[mink]

3♣ was not alerted by West. East alerted and explained both majors 5-5. West asked about North's double.

---

South knew the E/W partnership and was quite sure that 3♣ would show the majors. This was also stated in the E/W CC. So either West forgot to alert his 3♣, or he misbid, having forgotten the convention. South refrained from asking West about the bid as he feared the question might wake up West.

If West had bid natural clubs, North's double would be negative and show the majors. If West bid artificially, the double would show clubs. South decided to comunicate the latter meaning.

East could not make any trick, so he went down 9, 2600 for N/S. At the other table N/S also won all tricks, but the contract was 7♠ by South, 2210 for N/S.

When West became aware of what happened after the play, he felt that he was misinformed. Clearly his question about the double was asked in the context of his Clubs being natural. Therefore, the correct explanation should have been "majors" and not "Clubs". He had been strongly considering bidding 4♣, but finally did not dare as he was told that North held clubs.

What would have been the correct explanation for North's double under these circumstances?

If South did not know the meaning of 3♣, did not look at the CC and regarded it as natural, consequently explaining North's double as "majors", would this be the meaning of the call that West is entitled to know, or would it be a false explanation as there cannot be 2 different meanings of the same call?

This is an artificial case with a constructed hand, but somehow related to a real world case.

[axman]

The EW agreement to 3C was majors, and the NS agreement which is conditioned upon the EW agreement N's X was clubs.

axman

[pran]

 mink, on 2019-March-16, 12:00, said:

3♣ was not alerted by West. East alerted and explained both majors 5-5. West asked about North's double.

---

South knew the E/W partnership and was quite sure that 3♣ would show the majors. This was also stated in the E/W CC. So either West forgot to alert his 3♣, or he misbid, having forgotten the convention. South refrained from asking West about the bid as he feared the question might wake up West.

If West had bid natural clubs, North's double would be negative and show the majors. If West bid artificially, the double would show clubs. South decided to comunicate the latter meaning.

East could not make any trick, so he went down 9, 2600 for N/S. At the other table N/S also won all tricks, but the contract was 7♠ by South, 2210 for N/S.

When West became aware of what happened after the play, he felt that he was misinformed. Clearly his question about the double was asked in the context of his Clubs being natural. Therefore, the correct explanation should have been "majors" and not "Clubs". He had been strongly considering bidding 4♣, but finally did not dare as he was told that North held clubs.

What would have been the correct explanation for North's double under these circumstances?

If South did not know the meaning of 3♣, did not look at the CC and regarded it as natural, consequently explaining North's double as "majors", would this be the meaning of the call that West is entitled to know, or would it be a false explanation as there cannot be 2 different meanings of the same call?

This is an artificial case with a constructed hand, but somehow related to a real world case.

I assume that screens were used, I find no explicit remark to such effect?

West has no case:
South gave a correct explanation of the double based on his own knowledge of the E/W agreements (corroborated by the E/W CC).
He could only hope that North had received the correct explanation from East on the 3♣ bid so that South's explanation of the double indeed was correct.

(If the E/W CC had been incorrect so that the 3♣ bid indeed had been natural then the case would have been misinformation from E/W to N/S, not the other way round!)

edit: If South (without access to E/W CC) had explained the double as showing both majors then the missing alert would have been misinformation resulting in an adjusted score if N/S was "damaged"

[BudH]

The only reason for South to not explain North's double as negative (majors) was (1) knowing West wasn't showing clubs and/or looking at the convention card. (Did he look at the West's convention card after West's bid and North's bid?)

The large majority of the time, South would assume West's club bid was natural and therefore North's double would be explained as negative.

[pran]

 BudH, on 2019-March-16, 13:20, said:

The only reason for South to not explain North's double as negative (majors) was (1) knowing West wasn't showing clubs and/or looking at the convention card. (Did he look at the West's convention card after West's bid and North's bid?)

The large majority of the time, South would assume West's club bid was natural and therefore North's double would be explained as negative.

We have been told that South knew.
Therefore his explanation of the double was correct.

[steve2005]

Why are Ghestem type 2-suited bids forgotten so often?

[ahydra]

 pran, on 2019-March-16, 12:51, said:

I assume that screens were used, I find no explicit remark to such effect?

It's in the subtitle of the post.

Quote

Why are Ghestem type 2-suited bids forgotten so often?

I even saw Helness/Helgemo having a Ghestem mixup once (they didn't forget the bid was artificial, but forgot which two suits were being shown).

As a top English TD once said after we called him for "unauthorised panic" when a mixup occurred at our table and the 3C bidder then ran to 4C: "I had two suits, and I 'guessed 'em.'"

Quote

West has no case:
South gave a correct explanation of the double based on his own knowledge of the E/W agreements (corroborated by the E/W CC).
He could only hope that North had received the correct explanation from East on the 3♣ bid so that South's explanation of the double indeed was correct.

This is my view as well. Though I think South relying on his knowledge of the EW agreements is potentially dangerous, e.g. EW could have agreed that morning to switch 3C back to natural. He should have asked or checked the CC. Yes, this wakes up West, but West isn't allowed to take advantage of the wake-up anyway.

ahydra

[pran]

 ahydra, on 2019-March-17, 02:06, said:

[...]
This is my view as well. Though I think South relying on his knowledge of the EW agreements is potentially dangerous, e.g. EW could have agreed that morning to switch 3C back to natural. He should have asked or checked the CC. Yes, this wakes up West, but West isn't allowed to take advantage of the wake-up anyway.

ahydra

Yes, South could have been skating on thin ice, but what would have been West's position if E/W had changed their agreement but forgot to change the CC?

[barmar]

 pran, on 2019-March-17, 02:34, said:

Yes, South could have been skating on thin ice, but what would have been West's position if E/W had changed their agreement but forgot to change the CC?

I think if an opponent consults your CC, and it doesn't match your actual agreements, then you're guilty of MI, unless there's a jurisdiction that states that the only way to get information about the opponents' agreements is by asking them. I'm not aware of any such jurisdiction.

[helene_t]

 steve2005, on 2019-March-16, 15:46, said:

Why are Ghestem type 2-suited bids forgotten so often?

When you have a weak hand with long clubs, and you are the type of player who loves to preempt, and you play 3♣ as a natural preempt in other partnerships, then you just bid 3♣ without thinking twice. The opposite, that it is partner that forgets, happens less often.

What also sometimes happens is that partnerships change their agreement back and forth multiple times, and at some point one of them remember that they changed it recently but doesn't remember what they changed it to.

Once, in a team match, we thought we got a good score for collecting 1400 on a partscore board. Turned out our teammates had a Ghestem mix-up also so it was a wash.

[weejonnie]

Law 21 - No rectification or redress is due to a player who acts on the basis of his own misunderstanding.

I had a case today where declarer won a trick with ♥A and then said 'Jack'.

The Jack of hearts was in dummy - and so was the ♣J

Declarer's RHO played ♣Q and his LHO played ♥Q (which takes the trick)
RHO then led ♠6

[barmar]

 weejonnie, on 2019-March-17, 16:25, said:

Law 21 - No rectification or redress is due to a player who acts on the basis of his own misunderstanding.

Clearly if the opponent just assumes he knows your system, and he's wrong, that applies.

But if he consults your CC it's not his own misunderstanding, it's MI from your CC. The primary purpose of CCs is to disclose your agreements to opponents, an incorrect CC is as much MI as an incorrect verbal explanation.