World class down, beginer makes

[inquiry]

Here is one I kibitzed today.

 

[hv=d=s&v=n&n=sak5haq53d3cqt974&s=sqt763hk8dkq74caj]133|200|Scoring: IMP

West North East South

   -       -       -     1♠

 Pass  2♣    Pass  2♦

 Pass  2♥    Pass  2NT

 Pass  3♠    Pass  4♣!

 Pass  4♦    Dbl   4NT

 Pass  5♣    Pass  6♠

 Pass  Pass  Pass  [/hv]

 

How do you play this hand? It;s an ok slam, especially now that the diamond ACE is safely out of the way.

 

Trick one - Diamond JACK to ACE,

Trick two - Club six, ACE wins, WEST plays five

 

Ben

[skorchev]

I voted for the first variant, it looks safety. But when I see the title I guess it isn't the right play ... or I'm beginner :) .

 

 

Stefan

[inquiry]

I voted for the first variant, it looks safety. But when I see the title I guess it isn't the right play ... or I'm beginner :) .

 

 

Stefan

Hi Stephen,

 

This is a hand i watched.. i am not sure what the right line is, of course i know what worked.... I was just curious about people's thoughts.

 

Ben

[paulhar]

I like Line 1 (ruff Diamond, hope spades are 3-2) which needs only a 3-2 spade split and diamonds not 7-1 and hearts not 7-0. This is clearly superior than any line which requires a 4-3 heart split.

 

Line 2 is tempting but you lose to Line 1 on 3-2 spade splits where the third heart gets ruffed by the person with three spades, but gains on 4-1 onside spade splits where the hand with 4+ hearts holds 5+ diamonds or the CK (see below.)

 

Line (other) is just draw all the trump (need 3-2 or 4-1 onside), then play KQ of diamonds throwing clubs from dummy. Now there is four cards left, and the player with 4+ hearts needs to keep them all, so if that player had 5 diamonds or the king of clubs, the squeeze works. It also works if the defender with 4 hearts sloppily discards one or his partner pitches a diamond from 4. Still, I think this is less likely than the 3-2 split.

[luke warm]

[hv=d=s&v=n&n=sak5haq53d3cqt974&s=sqt763hk8dkq74caj]133|200|Scoring: IMP

West  North East  South

   -       -       -     1♠

 Pass  2♣    Pass  2♦

 Pass  2♥    Pass  2NT

 Pass  3♠    Pass  4♣!

 Pass  4♦    Dbl   4NT

 Pass  5♣    Pass  6♠

 Pass  Pass  Pass  [/hv]

 

Trick one - Diamond JACK to ACE,

Trick two - Club six, ACE wins, WEST plays five

seems like this is too simple, so obvious line must be wrong (after all, ben posted it and we *know* not to trust him :))

 

ruffing a diamond looks so right, eh?

[the hog]

Why is everyone in such a hurry to ruff a D? Test trumps first by playing AK. Now if they are 4-1 on side you can pick them up and play for a squeeze. If they are 3-2 you can take your D ruff and return with a H to draw the last trump.

[Cascade]

Ron I think you overlooked getting back to hand to take your diamond ruff.

 

You need two entries after the !sAK to play your line.

[jtfanclub]

Ron I think you overlooked getting back to hand to take your diamond ruff.

 

You need two entries after the !sAK to play your line.

KH, AC. AK trump, HK, ruff diamond, CA, pull trump, H to AQ to sluff a club.

 

What am I missing?

[Cascade]

Ron I think you overlooked getting back to hand to take your diamond ruff.

 

You need two entries after the !sAK to play your line.

KH, AC. AK trump, HK, ruff diamond, CA, pull trump, H to AQ to sluff a club.

 

What am I missing?

You played the AC at trick two and then cunningly played the CA at trick seven.

 

From the original post:

Trick two - Club six, ACE wins, WEST plays five

[the hog]

"Ron I think you overlooked getting back to hand to take your diamond ruff.

You need two entries after the !sAK to play your line. "

 

Whoops quite right and too early in the morning!

[jtfanclub]

Ron I think you overlooked getting back to hand to take your diamond ruff.

