In a partnership card partnership contract, the Blackwood convention is a popular bidder convention developed by Easley Blackwood. It was used to explore the ownership of the partnership of ace, king and in some variants, the queen of trump cards, to better assess whether a slam would be a good contract.
Two Blackwood versions are common: the "standard" Blackwood, developed by Easley in 1933, and Blackwood's "Roman Key Card" ( RKC or RKCB ), are named for the Italian team create it. Blackwood standards allow one partner to calculate ace and king partnerships in general. The key card variant is determined by certain "key" settings and allows counting trump and queen kings, as well as ace and king. Both versions are initiated by four notrump bids (4NT), and the entire convention family can be called Blackwood 4NT in both versions, or 4NT Key Card in the card variation key.
There are other 4NT conventions, such as Culbertson 4-5 Notrump, Norman Four Notrump, and San Francisco, but almost all bridge partnerships employ some Blackwood family members (who include Byzantium Blackwood) as part of their massacre investigation methods.
If the partnership's previous call is a natural bid in notrump, then 4NT is usually played naturally. More than the opposite difference is just a rise and a quantitative invitation to six notrumps, a small slam. More than four players who are intervened by opponents are usually played as competitive riders, expecting to play four notrumps. Such natural interpretations may apply at other auctions where previous partnerships have bid naturally or show a conventional hand balance. In some situations where 4NT is a quantitative invitation, especially where 4 ? is a leap, many partnerships use the Gerber convention instead of the Blackwood family: 4 ? asks the number of As cards or key cards.
Where both parties bid, 4NT is often played as a partner requesting a conventional takeout to help choose one of two or three suits, similar to a double-bottom takeout or a double-cuebid to double.
Video Blackwood convention
Standard Blackwood
Where the 4NT Blackwood standard applies, the four notrump bid (4NT) asks the partner to disclose the amount of the ace in his hand. Without an ace or four, partners answer 5 ? ; with one, two, or three aces, 5 ? , 5 ? , or 5 ? , respectively. The difference between no As and four cards is clear to Blackwood bidders (unless the partnership does not have a fourth) so that one member of the partnership knows the combined number of ace. That's often enough to set up a final contract. (The general agreement is that when the spade is not a trump suit 5 span title = "spades">? asks respondents to bid 5NT.It is useful when a 4NT reply goes past the intended trump suit but also indicates the slam is likely would be a bad contract because two aces are missing.)
The advanced bid of 5NT asks the number of kings corresponding to the same answer code at level six: 6 ? does not show king or four, etc. Asking the number of kings confirms that the partnership holds the four aces, so the partners can retaliate on level seven in hopes of taking thirteen tricks.
Vacancies may be as good as As's in some situations but should not be counted as an ace. Some experts (Kantar for one) recommend 5NT reply to 4NT - the cheapest without a standard defined meaning - to show a vacancy plus two aces and six of the lawsuits to show a vacancy in a bid suit plus an ace.
Maps Blackwood convention
Roman Blackwood
The standard Blackwood convention variety, known as Roman Blackwood , was popularized by the famous Italian Blue Team in the 1960s. In Roman Blackwood, his response was even more ambiguous, but more space saving. The basic response outline is:
In practice, ambiguity is impossible, since the power difference between the hands with 0 or 1 and 3 or 4 aces is large enough to be set in the previous bid round. In other words, a partner who has previously shown, for example, a high 12-15 point range is unlikely to hold 3 aces for his bid, etc.
Even the Roman Blackwood convention has several variations, ranging from about 5 ? and 5 ? responses. In all variants, they show 2 aces. One variation is that 5 ? shows extra value, while 5 ? is not. In other variations, response 5 ? - 5NT shows a specific combination of ace (same color, same rank, or "mix").
If the query partner ensures that all As cards are present, they can proceed as follows:
- 5NT is a Grand Slam power
- The first available offer that is not an agreed setting is Roman Blackwood for the king. Partners respond gradually, as above.
Blackwood Key Card (RKCB)
Roman Key Card Blackwood (RKCB) has replaced most of the standard versions among players of the tournament. It was developed from a variant of Roman Blackwood (see above). According to RKCB there are five equivalent key cards and not just four cards: the trump king is counted as the 5th key card. Key card replies to 4NT are more compressed than standard ones and they are also starting to look for queen of trump cards.
Although replies to 4NT are more compressed, it is almost always possible to conclude which number of keycards is correct: 0 or 3, 1 or 4, 2 or 5. The evidence for such inference includes all auctions as well as the number of key cards used by 4NT bidders.
5 ? and 5 ? replies with 2 or 5 key cards also reject and show queens trump, respectively. (Responder can also show an extra-long queen in a trump card, where an ace and a king might pull all the cards in circulation in a lawsuit.)
