[goffster]

http://tinyurl.com/p9u5o3p

Look, 2S is simply from outer space. Don't tell me about
any hand generator business, or any result. I certainly
could have been a little sharper on the defense here.

Surely there is a way for GIB to say, "I will only take
an egregious action when I feel I have not adequately described
my hand in a very fundamental way".

[1eyedjack]

And where is East's 7+ total points?

[Bbradley62]

1eyedjack, on 2015-November-02, 13:32, said:

And where is East's 7+ total points?

This is more of a description issue than a logic issue. East is trying to show that he has a maximum hand for having passed twice, and he does have that. If his partner is in the 21-22 total point range with four spades, game is possible.

[lycier]

This hand,just look like buggy bidding of weird basic robot in the past.

[iandayre]

Bbradley62, on 2015-November-03, 08:41, said:

This is more of a description issue than a logic issue. East is trying to show that he has a maximum hand for having passed twice, and he does have that. If his partner is in the 21-22 total point range with four spades, game is possible.

True but why not just raise to 3S?

[kuhchung]

hahahaha GIB

[Bbradley62]

iandayre, on 2015-November-03, 11:31, said:

True but why not just raise to 3S?

Good question. I wonder what the difference would be.

[goffster]

GIB says 2S shows 15-22 with 4 spades.
I *already* expect a good hand for the 2D bid.
So there is no reason at all to distort things
by bidding suits you don't have.

I think East's bid of 3H is actually good.
It has a spade and an ace more than it could have.

[Bbradley62]

goffster, on 2015-November-05, 15:55, said:

I think East's bid of 3H is actually good.
It has a spade and an ace more than it could have.

Then, how would you answer the previously-asked question: what would 3♠ have shown instead of 3♥?

[lorserker]

goffster, on 2015-November-02, 12:59, said:

http://tinyurl.com/p9u5o3p

Look, 2S is simply from outer space. Don't tell me about
any hand generator business, or any result. I certainly
could have been a little sharper on the defense here.

Surely there is a way for GIB to say, "I will only take
an egregious action when I feel I have not adequately described
my hand in a very fundamental way".

Hi, I completely agree that 2S is strange, very strange.
When something like this happens, it is almost always a bug. But when it isn't, the computer is usually right.

I ran a double dummy analysis on 1000 random deals with the following constraints:

South:
- must have a 12-15 balanced hand for his balancing 1NT)
- cannot have five spades
- must have at least three diamonds (because stopper)

North:
- must have at least 5 hearts
- can't have 9 or more points (would have overcalled 1H)
- can't have more than 5 points and 6+ hearts (would have overcalled 2H/3H)

East:
- can't have 6+ points
- can't have 5 points and 5 spades (would have responded 1S)
- can't have 3+ points and 6+ spades (would have responded 1S or competed 2S over north's 2H)
- can't have 3+ points and 3+ diamonds (would have competed 3D over north's 2H)
- can't have 7+ clubs (would have competed)

West:
- must have the had as in the diagram SAQ6 HAJ3 DKJ6543 CT

The results are that 2S is a winning bid about 60% of the time (at matchpoints). This is mainly because north's 2H often makes, and east will have four spades about half the time and five spades a quarter of the time (meaning we have at least a 7 card fit 75% of the time). Even if east has less than three spades he can pull to 3D if he has a fit.

Some example hands where bidding 2S will work (N E S W):
ST984 HT9765 D9 CAQ8 SJ732 H84 D87 CK9652 SK5 HKQ2 DAQT2 CJ743 SAQ6 HAJ3 DKJ6543 CT (2S is one down, but 2H makes)
S85 HK9652 DQ2 CK987 SJT42 HT4 D98 CJ5432 SK973 HQ87 DAT7 CAQ6 SAQ6 HAJ3 DKJ6543 CT
S843 HKQT72 D2 CJ542 SK952 H5 DT9 CQ98763 SJT7 H9864 DAQ87 CAK SAQ6 HAJ3 DKJ6543 CT (2S will make)
ST53 HQ8752 DAQ C542 SJ9842 H64 DT8 CQ763 SK7 HKT9 D972 CAKJ98 SAQ6 HAJ3 DKJ6543 CT
SJT9 HQ8652 DA97 C86 S8743 HKT7 D8 CJ9732 SK52 H94 DQT2 CAKQ54 SAQ6 HAJ3 DKJ6543 CT

