional weapon in the ''G.I. Joe'' universe * SLAMS (Space-Land-Air Missile Shield), a fictional anti-ball ...

grand slam Grand Slam most often refers to: * Grand Slam (tennis), one player or pair winning all four major annual tournaments, or the tournaments themselves Grand Slam or Grand slam may also refer to: Games and sports * Grand slam, winning category te ...

contract in notrump; used after a notrump opening bid.

Cue bid

Cue bids are a co-operative system. Cue bids are used to communicate specific controls (aces or voids, kings and singletons). Once a trump suit has been agreed and the two hands are considered to be strong enough, partners bid the lowest available suit which they control; this process continues until one of the partners has sufficient information to make the contract decision. Cue bids have been part of the

system from the early days.

Grand slam force

The grand slam force uses a direct bid of 5NT to query the quality of partner's trump suit. It cannot be used following Blackwood because the bid of 5NT asks for kings, but it can be used following cue bids or Gerber.

Splinter bid

Splinter bids are a variety of cue bids. Splinters are used early in the bidding to communicate a strong hand, with a fit for partner's last bid suit and a side-suit singleton or void. The splinter bid is a double jump shift to the singleton or void suit. Partner of the splinter bidder will then typically bid game or proceed with cue-bids to investigate the possibility of a slam.

Swiss convention

In the Swiss convention, in response to an opening 1 or 1, a bid of 4 or 4 shows four-card support for partner's suit, about 13–15 points, and two or three aces respectively. Alternatively, the bids of 4 and 4 can be used to show trump quality; the specific meaning of the two bids varies between partnerships.

Asking bid

Given a hand which justifies slam exploration, an Asking bid pin-points a potential weakness. As in Blackwood, one partner takes control and asks the other for his holding, but as in cuebids, it is related to a specific suit. The partner replies stepwise to communicate features of the queried suit. Asking bids were devised by

Alan Moorehead Alan McCrae Moorehead, (22 July 1910 – 29 September 1983) was a war correspondent and author of popular histories, most notably two books on the nineteenth-century exploration of the Nile, ''The White Nile'' (1960) and ''The Blue Nile'' (196 ...

and developed by

Ely Culbertson Elie Almon Culbertson (July 22, 1891 – December 27, 1955), known as Ely Culbertson, was an American contract bridge entrepreneur and personality dominant during the 1930s. He played a major role in the popularization of the new game and was wide ...

and are an alternative to cuebids. They are still used in some artificial systems, such as

Precision Club Precision Club is a bidding system in the game of contract bridge. It is a strong club system developed in 1969 for C. C. Wei by Alan Truscott, and used by Taiwan teams in 1969. Their success in placing second at the 1969 Bermuda Bowl (and Wei's ...

Serious 3NT

A "Serious 3NT" is used by one partner during a cue bidding sequence to indicate a strong slam try. A cue bid that bypasses 3NT indicates a control while denying a strong hand (in case partner is strong).

Last Train

A bid just below game level, in an agreed suit, suggests the possibility of a slam.

Relay bid

Relays form a highly artificial codified scheme, where one partner takes full control early in the auction and just bids the cheapest available bids (relays), and the other describes distribution and controls in detail. The scheme based on relays, where one partner describes an absence of controls (rather than presence, as in cue bids), is known as Spiral scan, and can be combined with Blackwood, even in natural systems.