Fifth ? and 5 ? does not say anything about the queen or the extra length, but the 4NT bidder may ask about it using the cheapest offer other than five of the trump suit. The code for replies to "queen query" varies; the general rule is that the cheapest offer in the trump suit denies the queen or the extra length and other calls show it. An option is to call positive to show features, such as the king with that suit, and 6 of the trump suits can show the queen of the trump card without the outside king.
The Blackwood Roman Key Card is based on a trump suit, which determines which of the four kings and queens to be shown as key cards. Trump deal is not required. One general rule is that the final bid before the 4NT bid is a key setting, has no trump deal.
1430 RKCB
Some partnerships use club responses to show 1 or 4 and diamond responses to show 3 or none, nicknamed "1430" (incidentally scores to create vulnerable small releases in main settings), with the original version dubbed "3014" when the difference is required. To facilitate Queen Demand, an expert version has been developed, where "1430" is used by strong hands and "3014" is used by weak hands. There are specific rules that determine when the pen's hand is weak and when is strong.
Blackwood Cards (KCB)
The halfway house between standard Blackwood and RKCB is Keycard Blackwood. Again there are five key cards, including trump kings, but unlike RKCB, the trump card queen is not considered.
5? - 0 or 4 key cards
5 ? - 1 or 5 key cards
5 ? - 2 key cards
5? - 3 key cards
This is supported by Bernard Magee as being simpler for club players, as with RKCB players sometimes not sure if the partner holds 0 or 3 key cards, or 1 or 4.
Request a bid other than 4NT
Kickback
"Kickback" is an RKCB variant designed by Jeff Rubens in accordance with the principle of Useful space. Step response is equal to RKCB, but request does not have to be 4NT. Instead it is a 4-level offer just above the agreed trump suit; that is.:
The kickback has the advantage of saving the offer space and, especially for a small suit, providing security at level 5 if the required key card does not exist. Since the Kickback bid will be a control bid, 4NT is usually replaced as a control bid in that setting (for example, 4NT is a heart-control bid if the agreed trump setting is a diamond). The disadvantage is that in unintentional partnerships, there can be confusion, whether the offer is a Kickback, a control offer or a preference for different tensions:
East intended 4 ? as a Kickback, but the West thinks it is a secondary support for the heart, and decides to pass it to a minimum. As a result, a reasonable diamond grand slam missed.
An established partnership may have agreed that since the heart is not supported after the opening rebid, 4 ? is unlikely to show support, and should ace ask for a diamond.
Redwood
"Redwood" is a variation of Kickback that is only used when the minor suit is a trump card. The level 4 bid in the setting above the agreed trump setting is a card/key card and the name stems from the fact that this offer will always be a red suit:
4 ? - RKCB for clubs
4 ? - RKCB for diamonds
Once the key card has been identified, the next stage bid (other than trump card) can be used to request Kings.
One of the advantages of this approach is avoiding the potential misunderstandings that can occur when using Minorwood but one disadvantage is that it uses one more offer (than Minorwood) and may limit the offer later when requesting Kings or Queens.
Using "Redwood," the ace/key card requesting 4NT is still in use when the trump suit is primary (heart or spade).
Minorwood
"Minorwood" is a variation of Blackwood, where a small suit approved by a partner will be the trump card itself used as a key/ask card. The request will be at four levels. Therefore:
4 ? - RKCB for clubs
4 ? - RKCB for diamonds
One disadvantage of this convention is that partnerships must agree to lose a 4-level bid naturally or get a clear agreement on which sequence sought and which was a natural offer. The advantage of this approach is to save the offer space. For example, the use of Redwood reduces the risk of misunderstanding but uses one more bid and may limit the offer later when requesting Kings or Queens.
Blackwood Exceptions
Blackwood Exceptions or Voidwood . designed by Bobby Goldman in an attempt to resolve the situation when Blackwood-the questioner had a vacancy. In this case, he is not interested in the ace partner in an empty suit, because he already has first-round controls; partner ace will present the duplicated value in that case. It should be noted, however, that many players, even experts, refuse to play Blackwood Exceptions because of the potential for disaster to forget the agreement.
It's usually played as a Blackwood Key Card Key, with only four key cards: three Aces out of empty clothing and a King of a trump card. However, the requested bid is not 4NT, but the settings are empty - Voidwood is made by jumping at level 4 or 5 in the empty settings after a match is found, for example:
Bid 5 ? , 5 ? and 5 ? presents Voidwood, shows a vacancy in the bid jacket and asks for another key card. Her response, as in RKCB:
- first step - 0 or 3 key cards (1 or 4, if playing 1430)
- Step 2 - 1 or 4 key cards (0 or 3)
- Step 3 - 2 key cards without queen trump
- step 4 - 2 key cards with queen trump
Apps
When the Blackwood bidder has a vacancy, and the partner shows one or more but not everything is missing, the "asker" will not know if the partner's ace duplicates the empty settings (where it will not be very helpful) or includes the losers. For this reason the bid cues for explicitly displaying As cards, or Voidwood exceptions or conventions to request useful As cards, are used with vacant hands.
