[Bbradley62]

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Why doesn't East want to just defend 2♥? Why does South's first redouble show 25+? Nice spade stopper, West. North sure is bidding a lot on his 1-count with singleton support.

[barmar]

GIB's rule for penalty doubles is if they're bidding your biddable suit, and your side has at least 21 HCP and no fit, double them. If your suit is rebiddable, you can do it with 19 HCP; 17 HCP with a twice rebiddable suit, and so on (subtracting 2 HCP for each increase in suit quality). However, other rules (e.g. bidding game) may take precedence. It prefers to have shortness in opener's suit, and claims that it has at most 2, but will double with 3 if there's nothing better to do.

GIB's rule for penalty redoubles is: if he hasn't limited its hand to below game values, then the partnership has enough for the 4 level (suggesting slam if partner has extras he hasn't shown yet); if he has limited its hand, it shows a max for the previous bidding. So in this case, since North has shown 0, and South hasn't limited his hand, the redouble shows 25+. That's why North keeps bidding -- it thinks the partnership has enough for game, so it bids it.

West's book bid on the 4th round is 3♦, but sims told it that its half stopper is good enough for NT. Since North can't have much strength, either East will have some ♠ help, or the suit will block.

[xxhong]

This rule for penalty double is ridiculous.
Penalty double is usually a matter of level. Against 7 level contracts, trump A would be enough.
Against one level contract, it's simply crazy to make a penalty double with only a biddable suit.
The basic bridge logic for penalty double is that you have a reasonable chance to defeat the contract and you are unlikely to do better if you declare (Also, opps are unlikely to find a good spot at higher level).

Also, the condition for 2H is simply wrong. It can't be unlimited. 2H should be a limit bid with about 11-18 HCP, with good (long) suit and (or) good shape.

Also, the rule for redouble is ridiculous. The correct logic for redouble is that the chance to make the contract against a known bad distribution is reasonably good.

barmar, on 2012-February-09, 12:11, said:

GIB's rule for penalty doubles is if they're bidding your biddable suit, and your side has at least 21 HCP and no fit, double them. If your suit is rebiddable, you can do it with 19 HCP; 17 HCP with a twice rebiddable suit, and so on (subtracting 2 HCP for each increase in suit quality). However, other rules (e.g. bidding game) may take precedence. It prefers to have shortness in opener's suit, and claims that it has at most 2, but will double with 3 if there's nothing better to do.

GIB's rule for penalty redoubles is: if he hasn't limited its hand to below game values, then the partnership has enough for the 4 level (suggesting slam if partner has extras he hasn't shown yet); if he has limited its hand, it shows a max for the previous bidding. So in this case, since North has shown 0, and South hasn't limited his hand, the redouble shows 25+. That's why North keeps bidding -- it thinks the partnership has enough for game, so it bids it.

West's book bid on the 4th round is 3♦, but sims told it that its half stopper is good enough for NT. Since North can't have much strength, either East will have some ♠ help, or the suit will block.

[ahydra]

Isn't 2H normally artificial on this auction, showing a strong hand with S and D? Aside from that, both redoubles by the "human" were ridiculous, although the 4H bid isn't exactly textbook.

As for how GIB should interpret the redouble, nothing wrong with "I think 2H is making", surely? If the first redouble shows enough to make 4H, then the second redouble shouldn't show any more given we're now at 4H.

ahydra

[barmar]

xxhong, on 2012-February-09, 15:27, said:

This rule for penalty double is ridiculous.
Penalty double is usually a matter of level. Against 7 level contracts, trump A would be enough.
Against one level contract, it's simply crazy to make a penalty double with only a biddable suit.

There's more to it than the simple explanation I gave. Higher priority rules can take precedence, preventing it from making penalty doubles when there are better things to do. Also, the description I gave is only for the 4 level and below.

Quote

The basic bridge logic for penalty double is that you have a reasonable chance to defeat the contract and you are unlikely to do better if you declare (Also, opps are unlikely to find a good spot at higher level).

Sure, it's easy to say that, but turning that into bidding rules that just look at points, shape, and suit quality is difficult. The rules also force simulations, they're supposed to help it judge better.