[barmar]

Scoring: IMP

You're East, auction is 1NT - 4♥(Texas) - 4♠, partner leads ♣8, plan the defense.

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The winning defense is to switch to a ♦ at trick 2. You have to establish partner's K as a winner before declarer can establish a ♣ or ♥ winner on which to pitch dummy's ♦ loser. But Philip Alder doesn't explain the reasoning behind this -- he just says "This is a tough problem" and "Award yourself ... if you got this one right."

So how do you figure this out at the table? If declare's ♥K were ♦K, this would allow him to discard a ♣ o ♥ loser. The setting defense in that case would be to take your ♣AK and ♥AK.

The only inference I can think of is that partner might have led 4th best from ♥AKxxx. Is this it? But partner chose not to lead 4th best from a long suit in the original hand, and if he'd led away from that suit it would have given away the contract as well, so can't we presume that partner knows better than to lead that suit?

[jdonn]

Uh, partner might have led the A or K of hearts if he had AK against a 4♠ contract. I was about to type a situation where I thought a heart switch would win but I see now I was wrong, I think a heart switch is completely nullo.

[skjaeran]

Unless partner scores a trump trick (with Qxx) you need two red tricks to beat this. Since you can assume partner would lead a red ace from AK in one suit, he won't have that.

If partner has an ace and a king in the red suits you need to switch to the king suit at trick 2 to set up this trick in time (cashing another ♣ set's up a discard, hitting the wrong suit gives declarer time to set up a ♣ trick himself). That's a 50-50 guess. The additional chance is that partner might hold ♦AQ. That makes a ♦ switch better than a ♥ switch - and the correct defence. (And it's not double dummy.)

[Trumpace]

barmar, on Aug 31 2007, 12:08 PM, said:

The only inference I can think of is that partner might have led 4th best from ♥AKxxx.  Is this it?  But partner chose not to lead 4th best from a long suit in the original hand.

4th best from AKxxx against a suit contract?

Without a very very good reason to back it up, that is a ridiculous lead.

[hatchett]

If you swap the position of AK♥s and AK♦s then a heart switch is necessary (actually AK and a third club would work as well), but a ♦ switch would let it through, since west is subjected to a trump squeeze.....Say you switch to a diamond to the K and A and west continues ♣s (best) and east plays a third round, west ruffing to nullify the discard on the ♣Q. Declarer now runs the ♠ suit, reducing to this ending.

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On the penultimate ♠, south throws a low heart and west can choose his poison

[Trumpace]

hatchett, on Aug 31 2007, 12:56 PM, said:

If you swap the position of AK♥s and AK♦s then a heart switch is necessary (actually AK and a third club would work as well), but a ♦ switch would let it through, since west is subjected to a trump squeeze.....Say you switch to a diamond to the K and A and west continues ♣s (best) and east plays a third round, west ruffing to nullify the discard on the ♣Q. Declarer now runs the ♠ suit, reducing to this ending.

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On the penultimate ♠, south throws a low heart and west can choose his poison

What if West ducks the ♦A on the first round?

[hatchett]

If he ducks the ♦K it's easy you draw trumps and play a club to establish a discard for the ♥.

[Trumpace]

hatchett, on Aug 31 2007, 01:02 PM, said:

If he ducks the ♦K it's easy you draw trumps and play a club to establish a discard for the ♥.

Of course. *smacks head*

[barmar]

Duh! For some reason I was thinking NT when I I wrote that about 4th best ♥. So now it all makes sense.

[Free]

It's not as easy for declarer to discard on a ♦. Partner may hold ♦9 in which case discarding is as good as impossible. So switching to ♦ is not fatal if you guess wrong. If you switch to ♥ however, and it's the wrong suit, chances are huge that declarer can discard (QJ in dummy is a high holding). That's why a ♦ is better.

[skjaeran]

Free, on Sep 2 2007, 11:49 AM, said:

It's not as easy for declarer to discard on a ♦. Partner may hold ♦9 in which case discarding is as good as impossible. So switching to ♦ is not fatal if you guess wrong. If you switch to ♥ however, and it's the wrong suit, chances are huge that declarer can discard (QJ in dummy is a high holding). That's why a ♦ is better.

If you switch to a diamond and it's wrong (declarer holding ♥A and ♦KQ) it's fatal if declarer also holds ♠Kxx (or even Qxx). He'll draw trumps in 2 rounds (finessing if holding the queen), and play a ♣, setting up his Q for a heart discard. So that's not the reason why a diamond is best.

If partner holds an ace and a king in the red suits, it's a pure guess what suit to return at trick 2. If you guess wrong he'll make, if you guess right he'll go down. But partner could also have ♦AQ.

[kenberg]

hatchett, on Aug 31 2007, 12:56 PM, said:

If you swap the position of AK♥s and AK♦s then a heart switch is necessary (actually AK and a third club would work as well), but a ♦ switch would let it through, since west is subjected to a trump squeeze.....Say you switch to a diamond to the K and A and west continues ♣s (best) and east plays a third round, west ruffing to nullify the discard on the ♣Q.  Declarer now runs the ♠ suit, reducing to this ending.

Dealer: ????? Vul: ???? Scoring: Unknown

♠ 63 ♥ QJ ♦ 8 ♣   ♠   ♥ K8 ♦ 962 ♣   ♠   ♥ 94 ♦ J7 ♣ 9 ♠   ♥ A3 ♦ Q54 ♣

On the penultimate ♠,  south throws a low heart and west can choose his poison

A nice squeeze, but would declarer do this? Running the Q requires E to hold the K. Playing for the squeeze requires that the K be with the long diamonds (either side, so also about even odds), and that declarer correctly read the position (A first if K is blanked, Ds first if long D is pitched). If we assume that declarer is good enough to find this squeeze should we not also assume defender is good enough to blank his king early on? Declarer will have a hard time explaining his brilliant play if in the end W shows up with one remaining heart spot and E with Kx.