[pilowsky]

I've had a string of hands where I made the wrong choice - not completely unusual - but was wondering if the odds were really that bad.
With South playing the ♥7, and West ducking, what are the chances that East has the King, West has the Jack, and putting up the Ten, is the right play?

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[dokoko]

king in East = 50%
jack in West = 50%
low to 10 right play = 100%

all together = 26%

[AL78]

Playing the ten has to be the correct play as it allows you to play the suit for no losers on most layouts where West holds both missing honors.

If it failed badly on this hand, move on. I've had sessions where I repeatedly have a choice of plays and like guided radar head for the wrong one on the layout, and end up with 43%.

[Cyberyeti]

AL78, on 2022-December-31, 02:59, said:

Playing the ten has to be the correct play as it allows you to play the suit for no losers on most layouts where West holds both missing honors.

If it failed badly on this hand, move on. I've had sessions where I repeatedly have a choice of plays and like guided radar head for the wrong one on the layout, and end up with 43%.

This is actually quite complicated in context with the rest of the hand and the presence of the 8, particularly as to what you do on subsequent rounds and whether RHO should ever false card to try to induce you to leave the A in dummy with no entry.

[AL78]

Cyberyeti, on 2022-December-31, 05:35, said:

This is actually quite complicated in context with the rest of the hand and the presence of the 8, particularly as to what you do on subsequent rounds and whether RHO should ever false card to try to induce you to leave the A in dummy with no entry.

I was thinking of merely taking the double finesse then cashing the ace if the nine does not appear. This makes four tricks if East has a void, singleton nine, 9x or 9xx. I guess RHO might try and peter with 9xx to try and induce a failing third round finesse.

[sfi]

AL78, on 2022-December-31, 06:50, said:

I guess RHO might try and peter with 9xx to try and induce a failing third round finesse.

There aren't enough small cards for this to work. LHO has to start playing honours on round two of the suit.

[LBengtsson]

I think what is confusing the matter here is the presence of the ♥8 in dummy. If it were ♥765 opposite ♥AQ10 it would always be correct to finesse the ♥10 on the first round. To me, this is basic technique, that given the choice of two finesses with dummy's cards, without any knowledge, you always play the lower card, the ♥10 on the first round except if an honor is played by West.

[dokoko]

LBengtsson, on 2022-December-31, 15:41, said:

I think what is confusing the matter here is the presence of the ♥8 in dummy. If it were ♥765 opposite ♥AQ10 it would always be correct to finesse the ♥10 on the first round. To me, this is basic technique, that given the choice of two finesses with dummy's cards, without any knowledge, you always play the lower card, the ♥10 on the first round except if an honor is played by West.

Think of such combinations in the following way. You try to win as many tricks in 3 rounds as possible. Depending on what happens on those tricks your 4th card in dummy will be a winner or not.

If you finesse the 10 then the Q you make 3 out of 3 if KJ is onside and 2 out of 3 if either K or J is onside but not both. If you start finessing the 8 you cannot improve on that but lose an extra trick when your 8 loses to the 9 and the J would have been onside.

You don't plan to take three finesses in the suit, as you may finish getting no heart trick at all. So the ♥8 is what is sometimes called a "disturbing card" - you know how to play xxx opposite AQTx, so the fact that dummy's x is the 8 is purely incidental.