[emalka]

---

All Souths who opened 1C got to 6S and the rest who opened 2C or 2NT got to 6C

[barmar]

I think you'd probably have the same problem playing with a human partner.

How do you think the auction should go after a 2♣ opening to get to 6♠?

This is why strong club systems were invented, they allow more room to describe your hand.

[Bbradley62]

barmar, on 2011-November-07, 20:22, said:

This is why strong club systems were invented, they allow more room to describe your hand.

Since GIB doesn't play a strong club system, that comment is not at all helpful.

[Bbradley62]

barmar, on 2011-November-07, 20:22, said:

How do you think the auction should go after a 2♣ opening to get to 6♠?

This is clearly not what she wants. She wants to get to the good 6♣ contract after opening 1♣, not the bad 6♠ contract.

[barmar]

Bbradley62, on 2011-November-07, 20:46, said:

Since GIB doesn't play a strong club system, that comment is not at all helpful.

I was pointing out that this is a known problem with 2/1, and the solution humans came up with was to play a totally different system, not to tweak 2/1.

GIB's system does allow it to bid a 4-card major after 2♣-2♦-3♣, but the rule for showing good support for opener's suit takes precedence. Do you think we should switch that around? If North bid 3♠, and South doesn't have spade support, will that make it harder to find the club slam?

[Bbradley62]

What would it show if North bid 3♣ over 2♦? South would then pattern out, but North should know to place the contract in the 10-card fit instead of the 7-card fit. Not sure of the specifics, but North shouldn't hide the fit.

[cloa513]

Can't North bid 2♥ as game force and then over 2♠ bid 3 ♣ or 4 ♣ to set trumps?

[emalka]

barmar, on 2011-November-07, 21:19, said:

I was pointing out that this is a known problem with 2/1, and the solution humans came up with was to play a totally different system, not to tweak 2/1.

GIB's system does allow it to bid a 4-card major after 2♣-2♦-3♣, but the rule for showing good support for opener's suit takes precedence. Do you think we should switch that around? If North bid 3♠, and South doesn't have spade support, will that make it harder to find the club slam?

I am talking about finding 6♣ after 1♣ opening.
The problem here is that after 1♣-1♠-2♦ GIB rebids 2♠ which promises 5+ spades as it is said in the explanation.
GIB should support clubs after 2♦.

[georgi]

emalka, on 2011-November-07, 23:19, said:

I am talking about finding 6♣ after 1♣ opening.
The problem here is that after 1♣-1♠-2♦ GIB rebids 2♠ which promises 5+ spades as it is said in the explanation.
GIB should support clubs after 2♦.

Let say we have three situations. Assuming 2♦ is matching its strength and you should attitude toward that.
GIB has minimum hand.
GIB has invitational hand.
GIB has hand to make forcing to game.

It doesn't seem so certain 3♣ is a strong hand. What should GIB do with weakish hand and 4+♠ and 3/4♣?

Something like : ♠AJxx ♥xxx ♦xxx ♣Qxx

1♣ - 1♠
2♦ - Opener reverse -- 5+ C; 4+ D; 3- S; 21- HCP; 18-22 total points - And now?

sometimes you don't have the perfect hand to fit in your call. That's not always wrong to deviate around a bit.

You can't bid 2NT as stronger hand and as you have nothing in ♥, and you don't have 5+♠ to promise, no 3♦ option either.

When you are in forcing, but not to game, you should have option to stop safely.
So in this auction, where 2♦ is not still GF ( but you have to make appropriate attitude toward), 3♣ looks like negative choice, then to support and forcing up.
With the particular hand above ( we have 11HCP and super fit at least in one of the minors ), 3♣/2NT doesn't look right, more likely initially 2♥(which call may need a tweak) then fit in ♣.

[barmar]

lol, I didn't even notice that North rebid his 4-card suit in the OP.

GIB's system over reverses is not very sophisticated. It doesn't play 4th Suit Forcing or any Lebensohl-like convention, so it can't distinguish good and bad raises of opener's suit. 3♣ shows a minimum preference, and the North hand is too strong for this. 4♣ is a possible bid (it shows 7+ total points), but we try to avoid bypassing 3NT to bid a minor.

Since it has enough points for game, but no other acceptable bid, the book bid is 3NT, despite not having a heart stopper. But simulations convince it otherwise, so it tries 2♠, presumably because this is forcing; opener can bid NT if he has a heart stopper.

[chasetb]

barmar, on 2011-November-07, 23:41, said:

lol, I didn't even notice that North rebid his 4-card suit in the OP.

GIB's system over reverses is not very sophisticated. It doesn't play 4th Suit Forcing or any Lebensohl-like convention, so it can't distinguish good and bad raises of opener's suit. 3♣ shows a minimum preference, and the North hand is too strong for this. 4♣ is a possible bid (it shows 7+ total points), but we try to avoid bypassing 3NT to bid a minor.

