Discussion:
Notrump stoppers in 2/1 sequences
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p***@infi.net
2016-08-13 15:45:12 UTC
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A partner loaned me a copy of Mike Lawrence's "Workbook on the Two Over One System". I'm finding that while I favor his general approach as compared to Hardy, I would bid many hands differently. His first example in Ch 3 concerns notrump stoppers:

1S-2H
2S-2NT
3NT

Opener has J9865 A2 AKJ 875 and avoided rebidding 2NT for lack of a club stopper. Looking ahead to responder's point of view, he gives a similar auction:

1S-2D
2S-3C

where responder has 42 965 KQJ106 AQJ. So apparently neither player will rebid notrump with xxx in a side suit, though Jxx may suffice. We can;t match those two hands up, but how about:

J9865 AQ
A2 KQ1074
AKJ Q65
875 963

Perhaps we should not be in game, but it doesn't seem practical to stop short. Although 3NT could be down on five or six club tricks off the top, mu guess is that 3NT will make more often than 4H or 4S, especially since no one overcalled in clubs. We could weaken either hand by a point and I still suspect 3NT will have better chances than a major.

Some questions, playing a 2/1 game force style with opener's rebid of his suit not promising six:
(1) Would you rebid 2NT or 2S as opener? (3D would show extras by agreement.)
(2) Assuming opener rebid 2S, what would you rebid as responder?
(3) After 1S-2H; 2S-2NT, what would you rebid as opener?

If anyone cares to run DD or SD simulations on the combined (West/East) hands with restrictions on North to reflect the lack of an overcall or takeout double, that would be appreciated.
P***@yahoo.com
2016-08-17 14:40:39 UTC
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Post by p***@infi.net
1S-2H
2S-2NT
3NT
1S-2D
2S-3C
J9865 AQ
A2 KQ1074
AKJ Q65
875 963
Perhaps we should not be in game, but it doesn't seem practical to stop short. Although 3NT could be down on five or six club tricks off the top, mu guess is that 3NT will make more often than 4H or 4S, especially since no one overcalled in clubs. We could weaken either hand by a point and I still suspect 3NT will have better chances than a major.
(1) Would you rebid 2NT or 2S as opener? (3D would show extras by agreement.)
(2) Assuming opener rebid 2S, what would you rebid as responder?
(3) After 1S-2H; 2S-2NT, what would you rebid as opener?
If anyone cares to run DD or SD simulations on the combined (West/East) hands with restrictions on North to reflect the lack of an overcall or takeout double, that would be appreciated.
The Lawrence / Hardy systems for 2/1 (Lawrence was consulted on Hardy's latest and best two-book series, Bidding for the 21st Century, which differs from Hardy's original book, and was written after Lawrence's workbook.) specifically prescribe a 2N rebid by the opener as having stoppers in the unbid suits. However, after the 2S bid in that system, 3S is bid ONLY with three spades according to them. So, the strict interpretation of that system would be for responder to bid 2N over 2S, whereupon the entire auction would be:

1S-2H-2S-2N-3H-3S-3N.
jogs
2016-08-17 21:04:33 UTC
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Post by p***@infi.net
1S-2H
2S-2NT
3NT
1S-2D
2S-3C
It's a lot harder to design an unbiased test than you think.
If the bidding starts
1S-2D
there are 3 possible continuations

1S-2D, 2NT Hardy 2/1
1S-2D, 2S Lawrence 2/1
1S-2D, 3D
All three sequences have flaws. But it is unavoidable. The hands are not ideal.

Any simulations must consist of underlying assumptions. It is possible that we would not agree on those underlying assumptions.
jogs
2016-08-17 22:41:49 UTC
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This is the classical testing hypotheses dilemma. The hypothesis is 'game makes'.
--In testing a hypothesis, you make a Type I error if you reject the hypothesis when it is in fact true. You make a Type II error if you fail to reject the hypothesis when the alternative against which you are testing it is true.

Bridge tend to bid all games which make 50% of the time. Many when playing imps and vul are willing to bid games which make 43% of the time. You need to decide for yourself where these percentage points are. There is no way to avoid both types of errors.
Post by p***@infi.net
J9865 AQ
A2 KQ1074
AKJ Q65
875 963
I'm bidding game from either side of the table. We only get to see one hand. Neither partner can know that clubs are xxx // xxx.
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