How to avoid bidding Grand Slam off 3 keycards

[riverwalk3]

In this deal, my robot opponents bid to a slam off 3 keycards: https://tinyurl.com/25f95txj I knew from the 5NT followup and my own hand that they were probably missing 3 keycards (and thus my partner held an ace), so I doubled them even though they stopped in 6. All 3 keycards took a trick, so they went down 2.

 

Note that East could still have 5 keycards from the bidding (all 5 keycards is 19 HCP, + singleton makes 21 total points, which is stil slightly too weak for opening 2 clubs. [hv=pc=n&s=sj974hk97da9cjt92&w=s62hqj8532d2ckq43&n=sat85hdjt865c8765&e=skq3hat64dkq743ca&d=w&v=n&b=12&a=pp1dp1hp4cp4np5hp5np6dp6hppdppp&p=c5cac2c4d4dad2d5s4s2sas3d6d3d9h5h3c6hthks7s6s5skh6h7h8s8h2c8hah9d7c9hjdjc3c7h4ctsqs9hqstckd8dqcjcqdtdk]399|300[/hv]. However, once East shows the diamond king, West signs off in 6 hearts because it's impossible for East to have all 5 keycards then (that would mean 22 HCP + singleton, which would probably open 2 clubs). If West still thought East had 5 keycards, this would warrant a 7 hearts bid (6 hearts, 3 clubs, 1 spade, 2 diamonds, 1 club ruff).

[Gilithin]

It looks like there was a system misunderstanding regarding splinters. These AIs get more human every year...

[Cyberyeti]

This auction is strange.

 

W fails to open 2♥

E splinters a singleton A which many don't recommend

W Blackwoods with no key cards

 

E is trying to hit a very narrow target Axx, KQxxx, xx, xxx or similar that is not a 1 or 2 opener and has ♥KQ and an ace

[smerriman]

This should go in the GIB forum, not this one.

 

It looks like there was a system misunderstanding regarding splinters. These AIs get more human every year...

*Every* GIB auction involving a splinter results in a misunderstanding. GIB will happily splinter itself, but as a human it's highly dangerous splintering opposite it as it has no clue how to respond.. the most common response you see is a cuebid of the splinter suit holding KQxx, so I'm actually somewhat surprised that didn't happen here :) As for GIB opposite GIB, well, I guess it just rarely comes up with most tournaments best-hand.

 

It's really quite bizarre the robot wasn't programmed to handle them better, since responses to splinters are really quite algorithmic.

 

E is trying to hit a very narrow target Axx, KQxxx, xx, xxx or similar that is not a 1 or 2 opener and has ♥KQ and an ace

East isn't even trying to hit anything, there's zero planning; it's just told to splinter with any hand with 19+ total points, 4+ support and 0-1 clubs. After that 4NT is just total points based (+3 for the short suits), and West is not even calculating that East may or may not have enough points to hold aces, it just assumes missing 3 KC is impossible in general and is forced to bid 5NT.

[bluenikki]

There are many silly things about the auction. But the real structural problem is that the 2-or-5 response fell on the trump suit.

 

Suppose the suit had been spades. West would sign off in 5♠. If east had 5 they would continue.

[pescetom]

I still don't see why it bids 5NT if it intends to stop in 6H after 6D offering a home for a black suit loser if necessary.

The only situation in which 5NT makes sense as I see it is if one intends to bid the grand with either or both pointy kings (or is determined with diamonds and prepared to risk with spades).

[helene_t]

I still don't see why it bids 5NT if it intends to stop in 6H after 6D offering a home for a black suit loser if necessary.

It seems to bid 5NT all the time it has all the keycards, but since it can't locate a king about the trump suit, it will just sign off no matter what the answer is, unless it has all kings above the trump suit itself.

 

Anyway, I suspect it doesn't really use the splinter information when deciding whether to try for slam after a splinter. Usually it will just sign off when it doesn't have significant extras, even with something perfect like Axx or xxx in the splinter suit. Here, it seems not to be aware that ♣KQ don't carry much weight opposite a splinter (and the extra trump length also not much since there's probably no need to ruff clubs). It would be better for the robot to play 4♣ as Swiss-by-opener instead of using it as a splinter.

[smerriman]

It seems to bid 5NT all the time it has all the keycards

Correct - there's no grand slam try component to it; it's just forced to bid it.

[johnu]

This auction is strange.

 

Looks like standard GIB to me.

[Cyberyeti]

Looks like standard GIB to me.

 

What is GIB's requirement for a weak 2 ?

[fromageGB]

There are many silly things about the auction. But the real structural problem is that the 2-or-5 response fell on the trump suit.

No. The real structural problem is playing a modulus 3 ace asking, eg 0 or 4, 1 or 5. In many hands that is not a narrow enough target to be sure.

[bluenikki]

No. The real structural problem is playing a modulus 3 ace asking, eg 0 or 4, 1 or 5. In many hands that is not a narrow enough target to be sure.

It doesn't matter what the mod is. Blackwooder assumes the lower value, no matter how unlikely that seems. Blackwoodee must continue over the sign-off when holding the higher value. To protect against committees, that should be on the convention card. "Forcing to slam facing 3+ keycards."

 

The problem comes when the reply coincides with the trump suit, because the above rule would make Blackwooder pass if 2 keycards may be missing.

[Gilithin]

It doesn't matter what the mod is. Blackwooder assumes the lower value, no matter how unlikely that seems. Blackwoodee must continue over the sign-off when holding the higher value. To protect against committees, that should be on the convention card. "Forcing to slam facing 3+ keycards."

 

The problem comes when the reply coincides with the trump suit, because the above rule would make Blackwooder pass if 2 keycards may be missing.

In most auctions that works but if, for example, we open 2 and Responder ends up doing the asking, I am not convinced it is good bridge to continue after the sign-off on 3 key cards. But naturally YMMV.

[bluenikki]

In most auctions that works but if, for example, we open 2 and Responder ends up doing the asking, I am not convinced it is good bridge to continue after the sign-off on 3 key cards. But naturally YMMV.

As far as I am concerned, a weak 2 cannot have 3 keycards. And certainly a responder to that weak 2 cannot ask when they have only 1 keycard themself.

[Gilithin]

As far as I am concerned, a weak 2 cannot have 3 keycards. And certainly a responder to that weak 2 cannot ask when they have only 1 keycard themself.

That should have been 2♣ not a Weak 2. I would hope your 2♣ openers can have 3 key cards.