 

You need two entries after the !sAK to play your line.

KH, AC. AK trump, HK, ruff diamond, CA, pull trump, H to AQ to sluff a club.

 

What am I missing?

You played the AC at trick two and then cunningly played the CA at trick seven.

 

From the original post:

Trick two - Club six, ACE wins, WEST plays five

I missed it. Sorry, you're right.

[Fluffy]

Since Ben loves to squeeze I´ll try ♠AK, if it is 3-2 I am not gonna ruff a ♦, just try directly the ♥/any squeeze, I think it works 50% with ♣K, and around 30% with ♦, needing ♠3-2 or 4-1 onside it is about 55% total or so :), quite poor compared to ♠3-2 :P

[luke warm]

Since Ben loves to squeeze I´ll try ♠AK, if it is 3-2 I am not gonna ruff a ♦, just try directly the ♥/any squeeze, I think it works 50% with ♣K, and around 30% with ♦, needing ♠3-2 or 4-1 onside it is about 55% total or so :), quite poor compared to ♠3-2 :P

yes, exactly why i almost (in fact originally did) wrote to play A,K of spades, because of a possible squeeze... but i was letting my knowledge of his preferences influence me :)

 

i think ruffing the diamond is the long-run percentage play

[nige1]

I reckon immediately ruffing a diamond is the best in theory. My guess is that a sleeply declarer started on Ron's line. CA SAK. Oops! RHO has Jxxx. So HKQA discarding a club, C ruff, DKQ, Druff, and poor RHO with an original 4342 shape, resigned.

[inquiry]

Ok, thanks for playing.

 

The votes here are very reasonable. Ruff works as long as EAST didn’t have a singleton diamond ACE and SPADE split 3-2, or four one with singleton spade JACK. Lets assume given the 4♦X that East has more than one diamond. So the odds of this line is the odds of the 3-2 spade split (or 4-1 with singleton jack). The 3-2 split has odds of 67.8%, and rise to 73.5% if you include the chances for the singleton JACK in either hand.

 

Of course, the world class player (self assessment) but with a gold star took the line of ruffing a diamond in dummy at trick three. The player with “beginner” title (self assessment) did what beginners do, he pulled trumps starting with SPADE-AK, West showed out on second round, so the beginner found the spade hook, and then pulled the last trump.

 

West, who had CLUB-KING, four hearts, and six diamonds was three suit squeezed when the trump queen was chased, and naturally enough threw off all his diamond guard. South cashed his two diamonds, but as beginners do, he didn’t count to know that his diamond X was good. He then ran the hearts and threw away the club king. Ruff a club, and was surprised when his diamond 7 was good.

 

Ok, so we know that the world class expert line was 73.5%. How did our beginner do? Cashing the spade AK caters to one distribution -- EAST has Jxxx of trumps. Odds of that are only 11% (don’t count WEST having Jxxx because you can’t pick that up). Even after picking up four spades to the jack, you have to manage the squeeze ending successfully (only one opponent can have club King, only one can stop hearts, and there is a diamond threat but can’t be a both threat due to no entry in the suit, but if one of them have five or more diamonds). So the world class line seems hugely larger in his favor. But then after cashing spade AK, you are not down if spades split 3-2, not yet at least. You can now play Heart to King, diamond ruff, and cash two hearts for a club discard. So how does this affect the odds?

 

Well if hearts are 4-3 (63.8% if spades are proven to be 3-2) the beginner will be back in the ball game (at least close to the pro’s 73.5%). But even when hearts are 5-2, the beginner is not down, not yet. If the hand with five hearts has the three spades, the third heart will stand up. When hearts are 5-2, and spades are known to be 3-2, the beginner will still make.

