[PhilKing]

 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.

West might have led a spade if the diamond finesse were winning, with or without the ace (he is not clairvoyant).

Besides, you have taken my "conclusion" out of context, which was in reply to the post excluding stiff king onside from the equation.

[kgr]

 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?

 MrAce, on 2014-November-04, 11:05, said:

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

In my calculation I used 13% for stiff DK with RHO, but only 50% of combinations are still possible after D2 with LHO... this gives 26%; or is that completely wrong?

[PhantomSac]

I am rather embarrassed my instinct was the combo play (which is usually what I would do on a math hand irl). Proving once again that I am bad at the close math hands and that experts have too much inclination to combine chances rather than to commit. But in my defense their failure to bid probably brings the combo play up, they do have 9 spades and 11 points as well as 8 clubs and both had the chance to overcall 1S white, I think 3-0 diamonds becomes less likely than usual and stiff king becomes more likely than usual (because stiff K is generally a reason not to bid and Kx/stiff are both fine holdings for bidding, as are KTx/void obv). Maybe I am just making excuses for my failure though

Also just noticed it was MP, the diamond hook gives us a better shot at an overtrick, not that that is the priority but it counts for something in a close decision.

[MrAce]

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

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

See the bolded in quote. You show DK single with E possibility as % 26, which is not true.

[MrAce]

Kgr, we are comparing 2 lines as you asked in the OP. It is important that you start with ♦J. Once you do that, W holding

KTx
KT
Kx

%11+13+13=37 Finesse wins regardless of how hearts are split. Once it works your slam is at home.

K-Tx
Void-KTx

are irrelevant splits, they are wash.

x-KT
T-Kx
Tx-K

%13+13+13 =39. So playing the Ace would be winner by a very small margin IF it did not need 3-3 heart break. Unfortunately, it does also need 3-3 ♥ break.

[MrAce]

Deleted

[kgr]

 MrAce, on 2014-November-04, 11:29, said:

Kgr, we are comparing 2 lines as you asked in the OP. It is important that you start with ♦J. Once you do that, W holding

KTx
KT
Kx

%11+13+13=37 Finesse wins regardless of how hearts are split. Once it works your slam is at home.

K-Tx
Void-KTx

are irrelevant splits, they are wash.

x-KT
T-Kx
Tx-K

%13+13+13 =39. So playing the Ace would be winner by a very small margin IF it did not need 3-3 heart break. Unfortunately, it does also need 3-3 ♥ break.

Thank you!!
...I'm getting:
- DJ and play DA: 45%
- Run DJ: 48%

[kgr]

 PhantomSac, on 2014-November-04, 11:17, said:

I am rather embarrassed my instinct was the combo play (which is usually what I would do on a math hand irl). Proving once again that I am bad at the close math hands and that experts have too much inclination to combine chances rather than to commit. But in my defense their failure to bid probably brings the combo play up, they do have 9 spades and 11 points as well as 8 clubs and both had the chance to overcall 1S white, I think 3-0 diamonds becomes less likely than usual and stiff king becomes more likely than usual (because stiff K is generally a reason not to bid and Kx/stiff are both fine holdings for bidding, as are KTx/void obv). Maybe I am just making excuses for my failure though

LHO did lead a Club and not a Diamond, should that also be taken into account?
On another hand my teammates were in 6S with no loosers outside trump and in S: dummy: xxxx; declarer: AJxxx. A club was lead (a suit bid by declarer even). I think it is better now - because of the non-trump lead - to play SA?

 PhantomSac, on 2014-November-04, 11:17, said:

Also just noticed it was MP, the diamond hook gives us a better shot at an overtrick, not that that is the priority but it counts for something in a close decision.

The field was not good and also the 6D contract is not very good (2 aces missing). Not unexpected that we were the only pair in slam.

[lamford]

 PhilKing, on 2014-November-04, 11:16, said:

West might have led a spade if the diamond finesse were winning, with or without the ace (he is not clairvoyant).

Besides, you have taken my "conclusion" out of context, which was in reply to the post excluding stiff king onside from the equation.

West might indeed have led a spade anyway, but the hands where he has the ace of spades and a singleton trump are less likely, as he may cash the ace on the auction he had, rather than lead a horrible Jxxx clubs. When he has a singleton trump, and the opponents have bid and supported two suits, cashing the ace might beat the contract immediately or even prevent declarer cashing a putative ace and king of diamonds when partner has Qxx, then getting the spade loser away. He is not clairvoyant, but he can visual the danger of not cashing the ace of spades when he has a singleton trump.

[MrAce]

 kgr, on 2014-November-04, 11:50, said:

Thank you!!
...I'm getting:
- DJ and play DA: 45%
- Run DJ: 48%

Also there are things which can not be calculated. For example as Phil said, when you start with J how many times it will be covered by KTx. It depends on the calibre of your LHO or how tired he is.