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Why won't GIB prefer my first bid suit?

#1 User is offline   Jyrki_63 

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Posted 2023-February-05, 02:33

This I have never understood.

I realize that with a weak hand the opener may need to open, say a 4 card diamond ahead of a 5 carder in clubs, if they plan to show both suits. But with a strong hand??

Zenith hand from yesterday

I open 1D, the opps interfere with 1S. First GIB asks me to show a second with a TOX. The RHO pre-empts with a 3S. I have extras with 0364 shape, so I show my clubs. With 33 in the minors GIB then later decides that clubs make a better trump suit?

I do know to look at the bid descriptions. It says that my 4C promises rebiddable clubs. But that is just ridiculous. Say GIB is 55 or 54 or 44 in the rounded suits. We are never going to find the club fit unless I bid them. Furthermore, as I am willing to commit to the four level, I promise extra strength. Therefore we are not in a situation where I might want to open in a shorter suit.

Several years ago GIB insisted on playing in a 52 heart fit instead of 65 available in clubs. I had a strong hand with 6 clubs and 5 hearts (judging from the bidding I could have only had four hearts).

Exactly what rules is GIB following when making a preference? It is as if it never believes my minor openings were real suits.
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#2 User is offline   pilowsky 

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Posted 2023-February-05, 03:41


Isn't that a Negative double, not a Takeout double?
From Bridgebum:

Rebids by Opener
With 4+ cards in partner's shown suit, opener can bid it at the cheapest level with a minimum hand. Lacking 4 cards, opener can do one of the following:

Rebid a 5-card (preferably at least 6-card) suit.
Bid notrumps with a stopper in the enemy suit.
Bid a new suit naturally (a reverse still shows a strong hand).
Cue-bid the enemy suit with a strong balanced hand that lacks a stopper in that suit.
Bid partner's shown suit with only 3 cards (last resort).


Non legit hoc
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#3 User is offline   thepossum 

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Posted 2023-February-05, 03:52

I have endless problems with minors and GiB
Don't know if it is GiB's fault or 5-card majors
It will just ignore a great minor contract sometimes
Not apropos necessarily of that hand

But seriously saying twice rebiddable is problematic - I think I would have rebid diamonds but I wasn't there :)
Are you supposed to bid clubs first then diamonds. Who would know
I put it through one of my reference computer 2/1 systems and instead of 4C south doubled and ended up in 4Sx by West
The system is a mystery to me

I may well have passed or bud 4D. Who knows what happens
Ignore what I said. My reference system after 4D went for a 5C cue bid and ended in 5D :lol:

But after all these years I am still trying to lern the systems and attempt to look at the bid descriptions, no matter how crazy they may seem

After further experimentation the problem could be the system Unless your fist bid is 2NT (unusual) or MSS do not give it a choice of minors

As you can see I am endlessly fascinated and terminally confused by this bidding system
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#4 User is offline   mcphee 

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Posted 2023-February-05, 05:18

Robots are not able to make a rational bid based on logic. The do so many crazy things trust is not an option. I have offered them free lessons but they declined, proof positive they must have huge egos. They even try to get a ruff in NT. They are able to add and subtract. And 100% when your side has 36 total points you are playing 7NT without even think about blackwood. The advanced robots are also sharp as a marble.
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#5 User is offline   smerriman 

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Posted 2023-February-05, 13:56

View PostJyrki_63, on 2023-February-05, 02:33, said:

I open 1D, the opps interfere with 1S. First GIB asks me to show a second with a TOX.

For reference, this is a negative double, not a takeout double, which just shows exactly 4 hearts (or possibly 5+ hearts with a hand too weak to bid 2). It doesn't say anything about clubs, so it's not accurate to say that it's asking you to "show a second".

View PostJyrki_63, on 2023-February-05, 02:33, said:

We are never going to find the club fit unless I bid them.

This isn't entirely accurate either, since you do have the option of doubling to show extras while denying heart support, after which you'll be pretty well placed with any of GIB's responses.

But aside from those points, you're obviously right that the description of 4 is very silly. While I can replicate it at a bidding table, I can't actually replicate this with the older version of GIB that I have; back then it defined 4 as 4+ C; 4+ D; 3- H; 21- HCP; 18-22 total points, and is what GIB picks too. So this must have gotten messed up by one of the changes BBO made since then.

However, I suspect the logic is similar to that I posted about in this thread, where GIB has some generic rules about how long a new suit must be if first bid at a certain level, and the fact that diamonds must initially be described as a 3 card suit means its increment function breaks.
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#6 User is offline   Jyrki_63 

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Posted 2023-February-06, 00:58

View Postsmerriman, on 2023-February-05, 13:56, said:

For reference, this is a negative double, not a takeout double, which just shows exactly 4 hearts (or possibly 5+ hearts with a hand too weak to bid 2). It doesn't say anything about clubs, so it's not accurate to say that it's asking you to "show a second".


This isn't entirely accurate either, since you do have the option of doubling to show extras while denying heart support, after which you'll be pretty well placed with any of GIB's responses.


Thanks for the bit about the meaning of the first double. At some level I was aware of that. After all, the expectation of getting covers for my heart losers played a big role in my hand evaluation. Anyway, that doesn't change the fact that 4C is, in my opinion, the logical rebid.

The suggestion that I should Double as my rebid sounds dangerous. Even if not strictly for penalties won't that show tolerance for defending 3SX and no interest in a heart contract? Typically 3252 or 4243 shape with extra strength, may be 2353? If that same bid used also for 0364, the range of hands is too much to sort out with subsequent bidding. We are at the four level next already. And we may well belong in hearts (this is MPs). Even if partner doesn't have five, it looks like this hand may play well in a Moysian.

If I bid 4D, GIB may well pass even if we want to play in a rounded suit. That could still be right, of course.

I do appreciate the difficulties of defining a bidding system with rules a computer could follow. Reading the older thread (thanks for the link!), the way I see it the problem is that due to the 5-card major system we cannot have a blanket rule that the first bid suit is the longest. But this does not apply if A) both bid suits are minors, or B) the subsequent bidding implies that the major suit has 5 cards or more (when the systemic opening on a 3 or 4 card minor is out of the question). In other words, this seems to be something that could be fixed simply by "just adding an if...then -clause" or two.

Of course, the system definitions should primarily be geared to dealing with the more common hand types as opposed to these wilder hands.

---

Mind you, I'm sure this and many other problems with GIB's bidding have been discussed earlier. Yet, the search didn't show anything. Apparently I also miss something about how to best use this resource.
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#7 User is offline   smerriman 

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Posted 2023-February-06, 01:05

Yeah, wasn't necessarily saying that you *should* double, just that is it was another potential option to find clubs, especially if 4 is stuck as showing 6.

But as to your later point, unfortunately that type of "if then else" isn't remotely possible with the GIB database format. It's pretty insane, which is probably one of the reasons the developers have given up on it. But definitely some fixable parts, if only they'd let someone try :(
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#8 User is offline   helene_t 

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Posted 2023-February-06, 03:01

Yes, GIB doesn't have a general understanding of preference bids. It may have provisions for preference bids in some specific situations, though.

So the answer to your questions is that it's a bug.
The world would be such a happy place, if only everyone played Acol :) --- TramTicket
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