This blog provides supplementary thoughts and ideas to the site. If you haven't seen the main site, there is a lot there including the Martel and Rodwell interviews, photos, and articles. This blog is focused on advancing bridge theory by discussing the application of new ideas. All original content is copyright 2009 Glen Ashton.

Sunday, November 22, 2009

Structure Revelations

As I mentioned in the last post, using the robots might be the fastest method of testing a new bidding structure or complete system. Last month I played thousands of hands where I opened 1NT, and the playtesting of the robots notrump structure had a couple of revelations.

I've been a big believer in responder showing the singleton/void to the notrump opener, but it surprised me the ratio of how many times that was useless to how many times it was useful. On the vast majority of hands that responder wants to get to game with, if there is no major fit the contact will be 3NT, and showing the singleton/void rarely changes that.

For hands without a four card major (4cM), the robot notrump structure has two common ways to show a singleton/void on the way to 3NT. These are:

1) Use minor suit Stayman (1NT-2S) with both minors, and then show a specific major suit singleton/void.
2) Transfer to the minor (2NT to Cs, 3C to Ds), then bid a new suit at the three level to show a specific singleton/void (there is no way to show long Ds, short Cs, no 4cM, at the three level).

From playtesting the structure, it would be better to give opener the opportunity to refuse to know the singleton/void and hand types. Let's remap the 1NT-2S response to be game forcing, no 4cM, and a hand with a singleton/void. Opener can rebid 2NT to learn about responder's hand type, or rebid 3C, which says not interested unless lots of extras in shape and/or points.

Here's the detailed structure:


2NT: what you got for me?
--3C: 6+Ds, any singleton/void. 3D asks shortness.
--3D: 6+Cs, major suit singleton/void. 3H asks shortness.
--3H/S: both minors, singleton/void in bid major.
--3NT: 6+Cs, singleton/void diamond.
-- 4C: 6+Cs, singleton/void diamond, good slam interest or better.

3C: not interested.
--3D: a long minor with any singleton/void, extra shape/values. 3H asks suit (3S=Cs, 3NT and above = Ds)
--3H/S: both minors and extra shape/values, singleton/void in bid major.
--3NT: to play

Based on playtesting many hands, most auctions will go 1NT-2S(GF, no 4cM, singleton/void any suit);-3C(not interested)-3NT.

This frees up the sequences 1NT-minor transfer then new suit bids, which can be employed in various ways. One thing that is missing from the above use of 2S, compared to the robot structure, is the good slam tries with no singleton/void (1NT-minor transfer and then 3NT is a mild slam try). These could be implemented via the minor suit transfer:

1NT-2NT(transfer to Cs);-3C-?
--3D: good slam try in Cs, no void and often no small singleton
--3H: slam try with both minors, no void and often no small singleton
--3S: slam try with both minors, excellent clubs

1NT-3C(transfer to Ds);-3D-?
--3H: good slam try in Ds, no void and often no small singleton
--3S: slam try with both minors, excellent diamonds

Likewise the sequences showing 4-4-4-1s/5-4-4-0s (no 5cM) by bidding 1NT-3D, 1NT-3H, or 1NT-3S to show the shortness are a waste of time - using Stayman works almost all the time. After Stayman finds no major fit, if opener has a 4cM opposite a major suit singleton 3NT is usually as good as spot as any, and if opener has denied a 4cM, bidding 3C/D with the longest minor can investigate the stopper situation.

One option is to play 1NT-3D as showing long clubs and a 4cM - over 3D opener can ask with 3H (3S=Hs, 3NT+ = 4Ss), bid 3S stopper showing, bid 3NT to play, or bid 4C forcing to 5C. Then 1NT-2C;-2D-3C shows an unspecified singleton/void in any suit but clubs - 3D would ask, while 3NT would unask - that is opener does not want to know what it is.

The other revelation from playtesting was in competitive sequences, where we open 1NT, and an overcall is made directly before responder's first bid. Using Lebensohl many times shows that it is folly for responder, with a weak hand and a long suit, to be unable to immediately bid the suit.

For example in standard Lebensohl: 1NT-2S(overcall)-2NT(Lebensohl)-3S;-?. Opener will want to compete opposite some hands, safely pass in others, and double with good spades and no fit for responder. All that is impossible when opener does not know responder's suit, if any, for the Lebensohl bid.

Note that most partnerships now use "system on" after the 1NT-2C overcall, and thus we will just consider when the overcall is 2D, 2H, or 2S.

There has been increased use of Rubensohl (spelled various ways), and Transfer Lebensohl to allow responder a way to immediately show a suit. The basic format is:

2NT: transfer to Cs, to play or game forcing
3C: transfer to Ds, to play or game forcing
3D: transfer to Hs, to play or game forcing
3H: transfer to Ss, to play or game forcing
3S: transfer to 3NT, with no stopper in opponent's suit
3NT: to play with at least a partial stopper in the opponent's suit

If a suit could have been bid naturally at the two level, the transfer at the three level shows at least invitational values. A transfer to their known suit is game forcing Stayman, and if opener bids the transfer suit it denies a stopper.

Here's a more detailed discussion:

A version called Rumpelsohl has this main twist: 2NT, the transfer to clubs, is either clubs or a game invite in any non-club new suit that could not be bid naturally at the two level. For example 1NT-2S(overcall)-2NT(transfer to Cs)-P;-3C-P-3H is a game invite with 5+Hs.

I prefer invites to have some direct bid, and to lose the invite if unavailable. This is like Rubensohl as described above, but with this switch:

1) A transfer to their suit is a natural invite
2) 2NT, the transfer to clubs, followed by 3D is game forcing Stayman, and then bidding their suit denies a stopper.

For examples:

1NT-2S(overcall)-3H: invite with 5+Hs.

1NT-2S(overcall)-2NT(transfer)-P;-3C-P-3D: Stayman.

--Double: partnership option (penalty, negative, optional, values etc.)
--2S: natural, 5+Ss, non-forcing
--2NT: transfer to Cs, could be Stayman if next bid 3D
--3C: transfer to Ds
--3D: game invite in Ds
--3H: transfer to Ss, game invite or better
--3S: transfer to 3NT, no stopper
--3NT: to play, at least a partial stopper

It would be neat to reprogram the robot notrump structure to try this out.



  • At 12:27 PM, Blogger Memphis MOJO said…

    I'm enjoying this series. The main difference I've found from what you did, is that it's almost always right (after opening NT and hearing Stayman from the bot) to bid my major, even with 5. I get raised way more than half the time.

  • At 2:16 PM, Anonymous Mikey1nt said…

    Very interesting results. I've always thought showing shortage over 1NT is best method as well so I am surprised at how little difference it makes. I assume the simulation used a strong NT, I would think a weak NT would get a larger difference as the weak NT has more holes on average. You don't say what the actual difference is? Great analysis - thank you for sharing.


Post a Comment

<< Home