Saturday, November 7, 2009

The Monthly Trout?

Sorry for the long absence.

I've been reading Jeff Rubens new book, _Expert Bridge Simplified_. I quite liked it. A lot of it I was already familiar with (but anyone that isn't would likely benefit a lot from that material), but the stuff that was new to me (e.g. estimating the chances that 2 suits will break such that the same opponent is short in both) was really cool. Even for the stuff I was familiar with, it really cemented some important stuff in my mind. How often this material will actually help me, I'm not sure, but I'll try to pay attention.

The subtitle is "arithmetic shortcuts for declarer" and it focuses a lot on choosing approximately the best line. Many problems go to a lot of trouble for an ultimate answer of "who knows" or "you could work a lot longer on this to get a precise answer, but I [JR] am not interested". Also, often it's about convincing yourself you have the best line without necessarily knowing how good it is overall or how much of an improvement it is over the alternative.

So, there were a couple of deals where I thought there was a bit more of interest than JR brought up, but it was within the spirit of the book not to bring it up. Here's one example:

A K Q 10 3
10 9 8
10 9 8 7
A J 3 2

After starting 2♣ you wind up in 7N and get a diamond lead. How do you play?

The solution from the book, and my own are both below.

The books solution was to point out that you should play for spades to come in and if they don't you have to choose between a finesse and a squeeze. The squeeze requires the 2 card psuedo-suit of outstanding-major-suit-honors to split 2-0, a bit less than 50%, while the finesse is a straight 50-50 shot and so better. He explicitly says he's not bothering to consider possible info learned from the minor suit distributions because it's too complicated.

In a variant on this problem, that was true, but I think here it's not that hard. You can learn about both minors and most of the spade info before making your final decision: run diamonds (shake a spade) and 3 clubs, then 2 spades (shake a heart) and play a 3rd spade. After seeing East's play, you have to decide whether to unblock clubs and play for the squeeze, or pitch another heart and play for the finesse.

Case 1: RHO shows out, LHO has 5 spades. If the 11 outstanding minor suit cards break 4=7 it's a pure guess based on open spaces. If they break worse, play for the squeeze, better play for the hook.

Case 2: RHO follows. Assume LHO is about to also follow small -- if he shows out then the finesse and squeeze have the same odds (both require RHO to hold HK). Now we know 17 cards (all the minors and the spade spots). If LHO has 6 open spaces (minors break 4=7), then the squeeze is 6/9 * 5/8 + 3/9 * 2/8 = 1/2, while the finesse is only 1/3: play for the squeeze. If LHO has 5 open spaces, then 5/9 * 4/8 + 4/9 * 3/8 = 4/9, the same as the finesse.

This seems to be worth only 1 or 2%, but is not that hard to work out at the table.

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