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The Good, The Bad and The Ugly Robot Rulings

#1 User is offline   lamford 

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Posted 2020-June-09, 03:09



a) You have a normal enough auction 1NT-3NT, and West leads the queen of spades and East will follow with the four. Sadly, the move is called and you, as TD, have to find the best line, and adjudicate the result of the board. What is the best line and its approximate chance of success?

b) Two conservative bidders have the auction 1NT(10-12)-All Pass, against two robots, and again West leads the queen of spades. East would follow with the four, but declarer claims seven tricks (against two robots) at trick one. The robots will accept the claim if there is a 100% line for the contract. Is there?

c) Two aggressive bidders have the auction 1NT(15-17)-(Pass)-7NT-(All Pass) and again West leads the queen of spades. East would follow with the four but again the move is called. GIB adjudicates the result of the hand as 7NT=, so there is no defence. What is the exact layout of the East-West hands?
No, I meant exactly what I wrote; I believe BBO's claiming algorithm is about as perfect as it can get. It's basically the only aspect of GIB that I find faultless. - smerriman
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#2 User is offline   Cyberyeti 

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Posted 2020-June-09, 04:31

c) I think W needs QJ10, 9xxxx, KQ, K9x you can pick the clubs up for no loser and then triple squeeze him.
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#3 User is offline   lamford 

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Posted 2020-June-09, 05:02

View PostCyberyeti, on 2020-June-09, 04:31, said:

c) I think W needs QJ10, 98765, KQ, K97 you can pick the clubs up for no loser and then triple squeeze him.

progressively squeeze him I think is the correct jargon ... but well done. That is the easier one of the three I think!
No, I meant exactly what I wrote; I believe BBO's claiming algorithm is about as perfect as it can get. It's basically the only aspect of GIB that I find faultless. - smerriman
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#4 User is offline   Cyberyeti 

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Posted 2020-June-09, 06:53

b) is that if there is a 100% line in abstract ? or it's impossible to screw up however badly you play it given what the robot is looking at ? for example the clubs have several potential losers, but if they're actually W: Jx E:Kx it's very difficult to lose more than one by any vaguely sensible play. I think that said there is a line that guarantees 7 tricks. Does the concession take the bidding into account to outlaw some possibilities (like W holding 7 spades and a couple of potential entries but staying silent) ?

a) It's as good as all the 2-2 club breaks and 3/4 of the 3-1 breaks for the simple line of ace and small to the Q, you lose to KJx over the Q and both 4-0s.
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#5 User is offline   lamford 

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Posted 2020-June-09, 11:14

View PostCyberyeti, on 2020-June-09, 06:53, said:

b) is that if there is a 100% line in abstract ? or it's impossible to screw up however badly you play it given what the robot is looking at ? for example the clubs have several potential losers, but if they're actually W: Jx E:Kx it's very difficult to lose more than one by any vaguely sensible play. I think that said there is a line that guarantees 7 tricks. Does the concession take the bidding into account to outlaw some possibilities (like W holding 7 spades and a couple of potential entries but staying silent) ?

a) It's as good as all the 2-2 club breaks and 3/4 of the 3-1 breaks for the simple line of ace and small to the Q, you lose to KJx over the Q and both 4-0s.


In b) there is, I believe, only one 100% line, which succeeds on any distribution. The robot wrongly rejects the claim of 1NT=.

In a) there are four reasonable lines, a) a club to the ace and then a club to the queen, b) a club to the ten, c) a club to the queen, and d) a club to the eight. Which will you go for?
No, I meant exactly what I wrote; I believe BBO's claiming algorithm is about as perfect as it can get. It's basically the only aspect of GIB that I find faultless. - smerriman
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#6 User is offline   Cyberyeti 

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Posted 2020-June-09, 12:04

View Postlamford, on 2020-June-09, 11:14, said:

In b) there is, I believe, only one 100% line, which succeeds on any distribution. The robot wrongly rejects the claim of 1NT=.

In a) there are four reasonable lines, a) a club to the ace and then a club to the queen, b) a club to the ten, c) a club to the queen, and d) a club to the eight. Which will you go for?


a) depends what you're going to do on the second round also. Nothing works for void with W.

Club to the ace and club back loses to small singleton and void with E

CLub to the 10 A loses to stiff J or void with E and small singleton with W so is worse

club to the 8 loses to stiff 9 with E or small stiff with W, but also you have to decide what to do when the 8 loses to the J.

club to the Q loses to void with E and stiff K with W straight off, but if the Q loses to the K, you need to decide whether to finesse or play for the drop. If you finesse you lose to the 2 Jxs with E, if you play for the drop you lose to both small stiffs with E.

It appears club to the A is clearly best.

b) club to the 10 may not be theoretically 100% but practically is given the lead.
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#7 User is offline   lamford 

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Posted 2020-June-11, 12:11

for a) you are right. The two best lines are ace and low to the queen, around 78% and a low club to the queen, a little under 77%. The gap is a bit wider maybe, as the fact that West has an honour sequence in spades, increases his chance of a singleton king of clubs a little.

For b) that is one of the failing lines which goes off when West has misclicked on the stiff queen of spades, and East has KJ9 of clubs. If you try to endplay West in the red suits, East turns up with the ♦KQ. If you cas. the ♥A and ♥K first, west has ♥QJ98xx and you lose seven tricks. I was looking for a 100% line, not a 99.9% one!
No, I meant exactly what I wrote; I believe BBO's claiming algorithm is about as perfect as it can get. It's basically the only aspect of GIB that I find faultless. - smerriman
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#8 User is offline   Cyberyeti 

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Posted 2020-June-11, 12:33

View Postlamford, on 2020-June-11, 12:11, said:

for a) you are right. The two best lines are ace and low to the queen, around 78% and a low club to the queen, a little under 77%. The gap is a bit wider maybe, as the fact that West has an honour sequence in spades, increases his chance of a singleton king of clubs a little.

For b) that is one of the failing lines which goes off when West has misclicked on the stiff queen of spades, and East has KJ9 of clubs. If you try to endplay West in the red suits, East turns up with the ♦KQ. If you cas. the ♥A and ♥K first, west has ♥QJ98xx and you lose seven tricks. I was looking for a 100% line, not a 99.9% one!


If you're going to allow for misclicks ... Playing real bridge this is good enough, I had actually foreseen the stiff Q situation and assumed this being online he'd have asked for an undo.
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#9 User is offline   lamford 

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Posted 2020-June-29, 10:42

View PostCyberyeti, on 2020-June-11, 12:33, said:

If you're going to allow for misclicks ... Playing real bridge this is good enough, I had actually foreseen the stiff Q situation and assumed this being online he'd have asked for an undo.

There are no undos in the play in EBU events. Our club has an interesting rule that a defender can get an undo, but not if he misclicks on an honour as here, so a similar rule to an MPC in live bridge. So, you need the 100% play of rising and playing a low club.
No, I meant exactly what I wrote; I believe BBO's claiming algorithm is about as perfect as it can get. It's basically the only aspect of GIB that I find faultless. - smerriman
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