Thursday, July 2, 2009

Sequel: Play it better than GIB

After the auction begins as in the previous post, you arrive in 4S with:

Dummy: A75 J93 K843 KT8

Declarer: KJ643 A62 AJ2 93

This is not one of the ideal combinations you were hoping for, but you still have play. The early play goes:

CQ, K, A, 3

Club, 9, J, 8

Heart, 9, Q, A

S3, 2, A, 9

CT, small, H2, small

S5, T, J, Q (sigh)

S8, 7, club, K (new life?)

Yes, there were some layouts where a diamond hook at trick 6 is better, but if trumps come in you’re probably making it without the D hook, so playing trumps looks right. Your bidding convinced lefty you were 5-2-4-2, so he didn’t cash the setting trick with HK (wrong of him, since on that layout the pitch he set up would be useless.) Now, here you are needing the rest with:

Dummy: --- J3 K843 ---

Declarer: 64 6 AJ2 ---

Any chance?

Most of you know that GIB’s algorithm for single-dummy play is to generate lots of random hands, then see how to make it double-dummy. It thus tends to miss plays that “steal” tricks in single-dummy play. Here, like a good GIB, I calculated that the only legitimate chance was for rho to have T9 tight in diamonds. Then I have 9 tricks with the backward finesse, and LHO with his presumed HK is squeezed out of his Q76x in diamonds for 10. So, I cashed my trumps pitching hearts; unfortunately no diamonds were pitched, so it was clear there had been no squeeze. Knowing it was unmakeable, I just played DK, diamond hook to try for down 1.

Did you see the play that, GIBlike, I missed? Just lead the DJ from hand. If lho has Qxx (no T), you’ll make it for sure – no way will he cover when he thinks you have AJTx and are trying to tempt him. This also retains the tiny legitimate squeeze chance I mentioned.

In practice lho had Q and T of diamonds, so nothing works, except stopping in 2 or 3 spades!


Franco said...

It seems like there's probably a (slightly) better line. Assuming no singletons, I get 42% for your line (50% spade hook x 83.3% 3 more red tricks)

Perhaps something like (after winning HA):

SK, SA. 40% chance Q drops, then go for 3 more red tricks (pitch heart, SJ, heart up, fall back on diamond hook). I'm up to 33.3%

No SQ: now try D hook and hope for Qxx onside. Odds of that are a bit over 20% with all the splits we've already observed, so that gets this line over 45%.

Jonathan Weinstein said...

Yes, I considered that also, but I thought lefty was even more than the abstract 2/3 you are giving him for the HK...righty's trick-2 play (made rather promptly) of clubs rather than hearts is odd and suggests Q only not KQ hearts.