 

So can we compare the lines? The beginner had 11% chance the pro didn’t have (4-1 split onside). If spades are 3-2, the beginner falls back on 4-3 heart split (ok, 89% x 63.8 = 56.8) so the beginner’s odds are up to 67.9%. Not as good as 73.5, but closer. Then you have to add in the odds of making when hearts are 5-2 but the player with five hearts has the third trump. Ok, since at this point, we know that spades are 3-2, if hearts are 5-2, the doubleton spade will be along with the doubleton heart 40% of the time. So what are the odds of a 5-2 heart split? That is 30% of the time, here we go again, 30% time 40% or 12%. Note this 12% does not include the 4-1 spade split, but does exclude the 4-3 heart split… so you multiply by 12% times the 4-1 spade opportunity (so 89% x 12% = 10.7%). So our beginner’s line has creeped up 67.9 + 10.7 = 78.6%.

 

So in summary, the pro’s line works 73.5% of the time with no chance for recovery.

The beginner’s line picks up the four-one trump split on sides, and when spades are 3-2, he has to rely on 4-3 hearts or 5-2 hearts with the hand with two heart having the two spades. We know (or think we know) why the beginner choose his line, but maybe, just maybe he knew more than we think he did.

 

And we thought bridge was an easy game.

 

Ben

[Free]

Easy double or triple squeeze imo, just cash ♠s and let it roll home... Opps already rectified the count :)

[Stephen Tu]

I've got some major issues with this math here.

So can we compare the lines? The beginner had 11% chance the pro didn’t have (4-1 split onside). If spades are 3-2, the beginner falls back on 4-3 heart split (ok, 89% x 63.8 = 56.8) so the beginner’s odds are up to 67.9%. Not as good as 73.5, but closer.

 

Where do you get this 89%? Spades split 3-2 only a bit less than 68% of the time. You can't count the 5-0 cases. Nor can you count 100% of the Jxxx onside cases since the squeeze won't operate in all of the cases. Nor can you count all of the other 4-1 split cases as you are doing above.

 

The SAK line works if spades (3-2 & hearts 4-3) (~42%) + (if hearts

5-2 or 6-1 with the long trump holding long hearts) + (Jxxx onside & squeeze works) + (J stiff & hearts behave). I'll ignore 7-0 hearts since bidding/defense likely different.

 

So what are the odds of a 5-2 heart split? That is 30% of the time, here we go again, 30% time 40% or 12%. Note this 12% does not include the 4-1 spade split, but does exclude the 4-3 heart split… so you multiply by 12% times the 4-1 spade opportunity (so 89% x 12% = 10.7%). So our beginner’s line has creeped up 67.9 + 10.7 = 78.6%

 

Again with the 89%. 5-2 heart split with spades 3-2 and long heart with long spade is only 8%. So up to 50% now. 6-1 hearts with friendly spades only adds about another 1%. Stiff jack of spades with long hearts with long spades is less than half a percent. So this line is only about 51.5% + the fraction of the SJxxx onside case where the squeeze operates. Clearly less than just ruffing the diamond immediately.

[EricK]

I haven't looked at the maths in Ben's post so I won't comment on that. But I will say that when I first saw the problem I assumed that immediately ruffing the diamond was the beginner's play (it seems so obvious), and drawing trumps (with a gain in certain squeeze endings, but a loss in other, simpler, positions) was the expert's play.

 

Eric

[twcho]

I conclude here with the possibility calculation with the help from a computer. :blink:

 

Ben's expert line: work on all S32 break and singleton SJ. The chance is 67.8%+5.7%=73.5% minus some chance of being ruffed in H or overruffed in D, the possibility shd be around 73%

 

Ben's beginner line: work on when S32 with longer trump holder holding at least 3H, the possibility is 67.8%*77.9%=52.8%. It also works when E has Jxxx in S and squeeze works (complicated calculation for the squeeze work, but the result is 58.4%, never computable at the table). so it addes 11.3%*58.4%=6.6%. It may also work when trump J is singleton, then you have two lines: either draw all trumps and hope for squeeze or you hope for the one holding 4 trumps also holds at least 3H and 2D and you know how to get back to hand by ruffing C or H. squeeze is the same as above, 58.4% while the latter line is 62.1% (also not computable at the table). So you shd try to ruff the D loser rather than play for squeeze in this case and the chance is 5.7%*62.1%=3.5% and the total chance for this line to work is 52.8%+6.6%+3.5%=62.9%. This line still not too bad but is about 10% worse than the immediate ruff D line.