[Bbradley62]

---

Given that 2N showed 8+, what would 3N have shown over 3♣?

[barmar]

3N would show: 2-5 C; 2-5 D; 2-4 H; 2-4 S; 8-11 HCP

The book bid is 6♣ -- there's a rule that says to try a 7-card fit even though the bid is supposed to show an 8-card fit. At IMPs, simulations are all over the place:
3 I bid 3H
2 I bid 3N
1 I bid 3S
1 I bid 6C
4 I bid 6N

MP is more consistent:
1 I bid 3H
10 I bid 6N

[Bbradley62]

barmar, on 2011-November-29, 11:14, said:

3N would show: 2-5 C; 2-5 D; 2-4 H; 2-4 S; 8-11 HCP

That sounds like a good description of North's hand, although I'd say it denies 5 (maybe even denies 4) clubs, but that's nitpicking. It also allows South to continue the auction appropriately.

I'm certainly glad that GIB ignores the "book" bid; 6♣ is atrocious.

[barmar]

The reason it doesn't say that it denies club is because there just a few generic default rules that say "If we have GF values but not enough to invite slam, bid 3NT"; we get to these if no more higher priority rules (e.g. the ones that say to show support for partner's suit) matched. GIB automatically refines its descriptions when a more specific bid is made, but it doesn't try to refine the descriptions based on all the bids that could potentially have been made but weren't.

And while the rule database could have separate rules matching different bidding sequences that lead to 3NT, so that we could distinguish the ones that include partner showing a long suit (so we're denying a fit) from the ones that don't (so we're not saying anything about a fit), it would complicate the rules for little gain.

[Bbradley62]

You took that whole answer to address my self-described nitpicky aside, but ignored the main question of why isn't it automatic to bid 3N over 3♣ when GIB's description of that bid so accurately describes his hand.

I guess I should have been more clear. I am not asking why GIB didn't make the obvious bid; I am requesting that you teach him to do so in the future.

[barmar]

I think I see the problem. There are rules that essentially say "If we have enough points for slam, and we can't show support below 3NT, bid the slam -- even if we have to play in a Moysian". And these take precedence over the default 3NT rule.

What's missing is that partner should already know that we have enough to investigate slam, because the 2NT bid showed it. We need to change the criteria for these rules to "We have enough points for slam AND more points than we've previously shown".

[Bbradley62]

Thank you.

[cloa513]

Why doesn't GIB bid 3♥ to show his four card major and allow for partner bid ♠ if he has it? Its all forcing to 3NT at least after all.

[barmar]

I think the change I suggested above would allow that as well. All the rules for these normal bids are currently being overridden by the rule that says to bid a slam if you have enough points.