[CSGibson]

I have some idea that the ACBL encourages declaring side to disclose negative inferences to the defending side after the auction but before the play, but can someone tell me if this is a voluntary disclosure of information or whether we actually have a legal responsibility to do so?

By negative inference, I mean things like "I had an opportunity to make a support double" or "our 1N rebid does not deny 4♠" or "our double in the auction 1C-(1H)-X is take-out, but denies 4 or more spades" - things of that ilk.

[mgoetze]

I don't know about the ACBL but I would expect all the things you mentioned to produce an alert when playing with screens in Europe. (In the support double case, alert the pass.)

[wank]

i would never alert the 1nt possibly having 4♠. that's just normal, no?

nor the lack of a support double. people support on 3, no?

[aguahombre]

wank, on 2012-March-13, 20:04, said:

i would never alert the 1nt possibly having 4♠. that's just normal, no?

Normal for a lot of pairs who don't care whether they play 1NT or 2S with a 4-4 fit. Normal for pairs who choose to add continuations to their checkback system after a 1NT rebid so that the 4-card spade holding by opener can be discovered.

For the rest of us, it is not normal. This creates, IMO, an interesting disclosure issue. I believe most experienced pairs know neither style is GBK or "normal".

[CSGibson]

mgoetze, on 2012-March-13, 19:56, said:

I don't know about the ACBL but I would expect all the things you mentioned to produce an alert when playing with screens in Europe. (In the support double case, alert the pass.)

yes, with screens its common to give the negative inferences immediately. I'm talking without screens.

[Vampyr]

wank, on 2012-March-13, 20:04, said:

nor the lack of a support double. people support on 3, no?

They don't if they are playing support doubles.

[campboy]

More to the point, an agreement that a 1NT rebid does not deny 4 spades isn't a negative inference. An agreement that a 1NT rebid did deny 4 spades would be a negative inference (he could have bid 1♠, but didn't).

If you do don't play 1NT as denying 4 spades, though, it is a 1♠ rebid which now carries a negative inference from the failure to rebid 1NT -- it (presumably) denies a balanced hand.

[WellSpyder]

campboy, on 2012-March-14, 04:14, said:

More to the point, an agreement that a 1NT rebid does not deny 4 spades isn't a negative inference. An agreement that a 1NT rebid did deny 4 spades would be a negative inference (he could have bid 1♠, but didn't).

If you do play 1NT as denying 4 spades, though, it is a 1♠ rebid which now carries a negative inference from the failure to rebid 1NT -- it (presumably) denies a balanced hand.

I think you mean if you DON'T play 1NT as denying 4 spades...

But you make an interesting distinction between what is a negative inference, and what is a (perhaps surprising) lack of a negative inference. One of these came up in a match recently, that I think is even clearer than the 1NT rebid issue, namely a 1NT response to a 1♥ opening. To most people, I suspect, this will tend to deny 4 spades (unless playing Flannery, perhaps). But we have a couple locally who play 5-card majors with a forcing NT response (not as common an approach in the UK as in the US, for example), who will often have 4 spades within their forcing 1NT response to 1♥. As far as I can tell their 1♠ response shows 5 "because they play 5-card majors" not because they play Flannery, which AFAIK they don't. To me it seems clear that any explanation of the forcing 1NT bid (which is alertable in England, not announced) should include the information that it doesn't deny 4 spades, but this suggestion is resisted by the couple in question and I'm not a TD so it isn't really up to me......

[campboy]

WellSpyder, on 2012-March-14, 04:44, said:

I think you mean if you DON'T play 1NT as denying 4 spades...

Oops, yes, thanks. I'll go fix the post.

In your forcing 1NT example, if the pair doesn't mention that it could have 4 spades if asked what it means then that's not full disclosure IMO. But that's because it's a very unusual method, and nothing to do with negative inferences.

[WellSpyder]

campboy, on 2012-March-14, 05:26, said:

In your forcing 1NT example, if the pair doesn't mention that it could have 4 spades if asked what it means then that's not full disclosure IMO. But that's because it's a very unusual method, and nothing to do with negative inferences.

Well, I thought it was the lack of a normal negative inference here that made it very unusual, but either way we agree about the need for disclosure.

[campboy]

WellSpyder, on 2012-March-14, 05:35, said:

Well, I thought it was the lack of a normal negative inference here that made it very unusual, but either way we agree about the need for disclosure.

Yes, that's true. I just meant that a very unusual lack of an inference should be mentioned whether or not that inference is a negative one.

[Cyberyeti]

mgoetze, on 2012-March-13, 19:56, said:

I don't know about the ACBL but I would expect all the things you mentioned to produce an alert when playing with screens in Europe. (In the support double case, alert the pass.)