Some hands where bidding 2S will backfire:
S72 HQ9876 DQ9 CKJ94 SJ953 H42 D87 CQ6532 SKT84 HKT5 DAT2 CA87 SAQ6 HAJ3 DKJ6543 CT (going down too much)
SK854 HQ8742 D2 CQJ6 S972 HT65 DQ CK97542 SJT3 HK9 DAT987 CA83 SAQ6 HAJ3 DKJ6543 CT
S987 HT9652 DA CA984 S432 HQ87 DT2 CK7652 SKJT5 HK4 DQ987 CQJ3 SAQ6 HAJ3 DKJ6543 CT (going down when 2H was also going down)
SJ8 HQT972 D98 CQ753 ST732 H654 DT2 CAJ96 SK954 HK8 DAQ7 CK842 SAQ6 HAJ3 DKJ6543 CT
S85 HKQ654 DQT2 C987 ST974 HT92 D8 CK6542 SKJ32 H87 DA97 CAQJ3 SAQ6 HAJ3 DKJ6543 CT

Even at imps 2S seems to be +EV, but I'm not so confident in this because doubles will make things ugly (if opps never double 2S will win, if opps always double 2S will win, even if opps double with 100% accuracy, which is practically impossible, 2S loses less than 2 imps per board)

In conclusion, the bid of 2S is not so bad, although it is very strange and might be just a bug in the end

[1eyedjack]

lorserker, on 2015-November-15, 19:08, said:

In conclusion, the bid of 2S is not so bad

And your opinion of 3S is?

[lorserker]

@1eyedjack i feel this is a trap question

maybe i misinterpret, but:

1. if you are just making fun because you think that 2S is ridiculous and are curious what i can come up with to defend a bid of 3S instead of 2S, my answer is: LOL

2. if you want my opinion about the actual outcome, because "if 2S is so good, why are they failing in 3S now"
The contract of 3S is too high, it will fail more often and get doubled more often, it is a bad outcome.
East has some reason for inviting because he is really maximum for what he has shown so far, and opposite a real hand of 4-2-6-1 game is a possibility. Nevertheless many human easts will pass that hand because either it will not occur to them that they are maximum, or they will recognize that they are ahead of the field just by being in a spade contract and it is ok to pass.
It is also a weakness in my analysis, and I should update my model saying that if east has an ace and a fit the contract will actually be 3S, not 2S

[1eyedjack]

Nothing Machiavellian in my question. I can understand that simulations might make 2S a reasonable action. I was just curious whether the same argument might be used to defend the 3S follow-up, because my personal opinion is that that bid is out there with the fairies.

[lorserker]

1eyedjack, on 2015-November-16, 03:40, said:

Nothing Machiavellian in my question. I can understand that simulations might make 2S a reasonable action. I was just curious whether the same argument might be used to defend the 3S follow-up, because my personal opinion is that that bid is out there with the fairies.

i updated the simulation making east invite whenever he has 4+ spades and an ace, and the possibility of playing 3S makes the whole thing less attractive. 2S seems to be break-even now, but i'm sure it's actually worse due to more frequent doubling on the 3 level.

anyway, i'm not sure what the conclusion is, it's either 2S is very close and not worth bidding, or 2S is a good but east must never raise it.

[Bbradley62]

lorserker, on 2015-November-16, 14:59, said:

... or 2S is a good but east must never raise it.

This is a concept we've discussed a lot... There are bids that humans make (and recognize) as purely competitive -- if it pushes opponents up one level it has done it's job... GIB may sometimes decide that it should make such a bid... but GIB will never consider the possibility that his partner has just made such a bid.