Double dummy defense
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It is not that often when you find a hand where as a defender you can identify a double dummy defense, virtually from trick one. It helps if you can quickly infer the hand of declarer. This hand came from the recent online NABC.

South
10642
A
QJ74
AJ54
W
N
E
S
1
P
2
P
2
P
3
P
P
P

This is from a bot game, the rules of which are that South (the hand held by the human at the table, has the biggest hand at the table. Other hands may hold as many points, but none may be bigger.

In 4th seat, I have 12 points. Most of the time, my hand is always the first to bid, since my hand is always the best at the table. With only 12 high card points, that leaves little room for the other hands to open the bidding unless it is a preempt. So I am surprised to see two bids before I have a chance to "speak", both of which show at least some values. West dealt, opening 1, and East made an inverted minor raise to 2.

I have no bid to make here, especially since I know that partner must be almost broke. Given my 12 points, each of my opponents can have at most 12 points each, which leaves partner with an absolute minimum of 4 points, but also a maximum of perhaps 7 points. The bidding dies out at 3, partner leading the spade queen. A truly enlightening dummy comes down.

East
97
J5
AK10986
Q93
South
10642
A
QJ74
AJ54
W
N
E
S
1
P
2
P
2
P
3
P
P
P

When I try to teach students about how to play a hand, I tell them that now is the time to do some serious thinking. What can we infer about declarer's hand? What can we infer about partner's hand? Consider the bidding, the opening lead, and what you see in dummy. The good news is, this is a bot game, so I have no impatient opponents to deal with as I put my thoughts together.

East
97
J5
AK10986
Q93
South
10642
A
QJ74
AJ54
W
N
E
S
1
P
2
P
2
P
3
P
P
P

First, we see a 6 card diamond suit in dummy. But West opened 1. A light bulb should appear. Declarer has EXACTLY 3 diamonds, and opened 1. Therefore declarer is 4=4=3=2, thus 4-4 in the majors, and exactly 2 clubs. That is the only hand shape that opens 1 on a 3 card suit. As well, we know that declarer cannot have less than 3 diamonds, since then they would either have a 5 card major, or more than 2 clubs.

How many points does declarer have? They opened the bidding on a balanced hand. Would West have done that on 10 points, with a weak diamond suit? The description indicates 11-21 high card points, so 10 is out. I don't know if West-bot would always have chosen to open any 4432 11 count, but 11 or 12 are the only cases I need to consider.. East has 10 points, so that leaves 40-12-10-(11 or 12) = 6 or 7 points for partner-bot.

Once we know the West shape, we also know the shape of partner. Partner must be 3=6=0=4, just by subtraction.

Partner led the spade queen, from a 3 card suit. Had North-bot held something like KQx, I gather even the bots will lead the king. Had North held AQx or AQJ, I predict it would choose another, safer lead. This leaves me pretty confident that North held exactly QJx in spades. But I know that North has 6 or 7 points, exactly 3 of which are in spades.

The missing honors on the other suits are the heart KQ and the club king. Partner has 3 or 4 more high card points, but NOT 5 or 6 points, and NOT 2 points.  (Remember, West cannot have as much as a 13 count.) So partner cannot hold two of those honors, and therefore, they cannot hold the heart queen. That tells me that partner has exactly one of the round suit kings, and no other honor.

Back to West. We should see two possible hands for West.

West
AKxx
Qxxx
532
Kx

West
AKxx
KQxx
532
xx

Which one is consistent with the bidding? West rebid 2, not 2NT. With the former hand, thus in the 12-14 point range, and values in all other suits, 2NT would probably have been the choice. With the latter hand, 2 seems reasonable. It is described by the bots as 11-21 HCP, 12-21 total points, 3+ diamonds, a stop in hearts, and forcing to 2NT.

All of this leaves me able to pretty well infer the hands around the table.

In our mind's eye, we should see this layout:

West
AKxx
KQxx
532
xx
North
QJx
xxxxxx
Kxxx
East
97
J5
AK10986
Q93
South
10642
A
QJ74
AJ54
W
N
E
S
1
P
2
P
2
P
3
P
P
P
D
3 West
NS: 0 EW: 0

About the only card of any interest we cannot place is the heart 10. I cannot yet place the club 10 either, but it seems less relevant at this point. The heart 10 is probably in the North hand however, since there are two unknown heart spots in West, and 6 heart spots in the north. That puts the 10 with 75% probability in the North. Similarly, North is a 3-2 favorite to hold the club 10.

