[uva72uva72]

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IMPS, ACBL robot individual

I think this is the highest percentage contract I have ever failed in. Those who are better at calculating these things will doubtless be able to come up with a more exact figure, but I think that winning the ♦ lead in dummy and playing a trump toward declarer's hand immediately (intending to finesse against the Queen) offers better than a 98.5% chance of success. My thinking is that this line makes if:

Diamonds are not 4-0 (meaning I can eventually ruff a club in dummy for trick 10) = 90.43%, or
Diamonds are 4-0 but onside with ♥s and ♦s not breaking viciously = ~4.3% (a bit less than 50% of remaining 9.57%), or
Either K or Q of ♦ is onside = ~3.3% (75% of remaining 5.27%), or
♥Q is doubleton, or ?.?%, or
Club/Heart Squeeze Operates ?.?%

On the actual lie of the cards, I believe it works to play a ♣ to the 10 immediately, precluding East from drawing trumps before a ♣ can be ruffed in dummy. But is that a higher percentage line?

[uva72uva72]

My previous post should read "Either K or Q of ♣ is onside"

[gnasher]

You missed out the possibility of losing a spade finesse and then suffering a diamond ruff, which is about 0.5%.

I wouldn't give much for the club-heart squeeze. In the ending you reached, you'd have to be very confident of your card-reading to play for East to have been squeezed.

At tick two, what about playing ♣A, club? That appears to guarantee the contract unless they ruff ♣A or arrange a red-suit ruff. East passed in 3rd seat at favourable, so is unlikley to hold ♥Qxxxxx.

This post has been edited by gnasher: 2014-August-24, 02:26

[gordontd]

 uva72uva72, on 2014-August-24, 00:32, said:

I think this is the highest percentage contract I have ever failed in.

Since it's a robot tournament it's more about what the rest of the field are doing than about the success or failure of the contract, and by your off-centre opening you've ensured it's played the other way up than normal. I think playing it by South and getting a Gib-passive club lead and heart return would direct you towards ruffing a club in hand once you discover the trump break, rather than trying anything else.

[Bbradley62]

 gordontd, on 2014-August-24, 02:42, said:

Since it's a robot tournament it's more about what the rest of the field are doing than about the success or failure of the contract, and by your off-centre opening you've ensured it's played the other way up than normal...

OP wasn't commenting on his IMP score, he was commenting on the fact that he went down in a high-probability contract, regardless of what kind of score that yielded. The outcome appears to have nothing to do with which side the hand was played from; the successful declarers (from both ends of the table) made sure they got a club ruff rather than allowing trumps to be played 4 times. They made 3 natural trumps, 1 club, 1 club ruff, 3 diamonds and 2 hearts for 10 tricks, as Gnasher suggests.

[uva72uva72]

Thanks. My actual question had to do with whether running the ♣9 at trick 2 is a higher percentage line than playing a trump. Math tables tell me that the 7 outstanding ♣s will split 6-1 6.78% of the time, risking a club ruff more often than trumps will lie 4-0 offside. I just don't know how that risk factors into the overall likelihood of making the contract with that line as compared with the line I chose. Then, of course, there is the suggested line of playing a ♣ to the Ace and another ♣, which potentially brings into play the ♠6. For the record, all Souths who received a ♣ lead and ducked it to the 9 made their contracts (although the subsequent defense was not at all challenging); none of the Souths who won the first club played another immediately, and none made their contracts. The only North declarer who succeeded got nullo defense. No North declarers led a ♣ at trick 2.

A very challenging hand.

[Bbradley62]

 uva72uva72, on 2014-August-24, 00:35, said:

My previous post should read "Either K or Q of ♣ is onside"

And the first two conditions, referring to a suit breaking 4-0, are about spades, not diamonds.

[Bbradley62]

 uva72uva72, on 2014-August-24, 15:56, said:

Then, of course, there is the suggested line of playing a ♣ to the Ace and another ♣, which potentially brings into play the ♠6.

I don't see what ♠6 has to do with it; you are going to ruff the third club with ♠10, so that if you get overruffed you will get 4 natural spade tricks in North instead of the 3 we originally counted. The plan is to allow for the loss of a club and two spades, but one of those spades might actually be an overruff on a club trick.

[gnasher]

 Bbradley62, on 2014-August-24, 18:12, said:

I don't see what ♠6 has to do with it; you are going to ruff the third club with ♠10, so that if you get overruffed you will get 4 natural spade tricks in North instead of the 3 we originally counted. The plan is to allow for the loss of a club and two spades, but one of those spades might actually be an overruff on a club trick.

If you ruff the third club with ♠10, then take a losing spade finesse, they may play a fourth club, overruffed with ♠6. My line actually looks like a way to go down when everything is breaking, so I prefer the original poster's line.

[Bbradley62]

ok. I was thinking that after the third club, it would be right to cash all the red winners, throwing North's fourth club.

[msjennifer]

Playing " pairs " there is no time to calculate the percentages.This may be one unlucky hand which could have been made almost double dummy by a HAMMAN,GAROZZO OR FORQUET and not the lesser mortals.Percentages go on changing as the cards are played to every trick. One must not be a slave of percentages.

[1stpanda]

Ah, you're a piker. In a sectional in Pennsylvania a few years ago, my partner and I bid to 7NT with partner on play.

Dummy
♠AKQ10xx
♥void
♦ K10x
♣ A10xx

Declarer
♠8x
♥AKxx
♦AQ9xxx
♣K

The opening lead was a club. (If they lead any other suit it's cold.) But clubs was the unbid suit.

Partner ran this around to his K, as would anybody. Then he led a spade up. Club pitch on his left.

Then he called for the ♦K. Heart pitch on his right.

So he passed the ♦10 to the J and we scored up -50. This turned out to be an 80% score for us, as the field was playing spade slams doubled. Even 6♠X -1 lost to our score.