Since it has enough points for game, but no other acceptable bid, the book bid is 3NT, despite not having a heart stopper. But simulations convince it otherwise, so it tries 2♠, presumably because this is forcing; opener can bid NT if he has a heart stopper.

That's not the only think you didn't notice. Regardless of playing lebensohl or Ingberman or just 'natural' over reverses, North has a clear bid in my book - 4♥! GIB has 11 prime points, 5 controls (6 counting the singleton), and 5-card support when partner has shown at least 16/17, and 5♣-4♦. So let's show the support via a splinter.

If GIB presumes that 4♥ is natural, then that explains a lot. I will say though that I agree on the Precision comment you made earlier, though that really has no bearing on the bidding sequence.

[barmar]

Yes, 4♥ would be natural. For some reason, there's a single rule that covers 2-4♥. The 3 level make sense, since it has to include 1♦ 1♠ 2♥ 3♣; I guess the 4 level was thrown in because there was no other meaning for the bid.

If 4♥ were a splinter, wouldn't it be in support of diamonds, since that's the last bid suit?

[Bbradley62]

Bbradley62, on 2011-November-07, 21:33, said:

What would it show if North bid 3♣ over 2♦?

georgi, on 2011-November-07, 23:40, said:

It doesn't seem so certain 3♣ is a strong hand.

I guess I didn't ask the question correctly. If the auction goes 1♣-1♠-2♦-3♣, what description would GIB provide for the 3♣ bid?

[georgi]

Bbradley62, on 2011-November-08, 08:05, said:

I guess I didn't ask the question correctly. If the auction goes 1♣-1♠-2♦-3♣, what description would GIB provide for the 3♣ bid?

1♣ - 1♥/♠
2♦ - 3♣ - Raise -- 3+ ♣; 4+ ♥/♠; 6-9 total points

[Bbradley62]

cloa513, on 2011-November-07, 23:05, said:

Can't North bid 2♥ as game force and then over 2♠ bid 3 ♣ or 4 ♣ to set trumps?

Hopefully this will be the final answer

[barmar]

Bbradley62, on 2011-November-08, 09:45, said:

Hopefully this will be the final answer

Only if the answer you're looking for is that we should change GIB's sytem to play FSF in this sequence.

I play it with my human partners, so I certainly think it's reasonable. We just have to be careful whenever we think about changing the system, for the sake of users who aren't familiar with all the gadgets. I think GIB's system is deliberately kept relatively simple to avoid confusing novices and intermediates -- that's why you don't see conventions that many advanced players play, like Drury and Puppet Stayman. It's a compromise between effectiveness and complexity (just as when making agreements with human partners).

[xxhong]

For now, I think a good fix is to set 1C 1S 2D 4C as a good hand with C support which has some slam interest.
Also, 4D shows a good hand with D support. a typical range should be 11+, not some random 7+ total points. This is a very simple fix.

Also, now the 1C 1S 2D 3C isn't very playable. 3C as I remember shows 6+. IMO, it should show 6-7 and is passable. With better hands, you either bid 4C to show slam interest, bid 5C to play there, bid 3NT when you think you have a reasonable chance to make it, or bid the 4th suit when you don't have a stopper.

Also, 2H to be natural doesn't make much sense here because opener has denied 4 hearts. It can be useful only with 5-5 majors, still, that's rare and you can always bid 2H then later 3H to show that shape.

There are indeed many such kind of bad designs in the system. A simple system doesn't mean it has to be bad. Just like the well known case of 1H 1S 3H, it really can't show 16+. It should be something like 16-18, with 19+, a simple system would just bid 4H or 3NT, depending on the H length and quality.

barmar, on 2011-November-08, 11:39, said:

Only if the answer you're looking for is that we should change GIB's sytem to play FSF in this sequence.

I play it with my human partners, so I certainly think it's reasonable. We just have to be careful whenever we think about changing the system, for the sake of users who aren't familiar with all the gadgets. I think GIB's system is deliberately kept relatively simple to avoid confusing novices and intermediates -- that's why you don't see conventions that many advanced players play, like Drury and Puppet Stayman. It's a compromise between effectiveness and complexity (just as when making agreements with human partners).

[barmar]

FYI, this thread has prompted us to teach GIB the modern way to bid after a reverse. We'll be adding Lebensohl, FSF, jump raises as slam tries, etc.

It's too soon to provide to a release time for this, it's a significant amount of work.

[Bbradley62]

barmar, on 2011-November-09, 02:15, said:

FYI, this thread has prompted us to teach GIB the modern way to bid after a reverse. We'll be adding Lebensohl, FSF, jump raises as slam tries, etc.

It's too soon to provide to a release time for this, it's a significant amount of work.

Excellent! Thanks!