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The forcing notrump is a bidding convention in the card game of bridge. In Standard American bidding, the response of 1NT to an opening bid of 1 or 1 shows 6 to 9 high card points and is ''non-forcing''. Opener, with a balanced minimum, may pass the 1NT response and, if the opponents also pass, that will become the contract. A partnership may agree that this bid is ''forcing'' for one round; if the intervening opponent passes, opener must bid at least once more. This guarantees the responder at least one more opportunity to bid or pass. This mechanism allows the partnership to use the 1NT response for a greater variety of hands: in particular, ''invitational'' as well as ''minimum'' responder holdings. The forcing notrump is used over major suits only; 1NT is always standard and non-forcing over the minor suits. A bid of 1 forcing notrump shows 6 to 12 HCP, denies the ability to make a single raise (but not necessarily an invitational raise), and denies holding four spades if the opening bid was 1 heart. As the forcing notrump creates problems of its own, a popular variation that overcomes these is the forcing next step. ==Opener's rebid== Opener is forced to bid again: *2 of original major shows a six-card suit *2 of a lower-ranking suit shows a second suit (which of necessity may be short - see below) *2NT is natural and invitational (showing about 18 HCP) *3 of a new suit (jump shift) is natural, normally agreed to be game-forcing, and shows about 19 points or more When opener does not have a six-card original suit nor a four-card lower-ranking second suit, she will have to bid a short suit. Normally, she bids her three-card minor. If she has three cards in both minors, she bids 2 clubs. If opener holds exactly four spades, five hearts, two diamonds and two clubs (and thus originally opened 1 heart), she bids 2 clubs (a two-card suit!). There is no point in showing the spades, because responder has denied holding four spades (having skipped the 1 spade response to bid 1 notrump). After a 1 spade opening, however, there is no distribution that would compel opener to rebid a two-card suit. Some partnerships agree not to rebid a 2-card suit, preferring to promise 3+ cards. This allows responder to pass with 0,1 hearts and 4+ clubs. Instead, these partnerships rebid 2 (violating rule #1), or pass (if playing Semi-forcing notrump.) The forcing next step variation (discussed below) overcomes these problems by allowing opener to show a balanced hand, or any second suit and guarantee 4 cards in it, yet still offer the option of playing in 2 of the major. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「forcing notrump」の詳細全文を読む スポンサード リンク
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