This article is intended only as a brief overview.
The "system" described as 2-over-1 game-forcing refers to the following 6 bids :
1 - 2
1 - 2
1 - 2
1 - 2
1 - 2
1 - 2
When responder uses a game-forcing "2-over-1" bid he is informing opener that he, too, holds at least opening-bid values. Accordingly, the partnership may leisurely proceed to the optimum contract without fear of being dropped below game. Opener then should show his "shape," without implying # of HCP. I recommend to just "dive in." The finer points can be learned as you go.Try answering these questions and just assume "natural" with no science needed (other than that the 2-over-1 response has forced the partnership to game). From the answers, you can learn what the bids mean.
As opener, what do you rebid?
ANSWERS (with further clarification)
A) 2. Repeat the 6-card suit. Opener's first obligation is to show shape. Repeat a 6+ card suit regardless of HCP strength. Even with another ace, the rebid is 2 with 6+ hearts.
B) 3. Forcing, of course—until at least game is reached. This says nothing about HCP.
C) 2. Natural again – and just coincidental that you have extras. This bid would be made if the A were a low diamond.
D) 2. Natural. Don't jump with extras. Don't rebid notrump with a singleton. Slam exploration can come later; for now, look for the trump suit (or notrump).
E) 2NT. Natural—also, not promising extras.
F) 3. An unnecessary jump should show a solid suit. Jump rebids don't promise anything other than a solid 6+ card suit (such as AKQJxx or KQJ10xx).
In the auction below, you are the responder. Again, you can just follow the guideline of "bid naturally."
What is your second bid with each hand below?
H) 3. Forcing, of course. Stronger than jumping to game. In 2/1 GF auctions, a jump to game in a previously bid suit is the weakest action. It is an attempt to sign off and not look for slam.
I) 3. No need to rush into Blackwood.
J) 4. Jumping to game is weaker than staying low with 3 (as in example H).
K) 4NT Quantitative (4 would be Gerber--ace-asking).
An important part of the 2/1 GF system is to employ a 1NT bid (by an unpassed hand) in response to a major-suit opening bid as forcing (or semi-forcing) for one round. Unlike Standard American, this bid is not limited to 6 to 9 HCP. Normally, it shows 6 to 12 HCP. More on this can be found here.
2-over-1 is game-forcing as long as responder is not a passed hand and there is no interference bidding (so, in competition, 2/1 is NOT game forcing).
The 2/1 Game Forcing system is really an outgrowth of Standard American and 5-card Majors and many of the methods and conventions employed are alike. There are more details—this mini-lesson is intended only as a brief overview of the principles. Also, more details are in "Larry Teaches 2/1 GF."
A 2-over-1 game force is not alertable.
The 1NT response is announced (by the opener) as "Forcing" or "Semi-forcing" -- whatever the partnership has agreed.
Yes, 1-2 should be played as GF. If faced with a choice between responding in a 4-card major or a 4-card minor (with enough for game), I recommend responding in the minor (to get into the comfortable 2/1 GF auction). You can always find the major later-there will be a later.
BMS 2/1 Webinars by Michael Berkowitz
updated: Feb, 2016