[Bbradley62]

What's with the explanation of South's double of 5♥? Why can't/doesn't it simply mean "I'm setting this, so this is a good place to be"?

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[S2000magic]

I don't see why it can't; I'd have taken it to mean exactly that.

[barmar]

See the GIB Bidding Explanation page. If a bid shows anything, it has to be in terms of the features described there: points, distribution, suit quality, etc. There's no way to represent "I think we're setting this", other than by saying that we have lots of points.

The book bid with the North hand is Pass, but simulations told it that slam was likely. It correctly figured out that South has a 2-suiter in ♠+♦, but it thinks you're much more solid. For example:

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[Bbradley62]

On the hand in OP, South passed 4♠ rather than investigate slam after North showed 8+. Hitting 5♥ in the next round of bidding should show a preference to defend; saying that it shows 25-31 is inconsistent with the prior pass. I don't think the hand you show would have passed 4♠.

[barmar]

North never showed 8+ points. His 4♠ showed 8- points. From South's perspective, North could have a Yarborough and a bunch of spades for that bid. His second double shows a bigger hand than he previously showed, but not enough to bid on opposite that. Meanwhile, North is at the top of his range for his bid, and both his honors are likely to work well.

I think the auction did confuse GIB a bit. EW have shown 20 combined points, South's first bid showed 18 points and second one showed even more, and North has 8 points (which he's never shown). There aren't enough points in the deck without extreme distribution.

BTW, the South hand doesn't match GIB's expectations for doubling and bidding.

[xxhong]

This hand is quite impossible. It is a 3H bid over 2H to show hands like this I think. So x then 2S should be a limit bid.

I think 5H should just say "I am defeating 5H if partner holds no much extra distributions".

 barmar, on 2011-November-29, 12:01, said:

See the GIB Bidding Explanation page. If a bid shows anything, it has to be in terms of the features described there: points, distribution, suit quality, etc. There's no way to represent "I think we're setting this", other than by saying that we have lots of points.

The book bid with the North hand is Pass, but simulations told it that slam was likely. It correctly figured out that South has a 2-suiter in ♠+♦, but it thinks you're much more solid. For example:

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[barmar]

 xxhong, on 2011-November-29, 15:48, said:

This hand is quite impossible. It is a 3H bid over 2H to show hands like this I think.

GIB doesn't know that convention (it thinks this cue bid just shows a game forcing hand with no suit to bid), but maybe we could add it.