I'm VERY surprised by this comment (unless you're suggesting only with screens).

1♣-1♥-1N not denying 4♠ and 1♣-1♥-1♠ guaranteeing 5 clubs I've NEVER seen alerted in the UK, they're just seen as perfectly normal, probably as normal as the alternatives. The corrollary to this is that the question is often asked specifically.

[campboy]

Cyberyeti, on 2012-March-14, 05:54, said:

1♣-1♥-1N not denying 4♠ and 1♣-1♥-1♠ guaranteeing 5 clubs I've NEVER seen alerted in the UK, they're just seen as perfectly normal, probably as normal as the alternatives. The corrollary to this is that the question is often asked specifically.

These are definitely not alertable according to EBU regulations. The first one because it is specifically mentioned, and the second because of the general principle that negative inferences alone don't make something alertable (OB 5G3l).

[aguahombre]

campboy, on 2012-March-14, 06:00, said:

These are definitely not alertable according to EBU regulations. The first one because it is specifically mentioned, and the second because of the general principle that negative inferences alone don't make something alertable (OB 5G3l).

There is nothing "negative" about the inference that a 1S rebid guarantees five clubs. It is a bid in one suit which also says something about another suit. Maybe such bids are not alertable in your jurisdiction; but, that is a general principle for alerting in mine.

The rebids after 1C-1D ---if 1M=unbalanced and 1N could have major(s) are alertable; it is hard to imagine why 1C-1H-1S unbalanced, and 1C-1H-1N bypassing, are not subject to the same requirements.

[campboy]

aguahombre, on 2012-March-14, 06:21, said:

There is nothing "negative" about the inference that a 1S rebid guarantees five clubs. It is a bid in one suit which also says something about another suit. Maybe such bids are not alertable in your jurisdiction; but, that is a general principle for alerting in mine.

It's negative in the sense that the reason you know he has an unbalanced hand is that he would have rebid 1NT with a balanced hand. The regulation in question says that having an agreement about other possible calls which affects this one does not make it alertable.

Quote

The rebids after 1C-1D ---if 1M=unbalanced and 1N could have major(s) are alertable; it is hard to imagine why 1C-1H-1S unbalanced, and 1C-1H-1N bypassing, are not subject to the same requirements.

They are not alertable in the EBU. They may be alertable where you are, but I made it clear I was talking about the EBU, and I was replying to a post in which Cyberyeti made it equally clear he was talking about the UK.

[aguahombre]

I was quoting what you posted for the context. The UK regulations are interesting, in that a bid of one thing which shows or denies another thing is apparently not alertable.

I probably shouldn't have replied at all about UK regulations in a thread started by Chris, who is in Oregon.

[iviehoff]

In just about any sequence of bidding there are negative inferences about what a player can't hold, which vary according to the bidding system. Do we alert everything because there is a negative inference the opponent, not knowing the details of my system can't work out although it is fairly obvious to me?

The fact that a modern Acol/weak player must hold 5 cards in his first named suit if he makes a rebid in a new suit at the 2 level started off as a negative inference, but then became such a useful understood feature of the bidding system that it is today seen as a requirement of the system.

One player has an agreement that he must have a 5 card suit to make a change of suit rebid, even at the one-level, and facilitates this by playing a 2C enquiry over the 1N rebid. Another player does not have this agreement. But can you really say that if he rebid 1N he never has a 4-card spade suit? Is the negative inference really available?

[CSGibson]

Stop hijacking my thread with discussion about the minutae of my examples, please. Does anyone actually know the answer to the OP?

[barmar]

campboy, on 2012-March-14, 04:14, said:

If you do don't play 1NT as denying 4 spades, though, it is a 1♠ rebid which now carries a negative inference from the failure to rebid 1NT -- it (presumably) denies a balanced hand.

In my case, I base my decision of whether to bid 1♠ or 1NT not just on the shape of my hand, but location of honors and maybe even table feel. I don't think my partner can quantify the specific hands where I bypass or don't bypass spades, the best I think he could say is that when I bid 1NT I could have 4 spades and a balanced hand. But if I bid 1♠ there's no expectation about the length of my minor -- it's a little more likely to be a real suit, but I don't think it's a big difference.

[mycroft]

What I can find in 10 minutes is this (from ACBL's Active Ethics pamphlet):

Quote

The actively ethical player will often go beyond what is technically required in volunteering information to the opponents. Quite often, the declaring side in an actively ethical partnership will volunteer such information before the opening lead is made. (But remember, when there has been misinformation given, such as a failure to alert or a mis-alert, there is a LEGAL obligation on the player whose partner misinformed the opponents. He, the bidder, must give the opponents the correct information at the end of the auction if his side is the declaring side or at the end of the play if his side is defending.)