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Robot gives away free overtricks at matchpoints when it realizes it cannot defeat the contract skip all the way to the tenth trick

#1 User is offline   goffster 

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Posted 2016-January-09, 15:16

when the spade jack is lead at trick 10, it is 100% obvious
to take the queen and lead the club ten.

There can be no second choice whatsoever.

The robot however ducks! Giving up a trick.

This makes me believe that GIB enters a "Dont care" zone
when it realizes the contract cannot be beat, even at matchpoints.

http://tinyurl.com/zcv27gf
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#2 User is offline   1eyedjack 

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Posted 2016-January-09, 15:25

Ummm - no hand
Psych (pron. saik): A gross and deliberate misstatement of honour strength and/or suit length. Expressly permitted under Law 73E but forbidden contrary to that law by Acol club tourneys.

Psyche (pron. sahy-kee): The human soul, spirit or mind (derived, personification thereof, beloved of Eros, Greek myth).
Masterminding (pron. mPosted ImagesPosted ImagetPosted Imager-mPosted ImagendPosted Imageing) tr. v. - Any bid made by bridge player with which partner disagrees.

"Gentlemen, when the barrage lifts." 9th battalion, King's own Yorkshire light infantry,
2000 years earlier: "morituri te salutant"

"I will be with you, whatever". Blair to Bush, precursor to invasion of Iraq
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#3 User is offline   goffster 

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Posted 2016-January-09, 17:19

sorry, linked added to hand
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#4 User is offline   Bbradley62 

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Posted 2016-January-09, 19:47

It appears that West simulates holdings, and all of his simulations say that North's last non-spade is J, in which case his play actually doesn't matter. Ick!
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#5 User is offline   1eyedjack 

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Posted 2016-January-09, 22:26

It doesn't matter what north's last nonspade is. West wins q and leads club. If north discards then west wins trick 12. If north ruffs then west wins trick 13. OP is correct. There is no simulation where west ducking does not concede a trick
Psych (pron. saik): A gross and deliberate misstatement of honour strength and/or suit length. Expressly permitted under Law 73E but forbidden contrary to that law by Acol club tourneys.

Psyche (pron. sahy-kee): The human soul, spirit or mind (derived, personification thereof, beloved of Eros, Greek myth).
Masterminding (pron. mPosted ImagesPosted ImagetPosted Imager-mPosted ImagendPosted Imageing) tr. v. - Any bid made by bridge player with which partner disagrees.

"Gentlemen, when the barrage lifts." 9th battalion, King's own Yorkshire light infantry,
2000 years earlier: "morituri te salutant"

"I will be with you, whatever". Blair to Bush, precursor to invasion of Iraq
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#6 User is offline   Bbradley62 

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Posted 2016-January-09, 23:51

View Post1eyedjack, on 2016-January-09, 22:26, said:

It doesn't matter what north's last nonspade is. West wins q and leads club. If north discards then west wins trick 12. If north ruffs then west wins trick 13. OP is correct. There is no simulation where west ducking does not concede a trick

Yes, any (reasonable) human would have played as you say. But we all (should) know that this is not how GIB approaches the problem. GIB runs simulations to determine likelihoods of various holdings, and if his sample size is too small, weird things can happen.

But, I wonder whether the 2 bid should preclude the possibility that North has exactly 5 spades and 4 hearts.
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#7 User is offline   1eyedjack 

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Posted 2016-January-10, 03:13

You are right. Blind spot my side. Had visions of Heart Jack being high.
Psych (pron. saik): A gross and deliberate misstatement of honour strength and/or suit length. Expressly permitted under Law 73E but forbidden contrary to that law by Acol club tourneys.

Psyche (pron. sahy-kee): The human soul, spirit or mind (derived, personification thereof, beloved of Eros, Greek myth).
Masterminding (pron. mPosted ImagesPosted ImagetPosted Imager-mPosted ImagendPosted Imageing) tr. v. - Any bid made by bridge player with which partner disagrees.

"Gentlemen, when the barrage lifts." 9th battalion, King's own Yorkshire light infantry,
2000 years earlier: "morituri te salutant"

"I will be with you, whatever". Blair to Bush, precursor to invasion of Iraq
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#8 User is offline   thorvald 

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Posted 2016-January-10, 06:37

At the 3 card ending the following information is available to West - only based on the actual play

North has a singleton club (He dropped a at trick 3)
North has a least 3 diamonds (He followed 3 rounds)
North started with 3 s as he ruffed a in trick 10
North started with exactly 5 s, neither partner nor dummy could follow the third round of spades

So the actual situation is 100 % known

So there must be a flaw in the GIB software
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#9 User is offline   icer 

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Posted 2016-January-10, 10:07

View Postgoffster, on 2016-January-09, 15:16, said:

when the spade jack is lead at trick 10, it is 100% obvious
to take the queen and lead the club ten.

There can be no second choice whatsoever.

The robot however ducks! Giving up a trick.

This makes me believe that GIB enters a "Dont care" zone
when it realizes the contract cannot be beat, even at matchpoints.

http://tinyurl.com/zcv27gf



so you think GIB is bad?

i hope you can see how GIB plays 4 here:

{comments}

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#10 User is offline   gwnn 

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Posted 2016-January-10, 10:26



Use {hv=http://www.bridgebase.com/etcetcetc}400|300{/hv} but square brackets instead of curly ones.

And yes, wow.

edit: wow squared!! I didn't even see the play in hearts. wtf
... and I can prove it with my usual, flawless logic.
      George Carlin
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#11 User is offline   Bbradley62 

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Posted 2016-January-10, 10:50

View Postthorvald, on 2016-January-10, 06:37, said:

...North started with 3 s as he ruffed a in trick 10...

So the actual situation is 100 % known

So there must be a flaw in the GIB software

You're right! I missed the ruff.
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#12 User is offline   Stephen Tu 

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Posted 2016-January-10, 23:05

Referring to OP's hand, yeah that's really bizarre. Hand is double dummy at that point, GIB shouldn't be getting this wrong. Interestingly I put it into my ancient home copy of GIB, it makes the exact same error. Inexplicable.
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#13 User is offline   Vampyr 

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Posted 2016-January-17, 19:03

View Postgwnn, on 2016-January-10, 10:26, said:

edit: wow squared!! I didn't even see the play in hearts. wtf


Perhaps some disgruntled employee has inserted a misere mode into GIB?
I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones -- Albert Einstein
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