Editing User:Brian/Bridge/Subsequent bidding after major suit agreement

After a major suit fit has been found, the partnership's primary objective is to explore the possibility of game (and possibly slam). A number of ways in which agreement is shown have been collected in this page, along with the subsequent bidding conventions.

==Raises to 2M==
After a major suit has been bid at the 1 level and raised to the 2 level (showing 3+ card trump support with 6&ndash;10 points), subsequent bids have the following meanings:
* Pass is to play (showing a minimum).
* A suit below 3M may show interest in either game ''or'' slam.
:* With invitational strength (game interest), it shows a weak 3+ card side suit and asks partner to raise to 4M with either a maximum or less than 2 losers in the bid suit.
:* With slam interest, the help-suit bid is an artificial relay, and asker will bid again after the 3M or 4M response. Asker's rebid is a [[User:Brian/Bridge/Control bidding|control bid]] or [[User:Brian/Bridge/Blackwood|Blackwood]] (see also [[User:Brian/Bridge/Responding to Blackwood|responses]])
* 2NT shows invitational strength with balanced distribution, asking partner to choose between 2NT (pass), 3M, 3NT, or 4M.
* 3M is invitational to game, showing 16 to 18 declarer points and asking responder to raise to 4M with 9+ support points.
* A suit above 3M but below 4M is a [[User:Brian/Bridge/Splinter|splinter]]. Any subsequent bid outside the agreed major is a [[User:Brian/Bridge/Control bidding|control bid]] or [[User:Brian/Bridge/Blackwood|Blackwood]] (see also [[User:Brian/Bridge/Responding to Blackwood|responses]]).
* 3NT shows balanced distribution and game-forcing strength, and asks partner to choose between 3NT (pass) or 4M.
* 4M is a sign-off.
* 4NT is [[User:Brian/Bridge/Blackwood|Blackwood]] (see also [[User:Brian/Bridge/Responding to Blackwood|responses]]).

==Jacoby 2NT==
The Jacoby 2NT response (alertable) is used only by an unpassed hand and in the absence of interference. It shows 4+-card support for opener's major, balanced distribution, and game-forcing strength with slam interest. Opener's rebids are:
* 3 of a side suit shows a void or small singleton
* 3M shows a balanced maximum (19&ndash;21 total points)
* 3NT shows intermediate values with a balanced distribution (16&ndash;18 total points)
* 4 of a side suit shows a good 5+ cards in the side suit
* 4M shows a balanced minimum (15&minus; total points)
After hearing about opener's hand, responder can either sign off in the major, bid a side suit to show a [[User:Brian/Bridge/Control bidding|control]], or bid 4NT, [[User:Brian/Bridge/Blackwood|Blackwood]] (see also [[User:Brian/Bridge/Responding to Blackwood|responses]]).

==Raises to 3M==
Invitational raises to 3M occur in sequences similar to the following:
* 1&hearts; (P) 3&hearts;
* 1&clubs; (P) 1&spades; (P) 3&spades;
* 1&diams; (P) 1&hearts; (P) 1&spades; (P) 3&spades;
* (1&spades;) 2&hearts; (P) 3&hearts;
* (1NT) 2&spades;* (P) 3&spades;

Note that a raise of a weak 2M opening or a weak jump overcall is NOT invitational; it is a sign-off.

After hearing a 3M invitational raise from partner, subsequent bids are as follows:
* Pass is to play (showing a minimum).
* 4M is to play (showing a non-minimum but lacking slam interest).
* A bid in a side suit is a [[User:Brian/Bridge/Control bidding|control bid]], showing slam interest.
* 4NT is [[User:Brian/Bridge/Blackwood|Blackwood]] (see also [[User:Brian/Bridge/Responding to Blackwood|responses]]).

==Raises to 3NT==
In the following sequences, the 3NT response '''shows''' 3-card support for the major, with a balanced distribution and 13 to 15 HCP:
* 1M (P) 3NT
* 1M (X) 3NT
:* With no support, responder redoubles first and then rebids 3NT.

Opener's rebids are:
* Pass, to play. Shows a balanced hand with little or no ruffing potential, where 3NT and 4M will likely result in the same number of tricks.
* 4M, to play. Shows a hand with some ruffing potential, where 4M will likely take more tricks than 3NT.
* A bid in a side suit is a [[User:Brian/Bridge/Control bidding|control bid]], showing slam interest.
* 4NT is [[User:Brian/Bridge/Blackwood|Blackwood]] (see also [[User:Brian/Bridge/Responding to Blackwood|responses]]).

However, in the following sequences, 3NT '''denies''' 3-card support for the major and is to play:
* 1&hearts; (1&spades;) 3NT
* 1&spades; (2&hearts;) 3NT
* 1M (2m) 3NT
:* With support, responder would cue-bid the enemy suit instead.

==Conventional limit raises following interference==
The sequences
* 1M (X) 2NT*
* 1M (1NT) 2NT*
* 1&hearts; (1&spades;) 2&spades;
* 1&spades; (2&hearts;) 3&hearts;
* 1M (2m) 3m
show invitational or greater strength, and at least 3-card support for opener's major. Opener rebids 3M with a minimum, or 4M with a non-minimum. Responder can raise 3M to 4M with game-forcing strength.

==Interference after agreement==
The subsequent bidding structures shown above assume no further interference after agreement. If interference does occur '''after''' agreement, subsequent bids have the same meanings as they would without the interference, but sometimes the opponents will be able to prevent you from communicating enough information to reach the optimal contract for your side. Also, sometimes you might need to sign off in 5 of your major to bid over the opponents. For example:
* 1M (P) 2M (4m) ?
:* You have no way of showing invitational strength. You can still raise to 4M despite not knowing whether partner has a maximum, but it's risky.
* 1&hearts; (1&spades;) 2&hearts; (4&spades;) ?
:* Now you obviously can't bid 4&hearts;, but you can consider bidding 5&hearts;. Doubling for penalty is also an option (it can't be misinterpreted as takeout since your side already has an agreed major). Factors to consider include: whether you think 5&hearts; is making, whether you think 4&spades; is making, how many tricks you think 5&hearts; is going down, how many tricks you think 4&spades; is going down, and vulnerability.
@@ Line 31: / Line 31: @@
 * (1NT) 2&spades;* (P) 3&spades;
-In the following sequences, the raise to 3M is '''not''' invitational, but is instead preemptive:
+Note that a raise of a weak 2M opening or a weak jump overcall is NOT invitational; it is a sign-off.
-* (1&clubs;) 1&hearts; (P) 3&hearts;
-* 1&spades; (2&diams;) 3&spades;
-* 1&hearts; (1NT) 3&hearts;
-* (1&clubs;) 2&hearts; (P) 3&hearts;
 After hearing a 3M invitational raise from partner, subsequent bids are as follows: