Sitting East-West, we messed up the defense on board 26 at this link Friday night. It was still a topic of discussion on Saturday.

I don't recall the bidding, but I think West opened a third-seat Precision 1♦, North overcalled some number of hearts, and South placed the contract in 3NT. West led the ♦A, which we play as asking for suit preference. Do you play the ♦7 or ♦5 to trick one?

In our discussion this afternoon, South argued that I should have played the ♦5. After a club to my ace and a diamond back, South should lose the first eight tricks for down four.

Perhaps I've been playing too many teams games lately, but I was convinced at the time -- halfway through trick one, remember -- that I should instead play the ♦7, signalling for a spade shift. Looking at this hand more closely, I stand by that initial decision. From East's perspective, it's clear that 1) West has a decent diamond suit headed by at least the ace and king, 2) West is likely to have a black-suit king or the ♠A for the opening bid, 3) South bid a light game, and 4) South has at least one diamond stopper, but it's not clear whether it's positional (♦Jxxx) or absolute (♦J9xx or better).

Suppose, then, that the ♦9 and ♦8 on this board are swapped. If West has the ♣K, a shift to clubs and a diamond back takes the contract down immediately on three top diamonds and two top clubs. But if West has the ♠K, the club shift gives away the contract immediately. We can cash three diamonds and one club, but South can cash 6 hearts, the ♠A, and the ♣KQ for 9 tricks.

Asking for a spade shift is fine. If West has the ♣K, South can cash 6 hearts and two top spades before having to let me in with a spade or club. I had planned to hold on to a diamond as well, ensuring that we would take the last 5 tricks. If West has the ♠K, South can only take 7 tricks before letting one of us in.

In other words, accurate defense will always take the contract down if West leads a spade at trick two, while a club shift only works if West holds the ♣K. Believe it or not, I had actually worked all of this out in the few seconds that I paused while deciding which diamond to play to trick one. Sadly, I messed up by not making a clear signal for clubs later, misleading West into cashing out for 3NT making exactly. But I still think that, based on the information East has at trick one, a request for a spade shift is correct.

In a sectional Swiss, you pick up

♠ AK72
♥ QJT9
♦ A
♣ AKQJ

( a nice hand for onceCollapse )

Interesting hands from last night's Bridge Spot game -- you're bidding Precision at matchpoints, of course:

1. Opps silent throughout, the bidding goes 1♣ - 2♦ - 2 ♥ - 3♦ - 4♣ - 4♦ - 4NT. Is 4NT Blackwood or to play?

2. None vul, LHO opens 1♥, partner overcalls 1NT, and RHO passes. What's your strategy with ♠QJ64 ♥7 ♦J98642 ♣K4?

3. Partner shows a 20-21 NT, and you bid 3♥ as a transfer to 3♠ holding ♠AT852 ♥87 ♦9543 ♣T9. Now what?

The full hands are #22, #1 and #7 here.

After two passes, neither vul at matchpoints, you pick up the following hand at the Watertown sectional:

♠ QJT87
♥ (none)
♦ (none)
♣ KJT98532

What do you open? What is your strategy?
( Read more...Collapse )

In previous posts, we looked at weak and strong preempts in third seat. One conclusion was that the ACBL's weak hand is safe to preempt in third seat except perhaps red-on-white. But what about weaker hands? ( Indeed, what about them?Collapse )

We've simulated 6000 preempting hands and looked at a variety of statistics. This post draws conclusions from the data. ( more bridgeCollapse )

Should 3rd seat open the ACBL's very light preempt example? Should other seats consider it? What about in 1st and 2nd seats? Do very light preempts play well with strong preempts?

The data below are based on 6 runs of 1000 hands in each of the combinations of seat (1st, 2nd, 3rd) and preempt strength (weak, strong). The two hands considered are
♠Q6 ♥Q95432 ♦J85 ♣93 (weak) and
♠4 ♥KJT542 ♦AJ7 ♣983 (strong).
The strong hand is chosen to qualify as a "good good" hand but be too weak to open for most partnerships. ( long entryCollapse )

The ACBL says that the hand
♠Q6 ♥Q95432 ♦J85 ♣93
qualifies as a "very light" preempt. My initial reaction to the hand was that it was too weak to preempt except possibly in third seat white on red, and even then only if I'm sufficiently caffeinated. But I'm often too conservative in bidding, so my judgment may fail me on such questions.

Fortunately, it's easy to churn through lots of deal simulations. I recently downloaded Deal 3.1.9, Thomas Andrew's deal simulation software. It lets you define and specify constraints on hands. You can even run a double-dummy analysis of the deal and calculate the par score on a hand.

I'll get to the very light preempt in the next post, but first I'll discuss a few details regarding the simulations. ( more detailsCollapse )

Both Standard American and WMCB Precision provide a way for opener to describe a 20-21 HCP balanced hand. On marginal balanced hands, when should responder raise to 3NT? Thomas Andrews has done a large number of simulations, which are summarized in these tables. As a caveat, his simulations are for double-dummy results at notrump only and therefore do not consider possibilities of defender error, declarer error, or improvement via (garbage) Stayman, but the conclusions may still be useful. Memorizing all the possible distributions is beyond our capabilities (beyond mine, at least), so I attempt to distill the results down to summarize the probabilities.

With 3 HCP, do not bid game.

With 4 HCP, count your tens. The threshold is 2 tens, or 3 tens if 2 of your HCP are in jacks. If you are above this threshold, bid game. If you are at the threshold, bid game at IMPs. If you are one ten below the threshold, bid game at IMPs only if vulnerable.

With 5 HCP, always bid game at IMPs. At matchpoints, bid game with 1 ten or 2 tens if 2 or 3 of your HCP are jacks. Bid game if you are at or above the threshold.

With 6 HCP, always bid game.

These cases can be further condensed as follows: With 4 or 5 HCP, add 0.5 HCP for each ten and subtract 0.5 HCP if you have at least 2 jacks. Then,

>= 5.5 HCP accepts all games.

5.0 HCP accepts all IMP games.

4.5 accepts vulnerable IMP games only.

<= 4.0 HCP rejects all games.