Bridge & other card games/Bidding
QUESTION: North has 13 points,7D; 2S, 2H, and 2C
North opens the bidding with "1D"
South has 9 points: 4H, 4S, 4C, and 1D
South responds with "1H"
North now answers with "2D" and South answers "2S".
North ends the bidding by passing leaving South to play the hand in 2S and only 6 trump.
QUESTIONS: 1. since North had an unusual amount of diamonds [7 total], should the diamonds be rebid a 3rd time after South's "2S" bid? 2. is a change of suit by the responder forcing in the 2nd round of bidding or forcing only after the 1st round of bidding?
It would help if I knew the exact cards in each hand. However, in my opinion, the bidding through 2D is fine. South, however, has only 9 points. Furthermore, he can see that the hand is a misfit. North does not have support for any of South's suits and South has only a singleton in North's suit. Misfits generally do not play well and the partnership should tend to keep the bidding low. With only 9 points and no suit fit, South should pass quickly and be happy to play in 2D.
Bidding 2S seems to be pointless. What is South trying to accomplish? He doesn't have enough to look for 3NT and he certainly does not want to play in spades after North denied having 4 of them. The bid serves no constructive purpose and may lead to disaster. If North had rebid 3D over 1H showing a stronger hand, South certainly has enough to bid 3NT. However, after North only bid 2D showing a minimum opener, South would need 11 points or so to bid again, possibly bidding 2NT. With only 9 points, South should realize that his side does not have enough to make 3NT and that 2D is probably the best spot with North having a 6 card suit.
That being said, North should definitely rebid 3D over 2S. North should not expect South to have more than 4 spades. (If North had a double club stopper like ace-queen plus a diamond suit that was easy to set up like KQJxxxx then, over 2S, North could bid 2NT instead.)
If responder rebids a higher ranking suit as in the auction above, it shows at least an invitational hand and is forcing for one more round. If responder changes suit to a lower ranking suit 1D-1S-2D-2H, most people play that can be passed although some partnerships like to play that forcing. If opener had rebid 1NT, however, then 1D-1S-1NT-2H definitely should be passed (second suit lower ranking) while 1D-1H-1NT-2S is forcing for one round (second suit higher ranking).
---------- FOLLOW-UP ----------
QUESTION: Can you clarify the answer regarding opener's responsibility to continue bidding after his/her responder changes suits the first time and then again a second time? Is the opener ALWAYS required to continue the bidding if his responder changes suits the FIRST time? What circumstances [EX: the number of points in responder's hand, for example] change the requirement for the opener to continue bidding if his responder changes suits a second time?
Generally if responder changes suits a second time that bid is not forcing if the second suit is lower ranking than the first suit and the bidding is still not above the two level...1C-1S-1NT-2H can be passed by opener. Using the same reasoning 1D-1S 2D-2H can also be passed (although some partnerships prefer to play this particular sequence as forcing). Responder in these examples shows 6-10 points.
If the second suit is higher ranking than the first suit or else if it is at the three level then opener is forced for at least one round. For example 1D-1H-2D-2S or 1S-2H-2S-3C. Responder here shows 11 points or more.
If responder changes suit a third time and this is a completely new suit as opposed to just supporting a suit bid by opener, then this bid may or may not be forcing. If responder's second bid was not forcing (1C-1S-2C-2H) then the third bid can be passed (1C-1S-2C-2H-2NT-3D) since responder has the same weak hand that he showed after his second bid. However, if responder's second bid was forcing then the third change of suit would also be forcing.