Is deep finesse defense perfect ?

[mangurian]

Does anyone know if Deep Finesse plays the best possible defense?

 

That is, does it always set the contract if there is a line of play that ensure a set?

 

Thanks

[manudude03]

Deep finesse plays and defends the hand double dummy. If declarer never falls for falsecards or other shenanigans, then yes, it is perfect so to speak.

[Cthulhu D]

Yes, Deep Finesse will always set the contract if there is a line of play that ensures a set.

 

It's almost impossible to find the same line of play at the table sometimes, which is a limitation. You'll often see in club games that the limit of the hand was 9 tricks in hearts but everyone bid and made the heart game because the lead - and it's usually the lead - is impossible to find.

[Free]

Deep Finesse looks at all the cards and always makes the best possible play for each player. It will never fail a 2-way finesse (AJT vs K98 for example) because DF knows who holds the Q.

 

If one card deviates from the suggested line of play, then the result can only improve for your opponents.

 

So the answer is YES to both your questions. If there is a way to defeat a contract, DF will find it. If there is no way to defeat a contract, then DF will find declarer's line of play to bring the contract home.

[Fluffy]

uh? I though there was a hand a couple years ago where Deep finese was proved wrong, his tree cut algorith failed to see a variation that led to give a wrong answer. 1 in millions of hands, but still exists.

[Cthulhu D]

uh? I though there was a hand a couple years ago where Deep finese was proved wrong, his tree cut algorith failed to see a variation that led to give a wrong answer. 1 in millions of hands, but still exists.

 

And lo, in the intervening years the programmer fixed the bugs.

 

I think that was the conclusion reached anyway.

[PeterGill]

The inventor of Deep Finesse Bill Bailey explains on pages 3 and 4 of

 

http://www.eurobridge.org/bulletin/09_1%20Sanremo/pdf/Bul_03.pdf

 

with an actual hand that Deep Finesse got wrong (at that time) being on pages 12-13 of

 

http://www.eurobridge.org/bulletin/09_1%20Sanremo/pdf/Bul_03.pdf.

 

So the answer for the original poster is surely, in 2013: "Nobody knows".

 

Peter.