[wbartley]

IMP game. Human South.

---

Forget about South's bid. That's just me goofing around. The 2NT call was described as one might expect - balanced invite; 11-12 HCP. The 4NT was describe as quantitative and invitational to 6NT. Now, I challenge anyone to come up with a better hand that matches North's bidding to this point - Qxx in spades, 3 card support for both of partner's suits and 12 solid high card points. I'm wondering whether it's possible to construct a hand where GIB bids 2NT and accepts an invitation to 6NT.

[smerriman]

4NT appears to be an impossible bid where the description has been pieced together from other auctions.

A quantitative invite to 6NT opposite 11-12 would require 21 points; your 1♠ bid limits you to 18, and it can't combine 18- and 21. It tries to by saying both 18+ HCP and 18- total points in the description, but it's not possible to have a hand which accepts opposite 18.

[wbartley]

Your explanation makes sense. I've always been a bit perplexed by the disconnect between GIB's bidding explanations and GIB's actual bidding logic. Normally when a bid is undefined, and by undefined I mean that no followup rules are in place to deal with it, GIB simply repeats the previous description. But this time it indicated that 4NT was an invitation to 6NT. Perhaps there is no disconnect. It doesn't decide whether to go to slam based on the quality of it's own hand relative to its own bidding to this point but combines its assets with those previously advertised by me and can't get to 32 or 33 "points" or whatever it needs.

In the human bidding world, if I were North and my partner invited me to slam, I might wonder how he/she managed to dredge up a slam invitation after having only bid 1S initially but I would bid 6NT in any case because there's no point in being overly pedantic. My partner heard my bid and presumably knows that it was merely invitational to game. If I go down in 6N I won't be ashamed to show my hand.

I'm of the opinion that 1♦=1♥=1♠ will be passed about as often as a reverse, that is to say, only when partner has a sub-minimum 1♥ response with three spades - the same sort of hand one would have to pass a reverse. I will pass 1♦=1♠=2♥ if my hand is Qxxxx Qxx x xxxx. There's no way I'm passing an opening bid of 1♦ with this hand and I have no qualms about passing 2♥. I did some simulations where I examined sub-minimum responses to a 1♦ opening holding 4+ hearts and 4 spades and it was wrong to pass 1♠. With, Qxxx Qxxx x xxxx, it turns out that it's correct to raise to 2♠ after 1♦=1♥=1♠.

What's the point of all this? I think the upper limit of 18 "points" for the 1♠ bid is too low. There's no reason to consume bidding space by bidding 2♠ with mild distribution since your partner will only pass 1♠ with a sub-minimum and 3 card support.

[steve2005]

North could have shape other than 4333.
This is worst shape possible and I usually deduct 1 point for this shape.
So, if North was 4432 or 5332 it would be better.