The Culbertson 4-5 notrump is a slam-seeking convention in the game of

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 ...

. It was devised in the early 1930s 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 ...

. Most four-notrump conventions (

Blackwood Blackwood may refer to: Botany * African blackwood ('' Dalbergia melanoxylon''), a timber tree of Africa * African blackwood (''Erythrophleum africanum''), ('' Peltophorum africanum'') also Rhodesian blackwood, trees from Africa * Australian bla ...

and its variants being the best known) demand that bidder's partner define their hand using agreed codified responses. In contrast, the Culbertson 4-5 describes the bidder's hand, and invites partner to use their judgement in the light of that information.

Description

A bid of four notrump (subject to common-sense defined exceptions) shows either: * Any three aces, or * Two aces, and the king of any suit previously bid by either partner. In response: * A bid of five notrump shows either: ** Any two aces, or ** One ace, and the kings of all suits previously bid by either partner. * A bid of a new suit shows first-round control (ace or void) there, but is not compulsory with such a holding. * Six of a previously-bid suit shows a desire to play there (holding one ace, or the kings of all bid suits). * Five of the lowest-ranking suit bid by either partner is a conventional

sign-off A sign-on (or start-up in Commonwealth countries except Canada) is the beginning of operations for a radio or television station, generally at the start of each day. It is the opposite of a sign-off (or closedown in Commonwealth countries exce ...

, denying the values to make any of the stronger bids. If the four notrump bidder next bids five notrump, that shows all four aces. A bid of five notrump not preceded by four notrump shows three aces and the king of a bid suit. In subsequent bidding, common-sense rules apply.

History

Culbertson's proposal of this convention threatened to disrupt the publication of the 1935 version of the

Laws of Contract Bridge Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. It has been vari ...

. The Portland Club, guardian of the laws in England, considered it equivalent to playing with exposed cards. Noel Mobbs persuaded the Club that they were wrong. In his 1949 book ''

Design for Bidding ''Design for Bidding'' is a book by the Russian-born English bridge player S. J. "Skid" Simon, published posthumously in 1949. It is about the theory of bidding in contract bridge, particularly in the context of the Acol system of which Simon ...

'', "Skid" Simon called the Culbertson 4-5 "an adult weapon" and Blackwood "merely a nice toy". The Culbertson 4-5 has been superseded by Blackwood and other conventions, but was reported in 1967 to still be popular among some leading British players.

References

{{WPCBIndex Bridge conventions