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Experimental investigation of the definition on forcing 1NT.

#1 User is offline   lycier 

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Posted 2016-May-21, 07:49

Occasionally I met a bad hand played by human, this hand caught my attention, here is the hand diagram.



Result : 3E-2
We know that south should cuebid 2 normally instead of pass. But I am surprised to see its forcing 1NT. So I would decide to make several experimental investigation of the definition on forcing 1NT.

***************** When with 3-card support :
- Hand-1

Result : 4E-1
Even west Gib has only 3hcp, but it responds forcing 1nt due to 6TPs with 3-card support.
3 says 3,6+hcp", obviously this is a helpless lie, where is 6hcp in its hand?

- Hand-2

Result : 4E-2
This hand would prove that even west Gib has only 4hcp, but it responds forcing 1nt due to 5TPs with 3-card support.
Same fortune, 3 is a helpless lie.
- Hand-3


This hand would prove that even west Gib has 3-card support, it can't respond due to only 4TPs.

*********************** When without 3-card support :

- Hand-4


-Hand-5



-Hand-6


Even west Gib has 5hcp,8TPs, it doesn't respond.

- Hand-7



Now you see that west Gib would respond forcing 1nt eventually with 6hcp



My conclusion :
The golden standard definition of forcing 1NT are :
- When with 3-card support, it only shows "3-,, 5+TPs,forcing".(It has nothing to do with HCP - TPs is preferred.
- When without 3-card support, it only shows "3-, 6+HCP, forcing".(It has nothing to do with TPs - HCP is preferred.

Existing problems :
- TPs with shapes is not necessarily more bigger than hcp in the some situations.
- The developers are a bit superstitious on Total Points evaluation.

It is appreciated if you would point out my wrong.
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#2 User is offline   Stephen Tu 

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Posted 2016-May-21, 09:03

It is a fairly common human tactic to respond forcing nt with 4-6 and 3s. The idea is it obstructs opps better than passing, and the preference to 2s shouldn't be encouraging to partner because he is supposed to assume 2s. Harder for opps to balance because don't know you have 8cd fit or not.

The problem I think is GIB does not handle split ranges in bid definitions well. 2s really should be 2s, 6-9, OR 3s, 4-6. When it says 2-3S, 6-9, does east still generate hand with 9 hcp and 3s for West? Really it should pass that hand, not bid 3s.

First hand posted, clearly West should change original plan of 2s when partner rebid clubs and just pass.

Next hand, I thought GIB used to do transfers here after the 2nt rebid but maybe I remember wrong or it changed. In any case, it ought to have a way to sign off in 3s, e.g. 3s showing 6- total points, not 6+.

So if cannot solve these maybe better GIB pass these instead of include the weak raise in fnt like humans do.
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#3 User is offline   1eyedjack 

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Posted 2016-May-21, 09:38

I think that 3S is a poor choice by East, given that West has not promised primary support. I prefer 2N or 3C.
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#4 User is offline   lycier 

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Posted 2016-May-21, 09:48

3 is a helpless choice when it is in the unbalanced hand because Gibs never play wolff signoff convention which is a expert bidding tools.
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#5 User is offline   Stephen Tu 

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Posted 2016-May-21, 12:18

It is perfectly reasonable to have a system where the west hand bids 3s to sign off after 2nt. Hands without support can pass or bid 3nt. limit raise 3cd can bid 4S or 3nt depending on shape.

It is just the current definition is really bad. If it shows support it should be 6 or less, not 6 or more, and sign off.

Wolff isn't a convention typically used on this sequence. That applies to 1m-1M-2nt-3c, not 1M-1nt-2nt
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#6 User is offline   lycier 

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Posted 2016-May-21, 17:27

yes,yes, this comment is very correct.
In fact, many experienced experts would play transfer bid or Meckstroth adjunction after opener's rebid-2NT.
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