[lamford]

Q432 visible in dummy opposite 108765 in the closed hand, which is known to have five of the suit, trumps. Plenty of entries and you need to play the suit for two losers. Assuming perfect defence, but not omniscience.

[Fluffy]

you mean the opponents aren't play J from HJ9 over the 8 so we can safely duck the 9 hopng for a stiff honnor behind but cover the jack?

[Phil]

I initially read this as:

Dummy: T8765

Declarer: Q432.

and wrote:

2-2's , singleton A or K onside or AKJ9 onside do not matter.

With AJ9 or KJ9, a defender has on interesting f/c by playing the J which appears risk-free. Declarer needs to decide between J and AKJ (where its right to cover) and AJ9/KJ9 (where its right to duck).

When the defender plays the 9 on round one, we need to decide between KJ9/AJ9 and AK9 and ducking looks superior.

With:

Q432

T8765

I think its the same.

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Maybe we should transfer this over to the other falsecard thread?

[lamford]

Fluffy, on 2012-October-22, 10:40, said:

you mean the opponents aren't play J from HJ9 over the 8 so we can safely duck the 9 hopng for a stiff honnor behind but cover the jack?

There are five cases where your play matters, of the eight singletons in total. (In three of them you have three losers).
If LHO is under the Q and RHO is over the queen:
a) J opposite AK9 you need to rise
b) AKJ opposite 9 you need to rise, as LHO has to play low
c) AK9 opposite J you need to rise, as LHO has to play low
d) KJ9 opposite A, West may well try the jack, but he is more likely to have a) or b) so you rise
e) AJ9 he has to play low - as he cannot see the king - and you can duck or rise as you choose. It is symmetrical.

In practice, rising when the jack appears and ducking if the nine appears is best, as it breaks even on AJ9 and AK9, and will gain by whatever percentage the person fails to find the falsecard from KJ9. He has to find it always to make it a toss-up.