[kgr]

MP's

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Small ♣ lead for ♣Q and ♣A.
Is it best to finesse ♦ OR play ♦A and hope for ♦K singleton or ♥3-3?

[eagles123]

I would've thought Ace diamond better but just a gut feeling

[wanoff]

It's better to finesse ♦J by quite a bit.
Give yourself ♥J and it's a lot closer though I think I might still finesse.

[MrAce]

Finesse is right of course

You can try to drop K and if it does not drop you can try for 3-3 hearts (assume you played a dia and LHO followed small)

Dropping K is % 13
3-3 ♥ is % 38
Combined chance are % 33 (is this true? It's been long time )

Finesse is % 37 for the relevant cards (I do not count K stiff onside)

[MrAce]

 wanoff, on 2014-November-01, 06:24, said:

It's better to finesse ♦J by quite a bit.
Give yourself ♥J and it's a lot closer though I think I might still finesse.

♥ J changes much more than you think. After K did not drop you are not only making on 3-3 hearts but any heart split as long as the last trump hand holds longer hearts.

[MrAce]

I think I overlooked the fact that in the case of 3-0 trump break, 3-3 hearts won't help. So Wanoff may as well be correct that even with ♥ J, finnesse can be right. I am sure one of our math guys/gals will tell the precise % for it.

[WesleyC]

The finesse is the better option 50% vs 45%.

The win chance playing for drop is given by:

26% (chance of singleton king)
and
52% (chance of Kx in either hand) * 36%* (chance of 3/3 hearts).

You might also get a slight extra chance if trumps are 3-0 and they don't cash the As

-----

If you also had the J♥ then your chance of playing for the singleton would also pickup 4/2 5/1 6/0 hearts with 2/1 trumps.
This swings the odd significantly

26% + 52% * 63.5% (chance of 3+ hearts with the long diamonds) = 59%

[kgr]

Thanks you all for the answers.
I didn't matter in this deal because both finesse worked & Hearts 3-3, but I was curious what was the best line.

[MrAce]

 WesleyC, on 2014-November-03, 08:30, said:

The finesse is the better option 50% vs 45%.

The win chance playing for drop is given by:

26% (chance of singleton king)
and
52% (chance of Kx in either hand) * 36%* (chance of 3/3 hearts).

You might also get a slight extra chance if trumps are 3-0 and they don't cash the As

-----

If you also had the J♥ then your chance of playing for the singleton would also pickup 4/2 5/1 6/0 hearts with 2/1 trumps.
This swings the odd significantly

26% + 52% * 63.5% (chance of 3+ hearts with the long diamonds) = 59%

Isn't it a mistake to add K stiff onside? Because we already played a dia towards dummy and saw LHO can not have a stiff K.

[WesleyC]

 MrAce, on 2014-November-03, 15:23, said:

Isn't it a mistake to add K stiff onside? Because we already played a dia towards dummy and saw LHO can not have a stiff K.

My solution essentially looked at all the possible layouts before any cards have been played at all and then worked out on how many of those layouts each strategy was going to succeed. This is usually called the 'a priori' chance. In this example Stiff King onside is included as a win for both strategies and Kxx offside is included as a loss.

You could calculate the chance of success at a different point (e.g. after LHO has followed low to the first diamond or after you dropped the Stiff King dropped offside). At this point some possibilities have been eliminated and the chance of success might be different, but when comparing a simple strategy like drop vs finesse that can't be varied, you won't get a more meaningful answer.

[nige1]

 kgr, on 2014-November-01, 05:13, said:

MP's Small ♣ lead for ♣Q and ♣A. Is it best to finesse ♦ OR play ♦A and hope for ♦K singleton or ♥3-3?

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WesleyC seems correct..

• Running ♦J works when LHO has ♦K = about 50%.
• Cashing ♦A works when ♦K is singleton or (♦K is doubleton and ♥ are 3-3) = 26% + (52% * 36%) = about 45%

[kgr]

Thank you all for the answers!

 WesleyC, on 2014-November-03, 08:30, said:

The finesse is the better option 50% vs 45%.

The win chance playing for drop is given by:

26% (chance of singleton king)
and
52% (chance of Kx in either hand) * 36%* (chance of 3/3 hearts).

