Grosvenor Gambit!

[uva72uva72]

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Match points, ACBL robot individual

 

Yesterday I posted a hand in which I expressed the opinion that misuse of a negative double resulted in a failed grand slam. With regard to this hand, it seems to me that North's failure to make a negative double holding a classic example unnecessarily landed us in an unmakeable contract. I'd be curious to know why North failed to make a negative double and then felt obliged to compensate by raising to the 3-level when I protected in the pass-out seat. To my mind, this auction only makes sense when North holds a club stack and was hoping for a reopening double or holds a hand that a negative double or other bid does not describe (perhaps 2-3-4-3).

 

I said that the resulting 3♠ contract is unmakeable, although several South's did make the contract. It's unmakeable because East is able to give West a ♦ ruff at trick 6, for a total of 2 ♠s, 2♣s and 1♦. At some tables, though, East returned not a ♦ but a ♠. Why, I asked myself, is East not giving partner a ruff. The answer - West has no more ♠ and East didn't return a ♦ to prevent me from seeing West's failure to ruff, overtaking the ♦ in dummy and picking up the ♠ suit via a finesse - kind of like dropping a stiff K offside when RHO fails to overruff the dummy's Q. So, based on this incontrovertible logic, I played East for ♠A10xx and inserted the 9 instead of rising with the K. I was surprised to say the least by the result. However, giving credit where credit is due, I must applaud the programmers for including as sophisticated a defensive maneuver as the Grosvenor Gambit in the robots' arsenal; and hats off to the Souths who refused to be taken in.

[Antrax]

Well played, but you're not playing against a human. GIB would never think "I can't lead a diamond or S will infer something from west's non-ruff", since GIB thinks all four of you can see all hands, it's just the way it's programmed.

I'm not sure why GIB E didn't give W a ruff, though.