Scoring context
The tables at right help to illustrate the limits of the scoring advantage to be gained in duplicate bridge by preempting or sacrificing when the opponents may be successful in making a game contract. The level to which one may preempt, bid competitively or ultimately sacrifice is heavily influenced by the vulnerability status of each side and the assumption that the defending side will double the contract. There are four possible scenarios: * Neither side is Vulnerable (equal vulnerability): The opponents are likely to score 400 or 420 points at game and a sacrifice bid which is defeated by no more than two tricks will lose at most 300 points. * We are Not Vulnerable and They are (favorable vulnerability): The opponents are likely to score 600 or 620 points at game and a sacrifice bid which is defeated by no more than three tricks will lose at most 500 points. * We are Vulnerable and They are not (unfavorable vulnerability): The opponents are likely to score 400 or 420 points at game and a sacrifice bid which is defeated by no more than one trick will lose at most 200 points. * Both sides are Vulnerable (equal vulnerability): The opponents are likely to score 600 or 620 points at game and a sacrifice bid which is defeated by no more than two tricks will lose at most 500 points. In summary, based upon the expectation that the opponents are likely to bid and make game, it is advantageous to preempt, compete or sacrifice for down three when vulnerability is favorable, down two when equal and down one when unfavorable.Preemptive openings
A preemptive opening bid is one made on the second or higher level, typically showing a weak hand containing a long, strong suit. Preemptive opening bids on the third or higher level are common for most bidding systems; for example, the hand of is a typical 3 opener. The bid is made on presumption that, without any additional tricks from the partner, at least six tricks can be taken with hearts as trump, and the potential penalty of 500 points in 3 doubled is smaller than the value or opponents' likely or . A preemptive opening bid usually shows at least six (6) high card points and a suit with six or more cards headed by honors (typically either K-Q or better or Q-J-10 or better) but less than a normal opening bid. Some textbooks recommend the "rule of 2 and 3":" Obviously, preempting at unfavorable vulnerability entails greater risk; such preempts, if ever, are often made with an intention of making the contract, and the long suit is often backed up by an unusual distribution, such as 7-4-2-0. An alternative approach is to bid the level suggested by the Law of Total Tricks, with the assumption that partner's hand has one third of the remaining trumps. Using this approach, * If playing "Preemptive overcalls
A preemptive overcall is a jump overcall (so 2 is preemptive over 1 but not over 1) that is otherwise identical to a preemptive opening bid. The suit requirements for preemptive overcalls are generally similar to a preemptive opening. However, they are normally loosened in third seat, when the partner has already passed, so the opening bidder can be sure that the only side preempted are the opponents, and thus can bid with better or thinner values.Other preempts
A partnership can preempt the opponents cooperatively, having discovered that they have an excellentResponses
Since the preempter has a weak hand, responder will pass most of the time. However, responder also has the following options: *Raise opener's suit: Usually done to further the preempt with 3-card support (or jump with even more support), making it even more difficult for the opponents to compete. However, a raise to game can also be made with a good hand without support for opener if responder expects to make the contract. Opener must pass after any raise by partner. *2NT: Asking to further describe the hand (forcing). Opener bids a feature or rebids their suit with no further information *3NT: To play. Responder expects to make 9 tricks either by running partner's suit or his own. If responder expects to run opener's suit, support is needed as opener may not have outside entries to his hand. Also, responder should have stoppers in all suits. *Bid a new suit below game: To play. Over a preemptive opening bid or overcall at the "two" level, many partnerships use the 2NT response to ask for more information about the preemptive hand. In the Standard American Yellow Card (SAYC) bidding system, the preemptive bidder responds by bidding another suit containing an ace or a king or, lacking such a suit, by rebidding the suit of the preempt at the "three" level. In either case, the responder can then place the final contract. The Ogust convention provides a more informative set of responses to the 2NT inquiry. * 3 shows a "minimal" preempt (typically 6-7 HCP) and a "poor" suit. * 3 shows a "minimal" preempt and a "good" suit. * 3 shows a "strong" preempt (typically 8-10 HCP) and a "poor" suit. * 3 shows a "strong" preempt and a "good" suit. * 3NT shows that the preempt suit is "solid" (headed by AKQ). The differentiation between "minimal" and "strong" preempts and between "poor" and "good" hands is a matter of partnership agreement, and typically depends upon the partnership's strictness in preemptive bidding. Partnerships that are very strict typically regard a suits with only two of the top three or three of the top four honors as "poor" while partnerships that preempt with poorer suits may regard such suits as "good." Hands that respond 3 or 3NT typically do not have outside entries, as their long suits contain nearly all of their high card points.The law of total tricks
Many players use the"In a competitive auction, it is safe to bid a number of total tricks equal to the number of trumps in the combined hands of both partners."When viewed in context of the Law of Total Tricks, normal preemptive opening bids, described above, basically assume that the preemptive bidder's partner possesses two of the five to seven outstanding cards of the long suit—mathematically, the "expected" number based on equiprobable distribution of the missing cards. Thus, the Law of Total Tricks implies that the preemptive opener's partner can safely raise the preemptive opening bid by the number of cards in excess of two in the named suit (for example, raise an opening bid of 3, which promises seven hearts, to 4 with three hearts (7+3=10 total tricks) or to 5 with four hearts (7+4=11 total tricks)), ''regardless of the responder's high card points''. The limit raises and preemptive raises of major suits in the Standard American Yellow Card bidding system also conform to the Law of Total Tricks. By opening a major suit normally, the opening bidder promises at least five cards of the major suit. A "limit" raise, which is a response of three of the opener's suit, requires ten to twelve high card points and four cards in the responder's suit, for a total of nine. Likewise, a preemptive raise, which is a bid of four of the opener's suit, requires five cards in that suit, for a total of ten. The Law of Total tricks allows the opening bidder to raise such responses by the number of cards in excess of five in that suit.
See also
*References
Further reading
* 290 pages. Second Edition 1996, Magnus Books. * 162 pages. Also: (1976) London: Robert Hale Books. . 162 pages. * Revised 1973, further revised 1991. * 59 pages. * 143 pages. * 162 pages. {{WPCBIndex Contract bridge bidding