[1eyedjack]

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MP, Instant, 35

North clearly, and correctly decided that he was worth more than 2S over the double. So why sell out to 3C?

[lycier]

1eyedjack, on 2016-March-28, 04:13, said:

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MP, Instant, 35

North clearly, and correctly decided that he was worth more than 2S over the double. So why sell out to 3C?

" Not good " topic since Gibs have no human emotion, just like Google AlphaGo.
Here I replayed your hand by my basic Gib.

1- A normal Gibs' sequences

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Result : 3♦E=

2- My best bidding sequences

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Result : 4♠N+1
However judgement is very important, facing to invitational 3♠, my bidding troubles are
- Pass says " No suitable call-- 3-5♣, 2-♦, 3-4♥, 3-4♠, 13-15TPs. "
- 4♠ says " 3-5♣,2-♦, 3-4♥, 3-4♠, 16+hcp, 17-20TPs."
So pass should be a normal bidding.

3- My best bidding sequences

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Result : 4♠S=

4-

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Result : 3♠N+2

5-

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Result : 3♠N+2

6-

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Result : 3♠N+2

7-

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Result : 4♠N+1

My final conclusion is your advanced Gib went wrong within a unknown reason. Of course, I am a layman, just saying.

[iandayre]

1eyedjack, on 2016-March-28, 04:13, said:

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MP, Instant, 35

North clearly, and correctly decided that he was worth more than 2S over the double. So why sell out to 3C?

Your point is very valid. To me system is partially to blame. I don't like to have to go through 2NT to show this hand. A direct 3S should show invitational values with 5 or more trumps. This way gives the opponents extra space with little upside.

[iandayre]

[quote name='1eyedjack' timestamp='1459160033' post='880315']

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MP, Instant, 35

delete duplicate

[lycier]

Unfair comments above.
Obviously Gib CC has no problem on Lebensohl 2nt in this point, after 2nt, rebid-3s for invitation is a normal contract.
We should know Gib CC is only as a public system, not as a distinctive personal system. I think this problem is that for an unknown reason in fact, not for Gib CC.

[1eyedjack]

Leb in advance of X is useful if your suit ranks lower than opener's. Perhaps less necessary if the suit ranks higher. But I reckon that if you are going to use it for the benefits of the lower ranking suits it is simpler to adopt it in entirety.

[iandayre]

1eyedjack, on 2016-March-29, 06:09, said:

Leb in advance of X is useful if your suit ranks lower than opener's. Perhaps less necessary if the suit ranks higher. But I reckon that if you are going to use it for the benefits of the lower ranking suits it is simpler to adopt it in entirety.

I have played Leb in its entirety with human partners, in more detail than GIB does. I play 2NT then 3S here to be invitational with exactly 4 trump. This is how it was written up years ago. I haven't seen a detailed writeup recently.

[steve2005]

Ok Systematically Gib has decided this is worth an invitational bid. So, it starts with Lebensohl intending to bid 3♠.
But there is further interference and there is no entry in Gib's bidding system. So, Gib has to make a bid on it's general principle. I am surmising that Gib doesn't meet the requirement's for a 3♠ bid at this point.

This sort of situation arises in other situations. The one I find most embarrassing is with 6 minor and 5 major Gib opens 1m planning on reversing but latter doesn't have enough to make a reverse and the major suit is lost.

[Bbradley62]

steve2005, on 2016-March-29, 22:11, said:

I am surmising that Gib doesn't meet the requirement's for a 3♠ bid at this point.

What would 3♠ mean over East's 3♣ other than "I would have bid 3♠ over South's 3♣"?

[steve2005]

Bbradley62, on 2016-March-30, 21:01, said:

What would 3♠ mean over East's 3♣ other than "I would have bid 3♠ over South's 3♣"?

For a human this would be true.
to put it in chess terms 3♠ has to be in the opening book (or convention book) in this sequence. It is not!
So, Gib determines what 3♠ means in competition just like any other competitive hand. It does not get the use of the Lebensohl convention after interference.

[1eyedjack]

Bbradley62, on 2016-March-30, 21:01, said:

What would 3♠ mean over East's 3♣ other than "I would have bid 3♠ over South's 3♣"?

I would expect 3S to have the same meaning as without competition, except restricted by those hands for which pass would have been superior. North had no expectation of an opportunity to defend 3C at the point that he bid 2N. So, while he may have been committed to bidding 3S in the absence of competition over 2N, it is at least in principle feasible that it could judge defending 3C as better. I am not suggesting that it would be good judgement on this hand; it would not. But it is a judgement call that it should not dismiss without consideration.