[lycier]

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Strangely,GIB raise 5♣ up to 6♣,it showed GIB North have extra values,but actually GIB north have showed its values completely after rebid 3♣,as for raising to 6♣,we find real values in a blue moon.

[Antrax]

Opposite ♠QJ ♥AKQJ ♦A ♣KQJ which is the hand you promised with your 5♣ bid more or less, North's spade singleton is what you're missing to bid 6.

[ahydra]

Antrax, on 2014-March-26, 04:00, said:

Opposite ♠QJ ♥AKQJ ♦A ♣KQJ which is the hand you promised with your 5♣ bid more or less, North's spade singleton is what you're missing to bid 6.

Is 4C not stronger than 5C here? (2S is GF.)

ahydra

[Antrax]

Dunno. I just read "no ♠AK, 21+ TP" in the 5♣ description.

[1eyedjack]

And yet, if GIB's judgement is purely TP-based, the previous 3C bid by North showed 12-18 TP, and he only has 13. I am surprised that North considered this sufficiently good a hand in context of what went before that he know reckons that he has extras.

I think that with the West cards I would not have contented myself with a simple 1S and thereafter shut up. I see the colours, but with a certain 7 tricks I think that at the table I would have popped in a 3S bid over 2S. Of course, if I did that opposite GIB, East will be bidding 4S.

[Antrax]

I don't understand why context matters. The hand I showed makes 6♣ cold. GIB knows that's what you're holding, because that's what the bid told it. Why on earth would GIB not bid the slam?

[1eyedjack]

Why would South not bid slam, if it is making opposite a minimum North?

[Antrax]

Dunno, better ask South. Do you really not understand how GIB works? Or do you expect BBO to herald a new age in computer AI?

[Bbradley62]

1eyedjack, on 2014-March-26, 09:46, said:

And yet, if GIB's judgement is purely TP-based, the previous 3C bid by North showed 12-18 TP, and he only has 13. I am surprised that North considered this sufficiently good a hand in context of what went before that he know reckons that he has extras.

North did not bid 6♣ based on his total point holding; he bid 6♣ because (based on the description provided for 5♣) he thinks South said "I have enough for slam opposite a minimum opening, except that I'm afraid we have two spade losers off the top". Since North has the needed spade help, he bid slam.
PS: I don't like the given description of 5♣, but that's different than blaming North for making an unreasonable bid.

[Stephen Tu]

Here I guess the main problem is 5♣ was poorly defined as being way stronger than necessary. 21+ total points, really, given a partner who opened?

In general GIB has a bad habit of raising 5m to 6m. There are two main scenarios:
- competitive auction, particularly after preempts. To a certain extent in these auctions one has to play partner to have around 7/8 pts or so, because there is no room really to find out and stay below game when he's totally broke, while still catering to getting to games where points are more evenly distributed among the partnership. So one is often justified in taking a stab at 5m with something worth around 20 total points even if partner actually might be broke. But GIB defines bidding minor game on one's own as 29 total points so it bids 6 on the values you were already hoping for.

- non-competitive auction, partner makes a bid of say 3m or some other bid which is limited in strength. Partner takes a stab at 5m, which he thinks is a good gamble, but is well aware might fail. Esp at IMPS vul where you might be going for a below 50% game. GIB bids 6 anyway. Really if one leaps to 5m bypassing 4m, this should be completely non-invitational to slam opposite a limited opener, just as 3nt is. If opener's range was still 12-18 and opener has 17, fine, but with the lower range opener should never try 6 like this hand.

Would be nice if these could be fixed.