You might also get a slight extra chance if trumps are 3-0 and they don't cash the As

-----

If you also had the J♥ then your chance of playing for the singleton would also pickup 4/2 5/1 6/0 hearts with 2/1 trumps.
This swings the odd significantly

26% + 52% * 63.5% (chance of 3+ hearts with the long diamonds) = 59%

After the lead the probability that LHO has ♦K will be higher than 50% because he didn't lead ♦.
Maybe even enough to still finesse ♦ if we would have J♥

[PhilKing]

 MrAce, on 2014-November-03, 15:23, said:

Isn't it a mistake to add K stiff onside? Because we already played a dia towards dummy and saw LHO can not have a stiff K.

That's partly balanced by West not showing out. The finesse is slightly odds against. And it's worst against a very weak defender, who might cover the ♦J with KTx.

[MrAce]

 PhilKing, on 2014-November-04, 04:59, said:

That's partly balanced by West not showing out. The finesse is slightly odds against. And it's worst against a very weak defender, who might cover the ♦J with KTx.

I assume you are talking about when we hold ♥J

[nige1]

PhilKing hints at another amusing wrinkle. Suppose that you are missing ♦KT9, playing 6♦ on a ♣ lead. Now the finesse is inferior...
- The finesse wins when LHO has: singleton ♦K, doubleton ♦Kx, or (♦KT9 and 3 ♥s) = 13% + 26% + (11% * 36%) = about 43%
- Cashing ♦A wins when ♦K is singleton or when (♦Kx is doubleton and ♥ are 3-3) = 26% + (52% + 36%) = about 45%.
- Even when intending to cash ♦A, you should still lead ♦J from hand, in case LHO makes the mistake of covering with ♦KT9 and 3 ♥s. If LHO would cover to preserve his trump trick, that increases your odds to about 49%.

---

[PhilKing]

 MrAce, on 2014-November-04, 05:16, said:

I assume you are talking about when we hold ♥J

I just mean that the finesse is slightly worse than 50% - I was not comparing the two lines. They are probably close enough that you need to be at the table to decide whether to try the combo play.

[lamford]

I don't know how you can conclude the diamond finesse is slightly odds against. West might have led a spade if the diamond finesse was losing; certainly if he is looking at the ace of spades he should, so I think the diamond finesse is a favourite if anything. The chances of stiff king of diamonds or hearts 3-3 and diamonds 2-1 seems to be around 43% anyway, so this one does not look close.

[MrAce]

 lamford, on 2014-November-04, 10:30, said:

I don't know how you can conclude the diamond finesse is slightly odds against. West might have led a spade if the diamond finesse was losing; certainly if he is looking at the ace of spades he should, so I think the diamond finesse is a favourite if anything. The chances of stiff king of diamonds or hearts 3-3 and diamonds 2-1 seems to be around 43% anyway, so this one does not look close.

Why do you think W knew the location of ♦ A? If anything, he would think that S is more likely to have it, thus he would have cashed spade A if he had it + ♦K, no?

[kgr]

Please let me know if below calculation is not correct:

After having played a small Diamond and West follows with D2.
KT2 - 11 11
KT 2 13
K2 T 13 13
K T2 13
T2 K 13 13
T K2 13
2 KT 13 13
- KT2 11
Only the possibilities with West having D2 are still valid.
This gives:

For playing the DA:
- East single DK: 26%
- East T singleton or KT Doubleton: 52% ; with H 3-3: 52%*36%=19%
=> 45%

For Finesse:
- West DK2: 26%
- West DKT2: 11% ; with H 3-3: 11%*36%=8%
=> 34%
What is wrong with this..or is playing DA better anyway?

[MrAce]

 kgr, on 2014-November-04, 10:50, said:

Please let me know if below calculation is not correct:

After having played a small Diamond and West follows with D2.
KT2 - 11 11
KT 2 13
K2 T 13 13
K T2 13
T2 K 13 13
T K2 13
2 KT 13 13
- KT2 11
Only the possibilities with West having D2 are still valid.
This gives:

For playing the DA:
- East single DK: 26%
- East T singleton or KT Doubleton: 52% ; with H 3-3: 52%*36%=19%
=> 45%

For Finesse:
- West DK2: 26%
- West DKT2: 11% ; with H 3-3: 11%*36%=8%
=> 34%
What is wrong with this..or is playing DA better anyway?

First of all you need to start ♦ J, not small. It won't cost anything, but As Phil said someone may cover from KTx.
2nd, E holding stiff K is not % 26, it is % 13