Monday, November 9, 2009

Board 39

Board 39 (click to download pbn file)
Both sides vulnerable

♠ A K 10 3 5 4 Q 5 3 ♣ Q J 7 4

I open one club in first seat, partner responds one diamond, and RHO overcalls with one heart. I bid one spade, and partner bids three notrump, which ends the auction. West leads the three of hearts.


NORTH
♠ A K 10 3
5 4
Q 5 3
♣ Q J 7 4






SOUTH
♠ Q 7
K J 6
A J 9 6 4
♣ 9 8 3



WestNorthEastSouth
1 ♣Pass1
1 1 ♠Pass3 NT
(All pass)

Partner seems to be pretty aggressive with these three notrump bids. I'm not sure what was wrong with two notrump. I play the four from dummy, and East plays the ten. Falsecarding with the king wouldn't work too well here. West has no reason not to play hearts from the top once he gets in. So I win with the jack. I know from the lead that hearts were five-three.

I have essentially two ways to make this: (1) Hope West has all the missing high cards. I play diamonds out of my hand. When West is in with the king of diamonds, he can't afford to clear hearts, since that gives me my ninth trick. So I have ample time to establish my ninth trick in clubs. (2) Try to run the diamonds. I cash out the spades, then lead the queen of diamonds from dummy, hoping West has ten doubleton or East has king-ten doubleton.

Neither line is especially good. Which one is better? Let's start by assuming diamonds are three-two. (We'll relax this assumption later). In that case, line (2) is easy to calculate. There are 20 possible three-two breaks (the combinations of five things taken two at a time--times two, since either hand can have the doubleton), and our play works in four of them (three doubleton tens in West's hand plus one king-ten doubleton in East's hand). That makes line (2) 20%. Line (1) is little harder to calculate. It works when West has three out of three critical cards. Normally this would be 12.5%, but it's better here because some layouts are contra-indicated by East's failure to raise hearts over one spade. Let's assume East can't have all three honors, that he can't have the ace-king of clubs, and that he can't have the ace of clubs and the king diamonds. We'll allow him to have both minor-suit kings. This is a simplification. Depending on his shape, he might sometimes pass with the club ace and the diamond king and he might sometimes bid with both kings. But it's a reasonable approximation. We've eliminated three of the eight possible ways for the honors to be split. So West will have all the missing honors one time out of five, making line (1) also 20%.

In our first approximation, then, both lines are roughly equal. Next we consider what chances each line might offer above what we've already calculated. Line (1) will work on certain four-one diamonds breaks. Specifically, it will work when West has a singleton king or when East has either singleton honor and West has both club honors. Line (2) has an advantage that's hard to quantify, namely, flexibility.  Depending on what happens when you cash the spades, you may change your mind about how to play diamonds.  You may wind up leading a diamond to the jack, essentially reverting to line (1) with some extra chances against king doubleton of diamonds on your right.  And if the jack of spades happens to fall, allowing you to put pressure on the opponents by cashing four rounds of spades, additional possibilities arise.  I decide I like line (2).  Line (1) is too committal.  When you stay flexible, good things tend to happen.

I cash three spades, pitching a club from my hand. East plays deuce--four--five. West plays nine--six, then discards the deuce of hearts. So West is already under pressure. What's going on?

____

West might be 2-5-4-2 with ten fourth of diamonds. He might also be 2-5-3-3 with ten third of diamonds and ace-king third of clubs. It's not immediately obvious that he can't afford a club from the latter hand. But, in fact, he can't. After leading the queen of diamonds to the king and ace then cashing the jack, I can simply exit with a diamond, and he has to give me my king of hearts for my ninth trick. To escape the endplay, he must keep an exit card in clubs.

One thing for sure. He doesn't have the ten doubleton of diamonds I was about to play him for, since has no reason not to pitch a club from four. So I'm changing my mind about leading the queen of diamonds. Suppose I play a low diamond to the jack, cash the ace, presumably dropping East's king, then play a diamond to dummy's queen and exit with the queen of clubs. I've taken seven tricks. I need only two more, and West must give them to me.  He can either play hearts, giving me an entry to my diamonds, or he can play clubs, giving dummy two club tricks.

I play the three of diamonds--seven--jack--deuce. Ace of diamonds--eight--five--ten. Ten? That's disappointing. I was sure this was going to work. I play the eight of clubs. West hops with the king, cashes the diamond king and the club ace, then plays a club to dummy. I have to lose the last two tricks for down one.