Often non-experts ask for an ace when they really need other information from partners, acting as if the convention was designed to ascertain whether the partnership holds all of four cards or five key cards. The basic aim is usually to distinguish between one and two deficiencies, because less two cards make a bad bet. In other words, ace and key-card ask conventions should normally be used by a member of a partnership that plans at least to contract for 12 tricks if no more than one ace or key card is lacking.
The simplest way to think about Blackwood is this: "I'm afraid we'll lose the first two tricks, if we bid slam, I can use Blackwood as a kind of insurance policy, to ensure that this will not happen." But Blackwood will not help if, because of the hand structure, there are several ways to lose the first two tricks. This only helps, for the most part, if the exclusive risk of losing the first two tricks is because the opponent is holding two cards that can be cashed. Of course, the opposition may hold an ace and a king of a side suit, and can slam the tricks out, resulting in a direct set.
Thus, a player must use Blackwood only when he can ensure that the partnership holds at least second round control in all settings (king or, if suit is found, single). Thus, Blackwood's request by a player who holds two fast losers in a side suit is a wild gamble, as it is still possible that the suit is not controlled by Ace or King.
For the same reason, it is generally wrong to use Blackwood with a void. This is not always true, but the basic rule is: Do not use Blackwood with emptiness unless you're really sure you know what you're doing, and why you're doing it. You may lose two aces, but your vacancy can offset the lack of one of the enemy's As cards. Thus, Blackwood will not tell you what you want to know: Are we at risk of losing the first two tricks? If your party has two aces and vacancies, then you are not at risk of losing the first two tricks, as long as (a) your emptiness is useful (for example, not duplicating the functionality of your own ace) and (b) you are not susceptible to the loss of two tricks first in the fourth lawsuit (for, for example, one hand of a partnership holding a single in that suit or a protected king, giving control of both sides of your side).
Other problems can easily occur when a minor is an agreed trump suit, or a key setting when no approved trump suit is reached. Replies to Blackwood can take a partnership past their agreed suit and going to the next higher level may be one of the tricks that is too high. In this case the experts agree to use the Kickback or Redwood convention to save steps and can stop at 5 ? or 5 ? . The alternative is to avoid using whatever type of Ace is requested and use an alternate gesture offer.
A further problem occurs when, after hearing his colleague's response, the player who made the 4NT bid wants to quit at 5NT - because this is a forced bid to ask Kings. The general agreement is that the first non-suit asks respondents to bid 5NT. Whenever the first non-suit is "queen ask", the next non-suit asks to bid for 5NT. This should be planned before as if there were no space partners who had to bid on a normally unshakable contract of dismantling.
See also
- Gerber convention
- The power of grand slam
- Norman four notrump
- Quantitative no trump bids
- San Francisco
- Habit of looking for slam
References
Further reading
- Ron Klinger works with Pat Husband and Andrew Kambites (1994). Basic Bridge: a guide for a good Acol and play offer . Victor Gollancz Ltd is working with Peter Crawley, London. ISBN: 0-575-05690-8
- Paul Mendelson (1998). Mendelson's Guide to Battle Offers . Colt Books, Cambridge, UK. ISBNÃ, 0-905899-86-5
- Ben Cohen and Rhoda Barrow, eds. (1967). The Bridge Players' Encyclopedia . Paul Hamlyn, London.
- William S. Root (1998). The ABC of Bridge . Crown Publishers, New York. ISBNÃ, 0-609-80162-7
- Eric Crowhurst and Andrew Kambites (1992). Understanding Acol: a good bidding guide . Gollancz works with Crawley, London. ISBN: 0-575-05253-8
- Kantar, Eddie (2008). Roman Keycard Blackwood, Last Word (5th ed.). Toronto: Press the Parent Point. ISBN: 978-1-897106-35-8.
- Blackwood, Easely (1949). Bridge Humanics, How to Play People and also Cards (1st ed.). Indianapolis: Droke House.
External links
- "Roman Blackwood Key Card" on Bum Bridge
- "Roman Key Card Blackwood" in Bridge Guys
- "Roman Blackwood" in Bridge Guys
- "Blue Team Roman Blackwood" in Bridge Guys
- "Blackwood Keycard Exceptions" in Bridge Guys
- Eddie Kantar offer tips
Source of the article : Wikipedia
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