[Codo]

We have no disagreement about your example Zel. 3 ♠ is a cuebid and a priori I would take it as strong with hearts. In my favourite partnerships it is exactly a better 4 ♥ raise, may or may not hold a spade control.

I just disagree with anybody ( Which is a bíg and convincing evidence that I am wrong...) that we just asume that these cases are comparable.

[mycroft]

I'll bid 2♠; I hope he gets what I mean.
Oh, he didn't Alert it; I bet he's taking it the natural way.
So I'll bid as if he has spades.
Now I have two options - I can bid 3NT, or I can bid my 6-card suit that I ostensibly showed 4 of, but I know partner thinks I have 0+ of. Which one is most likely to get me not playing some spade contract or "way too high, doubled"?

With screens, I think you have a case, because you can bid 2♠ and are allowed to guess that 3♠ is more likely a raise than a cue. Good luck getting out of it, but you can try. But that's where the Laws come in, and that's where "use the screen analogy" breaks down. With screens, you make the call and guess which way partner took it. Without screens, you make the call, and *know* which way partner took it. You can't just "bid what you would have", you have to "carefully avoid using the UI"; and in this case, 3NT is clearly not "carefully avoiding using the UI", because there is another reasonable call. It's just that that reasonable call is going to get you to 6♥x before partner is going to get the joke. (as it turns out, my guess is that it won't - see above - but oh well).

I appreciate the difficulty, but whether it's common or not, if it's legal without a suggested defence, and you didn't discuss it, that's your problem. Guess which way partner is going to play is fine. Guess, and use UI to try to recover is not.

[bluejak]

billw55, on 2012-December-04, 08:02, said:

Agree and I consider it too. Also I wonder about west's failure to bid 4♠. His previous raise to 3♠ clearly showed that he understood 2♠ as natural - what changed his mind?

Probably doubt. He thought but was not sure that 2♠ was natural. When, after raising, East bids 3NT, he is considerably less sure, and pass seems safest. Illegal? Only if he has UI suggesting it.

Codo, on 2012-December-04, 08:26, said:

How do you decide between these two cases:

1. East tried the STANDARD defence, get to know from the 3 Spade bid that West was not on the same wavelength and tried to save his side into 3 NT. West thought 2 Spades was natural, but with his balanced hand and his minor suit holdings over south and his help in hearts he thinks that 3 NT is the superior contract?
2. East tried something, got an UI from the missing alert and tried to rescue his side?

It is still allowed to try something at the table and to get to know that partner does not understand us. The OP wrote STANDARD DEFENCE for a reason. It is common bridge knowledge over there that 2 ♠ shows the other suits. And you are allowed to use your common bridge knowledge without an implicitly agreement. And it is allowed to use the brain over 3 ♠ and to change horses too.

So what is all this talking about UI really about? Which message does the UI of the missing alert creates which is not shown by the 3 ♠ bid?

There are many many cases where a player has both UI and AI suggesting something. How do you deal with it? You apply the Laws. When Law 16B says you may not choose amongst LAs one suggested over another by the UI, the Law makes no mention of AI. But AI affects what is an LA.

Codo, on 2012-December-04, 09:47, said:

Sorry, but both of you did not adress the main point:

1. Which information did the UI of the missing alert submit which was not submitted by the 3 ♠ bid itself?
2. Lets say, you play with screens, so you (East) do not know that West failed to alert. How would you take 3 Spade? I would KNOW that he obviously misunderstood my 2 ♠ bid and took it as natural. Are there any serious doubts about this?

Surely: if you bid 2♠ knowing for certain that it shows short spades, you would take a bid of the apparent opponent's suit as strong, forcing and artificial. You would not bid 3NT with a void.

So the UI suggests that partner's 3♠ shows spades rather than it is a cue-bid.