NORTH
♠ A K 10 3
5 4
Q 5 3
♣ Q J 7 4


WEST
♠ 9 6
A Q 9 3 2
K 8 2
♣ A K 6


EAST
♠ J 8 5 4 2
10 8 7
10 7
♣ 10 5 2


SOUTH
♠ Q 7
K J 6
A J 9 6 4
♣ 9 8 3



When West didn't pitch a diamond, I thought he had ten third. But he had king third, and the reason he couldn't afford to pitch one was he needed to duck the first round. Nice play. It turns out line (1) would have worked. But I still think line (2) is better.  There's no particular reason the king and ten of diamonds couldn't have been reversed.

I was impressed with Jack's defense.  Assuming I work out to abandon my original plan of leading the diamond queen, this defense was necessary. He had to hold a diamond so he could duck the first round, and he had to hold a small club to avoid being endplayed. I gave this problem to several gargoyles, and no one found this defense. For once, I think I went down against Jack when I might have succeeded against most humans.

At the other table, the auction and lead are the same. Jack wins the jack of hearts, cashes the spade queen, and, strangely, leads a club. West hops with the king and plays ace and a heart. Declarer plays another club. West hops with the ace and cashes his hearts. Declarer has the rest. Down one for a push.

I'm not sure what Jack was up to. Did he consider it so unlikely he could make this hand that he was simply playing to hold the undertricks? It's true that, if you give East one of West's club honors, Jack would have been down two, while I would have gone down five, losing seven imps. I risked a lot of extra undertricks for a line that had little chance of working.  In this case, perhaps my customary single-minded devotion to finding a way to make the hand was wrong?  Perhaps Jack's line makes more sense?

I don't think so, at least not under normal conditions.  The game is thin, and you have no reason to expect your opponents to reach it at the other table.  If your opponents are going plus at the other table, the cost of going down a few extra tricks is minimal compared to what you rate to pick up by making the game.  In this match, however, the same South is sitting at both tables, and all of my own actions were routine.  So maybe it's fair to assume they will reach game at the other table as well.

Me: -100
Jack: -100

Score on Board 39: 0 IMPs
Total: +96 IMPs

4 comments:

  1. "In this march, however, the same North is sitting at both tables..."

    the same South

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  2. If Jack "thinks" by generating hands and calculating the double-dummy result, then its decision to play for down 1 was automatic. It would have decided that making this game was <20% on either of your two lines, and that its line would win 7 IMP whenever either both club honors were with West or when west had a singleton club honor. Given that East would have surely raised hearts with 10xx in support and C-AKxxx, then the combined chances of this line probably approach 40%. Since going down 1 while one of the desperation lines results in a make loses 12 IMP, the break-even for Jack's line is when his line is 12/7 x more likely to save the three undertricks. If your line is 20%, this would require Jack's line to save the undertricks about 34& of the time.

    We, as humans who are responsible to our teammates, tend to overvalue the desperation plays to avoid the painful explanations. Jack has no such inhibitions. I have seen GIB make similar decisions.

    Also, I can see why it bid 3NT on that airball - it could see that 2NT was nowhere near certain, so it was willing to accept a game contract with far less than the usually accepted chance of success.

    Computer bridge has a long way to go before it begins to mimic the thought processes of strong players. But perhaps some day, strong players may begin to think more like computer programs. This is already happening in chess, where virtually all strong players use Rybka or similar software to analyze both their games and their opening lines.

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  3. I disagree with the math, and thus with the line of play. West knows that South started with at least KJx of hearts, and KJ10x is not unlikely.

    With one outside entry, is West going to try to set up hearts? No. The lead may give you your ninth trick. With two outside entries, maybe. With three outside entries, of course you lead your longest suit.

    But there is another factor. Say West doesn't have the king of clubs. What will he do if you give him the king of diamonds? Duck. He wants more information from partner, and letting you take one more fast diamond trick doesn't hurt.

    If you take the diamond finesse, you are exposing yourself to losing two diamonds. If you play West for the king and he has it, you are basically home free--even on hands where East has a club honor, West will win the second diamond and lead another heart. Cash out for making three.

    Does East have a way to signal for a shift? Not really. You could play the 10 of diamonds then the 7, but would partner read this as a signal to shift or as giving count? Should West cash the club ace, assuming he has it but not the king? No. As it happens East will signal for a continuation, but there are many hands where declarer has the club king and not the spade queen, and now you can't set the contract.

    Was West wrong to play this way? Not really, switch the jack and queen of spades and you are not making.

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