[pescetom]

During a current bridgewinners discussion on UI explanation for beginners, Mike Ma gave the interesting example below. I'm sure he won't mind if I quote it here to ask for a clarification that would probably be superfluous to most there.

Mike Ma on bridgewinners, on 2018-May-01, 08:44, said:

1) advancer made a transfer bid of 3♥,

2) 2NT bidder did not know/forgot that was transfer, and "raised" to 4♥, not alerting/announcing transfer of course,

3) advancer now used UI of no announcement to know that partner missed the transfer, and 4♥ was meant to be natural raise, and not some kind of super-acceptance bid. He proceeded to tank and then bid 4♠.

4) Because of the tanking, 2NT bidder also has UI and knows his partner did not intend 4♠ to be QB for hearts, and that woke him up that 3♥ was a transfer. So he passed 4♠.

It was a club game. I did not care about adjustment. I did call the director so that these opponents could perhaps understand to avoid using UI in future. I pointed out that advancer should interpret 4♥ as if his partner had announced transfer. I also pointed out that overcaller should not use the BIT to interpret 4♠. The director basically said since advancer knew his partner misunderstood the 3♥ bid from the lack of announcing transfer, of course he should correct to 4♠.

I did not write to Flader. The overcaller did. Of course what he wrote was not so accurate about what happened. But he did say he forgot 3♥ was transfer.

Note that in point 2 he writes "know/forgot", but at the end he adds that the 2NT overcaller said that he forgot: so the agreement in place was to play transfers and the overcaller forgot this and raised what he thought was a suit.

What is not clear to me is why Mike pointed out to the Director that "advancer should interpret 4♥ as if his partner had announced transfer", implying that he had failed to do so. Attempting to ignore the UI deriving from the missing alert, I imagine advancer would assume that 4♥ is a control-showing cuebid with a super-accepting fit in ♠ : if so then surely 4♠ may be the only logical alternative if he has a weak hand?

[WellSpyder]

pescetom, on 2018-May-01, 09:28, said:

What is not clear to me is why Mike pointed out to the Director that "advancer should interpret 4♥ as if his partner had announced transfer", implying that he had failed to do so. Attempting to ignore the UI deriving from the missing alert, I imagine advancer would assume that 4♥ is a control-showing cuebid with a super-accepting fit in ♠ : if so then surely 4♠ may be the only logical alternative if he has a weak hand?

Yes, 4♠ may be the only LA if responder has a weak hand. But your original quote seems to imply that the TD said responder should always bid 4♠ because he knows from the lack of an announcement that partner hasn't correctly interpreted 3♥. That is clearly wrong, since as you correctly realise, responder isn't supposed to "know" that his partner misunderstood 3♥ at all.

[barmar]

One of the problems with examples like this is that novices often don't know anything about artificial super-accepts of transfers. So 4♥ is an "impossible" bid as far as they're concerned, and can only mean that partner misunderstood the attempt to transfer. Therefore, there may be no LA other than 4♠.

But the director's reasoning was clearly wrong. You can't make decisions based on your partner's failure to alert, you must actively avoid using that knowledge.

[pescetom]

barmar, on 2018-May-01, 13:44, said:

One of the problems with examples like this is that novices often don't know anything about artificial super-accepts of transfers. So 4♥ is an "impossible" bid as far as they're concerned, and can only mean that partner misunderstood the attempt to transfer. Therefore, there may be no LA other than 4♠.

But the director's reasoning was clearly wrong. You can't make decisions based on your partner's failure to alert, you must actively avoid using that knowledge.

I can handle super-accepts and control-bids in my sleep, it's just the UI laws that give me a sore head
Yes I can see that the Director was clearly wrong whatever was going on, and I'm reassured that I understood the advancer's lawful options. I'm still not certain about his partner though.

Let's assume that after the 4♠ bid, partner finally realised (due to advancer's tank or not) that he had misunderstood an attempt to transfer.
What are his lawful options now, assuming that 4♠ over a ♥ raise would be a control-bid?
Does he just have to continue bidding as if ♥ are agreed, no matter what?
Does it make any difference whether:
- he believes that transfer was not part of agreement and partner was mistaken
- he believes that transfer is part of the agreement and he had just forgotten that
- he isn't really sure if transfer is part of the agreement or not
?

[barmar]

What matters for the overcaller is whether there's UI along with advancer's 4♠ bid, and what that UI demonstrably suggests. If you don't think it suggests anything about whether the heart bid was a transfer, then overcaller can try to reach a conclusion based just on the bidding.

[blackshoe]

There are two parts to this: what can opener do in the bidding, and what legal disclosure obligations does he have?

Addressing the latter first:

If he believes that transfer was not part of agreement and partner was mistaken, he has no disclosure obligations.
If he believes that transfer is part of the agreement and he had just forgotten that, then he must, before the end of the Clarification Period (which ends when the opening lead is faced), call the Director and in the Director's presence inform the opponents of the problem.
If he isn't really sure if transfer is part of the agreement or not, same as immediately above.

All of this is independent of his obligations wrt bidding. For those, well, if it was some mannerism or other source of UI from partner that caused opener to realize he screwed up, then opener has UI on which he cannot act. So he has to treat 4♠ as some kind of slam try for hearts and bid accordingly. Signing off in 5♥ is the call second most likely to get him in trouble. The call most likely to get him in trouble is pass. But if he has a hand that would cooperate with a 4♠ slam try for hearts, he has to do that. If opener just suddenly woke up, and there was no UI from partner then in theory he can do whatever he wants. But good luck convincing the director there was no UI, especially with the opponents insisting there must have been, even if they didn't catch it at the time. "There must have been UI" is a bad basis for a ruling, but it will happen from time to time. IAC, if opener "just woke up" he would probably do best to call the director immediately, explain the failure to announce the transfer, and see what the director says. Not sure if adding "I don't think I have any UI" would help or hurt his case. Might depend on the director and/or how loud the opponents are — or who they are.

[pescetom]

barmar, on 2018-May-02, 08:37, said:

What matters for the overcaller is whether there's UI along with advancer's 4♠ bid, and what that UI demonstrably suggests. If you don't think it suggests anything about whether the heart bid was a transfer, then overcaller can try to reach a conclusion based just on the bidding.

Say that overcaller recognises that there is UI demonstrably suggesting that ♥ was bid as a transfer to ♠. And he now suddenly remembers clearly that the real agreement was to play transfers after an overcall. Does he still have to continue slam investigation in ♥ because Pass is demonstrably suggested by the UI, even though Pass is also suggested by inference from his agreements which he now remembers and are written on the CC available to opponents?

[barmar]

pescetom, on 2018-May-02, 09:01, said:

Say that overcaller recognises that there is UI demonstrably suggesting that ♥ was bid as a transfer to ♠. And he now suddenly remembers clearly that the real agreement was to play transfers after an overcall. Does he still have to continue bidding in ♥ because Pass is demonstrably suggested by the UI, even though Pass is also suggested by his agreements which he now remembers and are written on the CC available to opponents?

Although we've had some debates about this in the past, the general concensus is that once you start bidding based on a mistaken understanding, you're usually stuck with it if there's any UI that would wake you up. Even if the UI isn't what actually woke you up, your actions are constrained based on what the UI suggests.

Last week we had a rarity, an appeal of a UI ruling in our little club game. We had to make it clear to the offender that it doesn't matter whether she noticed her partner's hesitation, and the ruling doesn't accuse her of intentionally taking advantage. Once the UI is out there, we rule as if she could have noticed it and what actions it suggests.

[pescetom]

Thanks to all for the helpful comments, that is a lot clearer now.