kenrexford, on Apr 29 2009, 12:52 AM, said:
But, I think there's more to the mathematics than just analyzing the likely splits for LHO. The possibility of a squeeze has to be relevant, for whatever numbers these generate. Maybe the chance of that is too small to make a difference, but it has to mean something.
As I understand it, you're suggesting drawing two trumps then, when LHO has three, drawing the last turmp and taking a heart finesse.
Finessing gains when LHO has
♥xx, or
♥x and the squeeze works. It loses when LHO has
♥Jx,
♥Jxx or
♥Jxxx. So:
Finesse gains: 7.52 x 2/3 + 2.64 x 5/6 x p(squeeze)
Finesse loses: 7.52 x 1/3 + 8.8 x 1/2 + 4.62 x 2/3 = 9.99
Not even as fine a technician as Ken can make p(squeeze) be greater than 1. It's probably closer than I implied before, but that gives an upper limit for the finesse line suceeding of 6.11, so it's best to play hearts from the top. The probability of a squeeze working following the finesse isn't relevant.
Quote
If you do go back to various points earlier in the play, then I think the 9 in spades also make a difference. If, when you play the spade King, you see no honor drop (neither the Jack nor the 10), then the possible layouts for spades change. You now have an initial start of Jx-10x, J10x-x, or x-J10x. At that point, the odds change somewhat from ab initio possibilities.
If you see an honor drop, barring falsecards, the possibles change as well. More importantly, perhaps, is when LHO drops an honor. This give Declarer an additional possibility of ruffing a heart high before finessing spades. Thus, Declarer could see the Jack or Ten to his left, play heart-heart, ruff a heart high, and then hook the 9 back to hand. Sure, LHO can counter with a J or T play from J10x as a strangely interesting and sexy falsecard, which works wonders when LHO has Jxx(x) in hearts, but this possible line also needs assessed.
At the top of this page it says "Advanced and Expert-Class Bridge". My advanced or expert opponents are defending a grand slam, so it's reasonable to assume they're trying their hardest. Falsecarding from J10x is a well known tactic. It's likely that my LHO will know from the bidding that I have a heart suit, and will envisage the possibility that I need to ruff one in dummy. I know that most of us don't play compulsory falsecards as often as we should do, but I really don't think you should infer much from the play of the jack or ten here.