Control-showing bids are an extremely effective tool accurate slam bidding. Instead of finding out how many aces your partner has, you can use control-showing bids to figure out exactly which aces he posesses, as well as kings and other controls. This is often necessarry to find a good slam.
Controls. A control is a holding in a suit which prevents the opponents from taking quick tricks in the suit:
As a rule:
With most hands, it is much more important to know about your partners controls than about his aces. This is why good bridge players use control-showing bids instead of Blackwood for most slam auctions.
After a trump suit is agreed, you may sometimes bid a new suit to show a control. In particular:
EXCEPTION: If the trump suit is hearts, a bid of 3 spades can be control-showing.
EXAMPLES: All of the following bids are control-showing:
|1 ||3 ||4|
|1 ||3 ||3|
|1 ||1 ||3 4|
|1 ||1 ||2 3 4|
|1 ||2 ||2NT 4 5|
What Does it Show? In general, the initial control-showing bid shows slam interest and first-round control of the bid suit.
Responding. After your partner makes a control-showing bid, you should obey the following rule:
Note that the bid of 4 does not deny having first-round control of hearts. It simply communicates an unwillingness to participate in slam exploration. After responder bids 4, opener can always insist on a slam attempt by making another control-showing bid.
After the initial control-showing bid, both partners usually begin showing controls up-the-line. For example, consider the auction:
|1 3 4 5 6|
The 4 bid is an initial cuebid, showing first round control of diamonds and denying first-round control of clubs. (With club control, opener would have bid 4 instead.) The 5 bid shows-first round control of clubs, and denies having first-round control of hearts. (With heart control, responder would bid 4 instead.) At this point, opener decides to sign off in 6. (Apparently this was all he information he needed.)
Second-Round Controls. There are two situations under which you may show second-round control:
1. In the auction:
|1 3 4 4 4 · · ·|
the 4 bid shows second-round control of spades. With first-round contol, opener would have bid 3 initially.
2. In the auction:
|1 3 4 4 5 · · ·|
the 5 bid shows second-round control of clubs (since opener has already shown first-round control) and denies having second-round control of spades. Responder should probably signoff in 5 at this point unless he has a spade control.
Suits Bid by Partner. When your partner bid a suit, you may cuebid it to show either first or second-round control. Furthemore, since partner probably has length and strength in the suit, you should not cuebid your partner's suit to show shortness.
|1 1 3 3 4 4: Shows the Ace or King of diamonds.|
Returning to the Trump Suit. A return to the trump suit is always a signoff attempt. It commuticates the following message:
|"Partner, given the current information I am unsure about our slam potential. Maybe we should stop here."|
Your partner may then either pass or continue the slam exploration, taking your hesitation into account.
Late Control-Showing. When exploring grand slam, it is common to cuebid controls up to the 6-level or higher:
|1 1 2 4 5 5 5 6: Shows second-round control of clubs.|
If you run out of first and second-round controls, feel free to bid third-round controls!
Blackwood. Either partner may bid Blackwood at any time:
|1 1 3 4 4NT: Blackwood.|