[1eyedjack]

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MP, Instant, 34
Notwithstanding the explanation for 4S, I read it correctly as 6-5. May I suggest that the explanation be updated? Unless, that is, you can construct a hand with only 3 Diamonds that could reasonably bid this way.

Incidentally East's duck of the Club Ace, particularly at MP, when the hand is an open book, is something of a beginner error.

[Bbradley62]

Is the ♦J play really best, or is it just a small sample size for simulations? Seems to me that playing from top wins whenever diamonds are 3-2 or East holds Qxxx, which should be clearly better than 50%.

[1eyedjack]

Bbradley62, on 2015-June-28, 20:10, said:

Is the ♦J play really best, or is it just a small sample size for simulations? Seems to me that playing from top wins whenever diamonds are 3-2 or East holds Qxxx, which should be clearly better than 50%.

If East holds Qxxx then neither play gains. When they break 3-2, the finesse gains when West has Qxx, the drop when East has Qx and neither gains over the other in other 3-2 breaks. West holding Qxx is slightly more likely (in a vacuum) than East holding Qx.

It is beyond my abilities to play by simulations, and I deal with most suit combinations by rote learning and memory. In this case I applied the old "8 ever, 9 never" often misused rule of thumb.

I believe that the more common beginner error is to cash one from the top to cater for Q singleton offside and then finesse. But that line is best only of you can then repeat a successful finesse, which requires South to have a third Diamond (and North one fewer) and sufficient entries. As West is more likely to hold Qxxx than East holding Q singleton, it is best (in a vacuum) to take two finesses (ie to cash one honour first only if there remains the possibility of 2 finesses afterward). This gains when West has Qx(x(x)) and loses (to playing from the top) when East has Q(x). West's holdings are a bit more frequent in total. I could have preserved an entry to South by deferring drawing the last trump (at minor additional risk of an adverse ruff), but there is no escaping the unchangeable fact that South was dealt only a doubleton Diamond.

It is not quite a vacuum here, but I am open to persuasion that we have sufficient additional information to depart from the bog standard play.

[Stephen Tu]

I think BBradley didn't pay attention to the first few tricks of the play, where the defenders blew up their trump trick, and declarer drew trumps but can no longer ruff out diamonds when that is possible. Of course after that start finesse is best.

Diamonds from top intending to ruff out diamonds is normal on some different lead, like a heart, when you just played two top spades, have a spade loser but still a spade to ruff with.

[Bbradley62]

Yes, I didn't catch that South was out of trump. And I also didn't catch that human was playing the hand. Not sure what I was thinking about there...