Partner led the spade queen. Declarer will probably expect 5 or even 6 diamond tricks, 2 spades, and 2 hearts, on any normal trump break. Of course, we know there are 2 trump losers, so only 8 tricks. Declarer will need to find an extra trick, and that will probably come from a club ruff, unless declarer happens to also have the heart 10.

At trick 1, declarer-bot plays the 9 from dummy, winning with the ace as I play low. It leads a diamond towards dummy, as partner-bot plays a heart spot - the 6. Bots don't signal in general, and when a spot is seen as not relevant to later play, it will be chosen randomly.)

In dummy at trick 3, declarer leads a low club through me. It can never help to play the ace, since that will give declarer the option to later lead a club towards Q9 in dummy. And since I firmly believe that partner has Kxxx in clubs, I decide not to insert the jack. Second hand low applies here. The 8 draws the 10 spot from partner, who continues with the heart 9. Low from dummy, but I have no choice but to win the stiff ace.

We are now left with a choice. What card do we return? While we want to kill a club ruff, it feels like any diamond that we exit with costs one of our trump tricks. (Back to that later.) But suppose we exit with a club to partner's king? We can get a heart ruff then, and still a diamond winner, though declarer will be able to ruff that blasted long club in dummy. The result will be to set 3 by one trick, with two clubs, one diamond winner, the heart ace, and a heart ruff.

A spade exit seems to work the same. Declarer will win the king, then exit with a club. Partner can still give me my heart ruff, but declarer has the timing to get a club ruff. So down one again.

Go back and look at the idea of a diamond exit though, with the diamond queen. That will force out the other top trump in dummy. Declarer exits with the club 9, to my jack. Now I pull the last of declarer's trumps with my second diamond honor, while I still hold the 7. Exit with a low club to partner's king, and partner should give me a heart ruff. Counting our defensive tricks on this line, I see 3 clubs, the heart ace, a heart ruff, and one top diamond. We can set 3 by two tricks on this line.

Of course, declarer has another way to play, when I exit with the diamond queen. Suppose he wins the king, then tries to cash the heart jack? If I have a second heart, then it will win, and declarer can go to the spade in hand, cashing a third round of hearts to pitch a club. I had the stiff ace of course, so I could just ruff, cash the jack of diamonds, then we take two more clubs, again, down 2.

Similarly, declarer might decide to win the diamond, then exit with the diamond 10 to me. This kills the clubs ruffs, so this line transposes into the others, where we can cash two more clubs, then I finally get my heart ruff from partner.

One final line to consider, is if declarer ducks the diamond queen! Now I cannot safely continue another round of diamonds, since declarer will make an overtrick, drawing my last trump, cashing the heart jack, then play a spade to the king. Two more high hearts will remain, to pitch clubs, as I will be out of trumps. This seems a killer for our defense. Or, is it?

I have a resource if declarer ducks that diamond. Just exit with a spade. That kills the late entry to the heart winners, effectively killing dummy. No matter what declarer tries, we can always maneuver to get my heart ruff, whereupon I can then draw a third round of trumps so we can get all of our club winners.

For the whole hand, click on the link below, where you can follow the defense by clicking on the next button.

http://tinyurl.com/yatqta56

3, -2 was worth 91.3% on the board, while setting 3 by one trick dropped the score to 43.48%.

By the way, it looks like the location of the club 10 was actually quite important, since partner needed a second entry on many lines.

Was this an easy hand to visualize down to the last trick? Perhaps not so. But once you make those first few inferences, you can predict that declarer desperately wants to ruff a club. Then you can think about how to stop the ruff.

West
AK83
KQ72
532
82
North
QJ5
1098643
K1076
East
97
J5
AK10986
Q93
South
10642
A
QJ74
AJ54
W
N
E
S
1
P
2
P
2
P
3
P
P
P
D
3 West
NS: 0 EW: 0