Illegal convention

[barmar]

I think you misunderstood AH. The CPU is the negative inferences available when the illegal agreement is not used. The opponents will not be aware of these inferences, even if they would be aware that the illegal agreement is illegal. Especially then, because these people would assume that the opponents are not using an illegal agreement.

How is that specific to using an illegal system? Aren't there also negative inferences available from not using legal conventions? And unless your opponents know your system as well as you do, they may make assumptions that lead them to make incorrect inferences.

 

Suppose ACBL decides to move Precision from GCC to Mid-Chart. The next day, you start playing with the same Precision CC you were using the day before, and you alert everything exactly the same. You're not concealing anything, so how could the fact that it's an illegal system make it a CPU? The inference that 1-level openings are limited to 15 HCP is still available.

[Trinidad]

Why would you look for it? Do you have time before every 2-board round for a thorough reading of your opponents' convention card? That's great but most people don't.

Oh, so now the fact that you can't bother to look at something that is right in front of your nose, and meant for you to look at, means that an opponent has concealed something? I don't think that that is what "concealed" means...

 

As an aside, for every unknown opponent I check:

• basic system
  
• the section headed by "Yoohoo, opponents! This is where the odd stuff is!" (okay, usually it is phrased in more formal terms)
  
• leads and signals
  

This rarely takes more than 5 seconds and if it does then it was good that I looked. :) Usually, I have checked the convention card, and sorted my cards, ready to play, long before my opponents have decided who deserves the blame for the previous board. :( So one could say that I didn't have anything better to do, anyway.

 

If they would play something illegal, it will typically be on the convention card in the "Yoohoo, opponents!" section. So, it isn't necessary to make a thorough study of the convention card. A cursory glance will be more than enough.

 

Rik

[mycroft]

How is that specific to using an illegal system? Aren't there also negative inferences available from not using legal conventions? And unless your opponents know your system as well as you do, they may make assumptions that lead them to make incorrect inferences.

 

Suppose ACBL decides to move Precision from GCC to Mid-Chart. The next day, you start playing with the same Precision CC you were using the day before, and you alert everything exactly the same. You're not concealing anything, so how could the fact that it's an illegal system make it a CPU? The inference that 1-level openings are limited to 15 HCP is still available.

I was going to argue the other half of Vampyr's statement, but this does apply as well.

 

Is it a CPU that we don't/can't divulge the negative inferences from our highly unusual, but legal system? If it is, then the disclosure procedures are fundamentally broken (and yes, they are; we can't, completely, especially if never asked anything, make clear the negative inferences of partner's EHAA pass on her future bidding, for instance. But to nail an illegal system as CPU as well as illegal, where a legal system would not be so nailed, isn't reasonable). If it isn't, then whatever disclosure methods we use that are adequate for HUL systems are adequate for illegal systems of whatever unusuality. Either the people playing the illegal system do it right and potentially get caught, or don't do it and get nailed harder when it is found out (as the evidence is that they are actively concealing the understanding, which increases the chance that they are playing it knowing it is illegal and trying to get away with it).

[ggwhiz]

For heaven's sake: NO.

 

There can be no CPU from a properly disclosed agreement whether it is used or not used in a particular situation.

 

Would the lack of a pre-alert AND the provision of a suggested defense not confirm a CPU? The latter was only offered mid-auction after the bid was challenged.

[blackshoe]

Would the lack of a pre-alert AND the provision of a suggested defense not confirm a CPU? The latter was only offered mid-auction after the bid was challenged.

I would investigate whether they knew they were supposed to pre-alert and provide a defense, and if so why they did not. I would not take a failure to pre-alert or provide a defense as prima facie evidence of a CPU.

[Vampyr]

How is that specific to using an illegal system? Aren't there also negative inferences available from not using legal conventions? And unless your opponents know your system as well as you do, they may make assumptions that lead them to make incorrect inferences.

 

But the inferences that come with an illegal convention will never even occur to the opponents. I realise that this also, as above, applies to unusual methods as well. But the big difference is that one method is legal while the other is not.

[pran]

Would the lack of a pre-alert AND the provision of a suggested defense not confirm a CPU? The latter was only offered mid-auction after the bid was challenged.

Your own question implies that the agreement has not been properly disclosed so it can well be rephrased to:

 

Would an improperly disclosed agreement not confirm a CPU? And the answer to this question is of course: Sure it would.

 

May I (again) remind you that my statement was:

 

There can be no CPU from a properly disclosed agreement whether it is used or not used in a particular situation.

[akwoo]

But the inferences that come with an illegal convention will never even occur to the opponents. I realise that this also, as above, applies to unusual methods as well. But the big difference is that one method is legal while the other is not.

 

I think the intent in the drafting of the GCC is that any convention/system permitted by the GCC should be normal enough that all negative inferences resulting from it will occur to competent opponents (at least enough for the them to ask about it).

 

In other words, the GCC tries to make all methods that have negative inferences that won't occur to competent opponents illegal, so there is no distinction here.

[barmar]

In other words, the GCC tries to make all methods that have negative inferences that won't occur to competent opponents illegal, so there is no distinction here.

If that was the intent, I don't think it succeeds. I think many competent, but inexperienced, novices would not make the negative inferences that come from their opponents playing Precision, yet it's GCC-legal.

[mycroft]

I think that many competent, and highly experienced, not novices would not make the negative inferences that come from their opponents playing EHAA (even after the required pre-Alert), or Polish Club, or any of my area's homegrown "1♣ is 12-21 , yeah, that's about all we can say about it"; yet they're GCC-legal.

 

Assume I fix Fantunes to the Australian book so that I can handle the Marmic 12-14s (take them out of 1NT). I believe it's now GCC legal. Tell me people are going to trivially handle it.

 

I will cop to cheating a bit with that last. The players are competent enough to make up the system, but not competent enough to be able to explain it. But even after ferreting out what you can from the rest of their bids, it's still terra incognita.

 

I do think that *some* of this is a function of the One True Bidding Style that seems to be entrenched in ACBL club play; I have been asked (seriously) if we don't have to pre-Alert or Alert the fact that our 1m calls playing K/S are sound openers, and it's not like a 12-14 NT is all that weird.