[lamford]

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Lead J♠ Teams

I have been using self-isolation by working my way through the Bridge Master series. Ny partner does not think it will last long enough for me to complete the task, but I shall persevere. This was one on which I disagreed with the recommended line.

How would you play? It is clear that the only potential losers are in trumps.

[Cyberyeti]

I presume they suggest crossing to a diamond and running 7♥ if E plays low, if he plays the 9 you win and hope he's 3433 if W shows out.

Embarrassing when trumps are more favourable and W had 7 spades.

[lamford]

Cyberyeti, on 2020-April-03, 05:35, said:

I presume they suggest crossing to a diamond and running 7♥ if E plays low, if he plays the 9 you win and hope he's 3433 if W shows out.

Embarrassing when trumps are more favourable and W had 7 spades.

Or seven diamonds, or six clubs … Although you can also pick up 3-4-2-4 with East with the recommended line ...

[DavidKok]

If hearts break 3-1 or better the contract is guaranteed, so you should guard yourself against a 4-0 break. If west has all 4 hearts you can prevent more than 1 loser by playing towards the T in dummy twice, provided you don't cash the ace early. If east has all the missing hearts you can play for an endgame if you guess the distribution, intending to strip east down to all hearts and throwing them in on the second round (forcing them to lead away from Q6 towards AT). For this play east needs to have a 3=4=3=3 or 3=4=2=4 shape, because you need to take 10 tricks first without east ruffing (3 spades, 1 heart, 2 diamonds, 3 clubs and one ruff in south).

You can combine these chances by crossing in diamonds and leading a small heart. If east shows out you overtake and play a heart towards north, guaranteeing the contract. If east plays the 6 you duck, and either the trick holds (west showing out) or west covers (and the hearts are 3-1 or better). If east covers you cover with the king, and again either the hearts are 3-1 or you have to go for the endplay, but with east having all hearts you never had a better option than the endplay anyway. For this last scenario you cash all your winners outside hearts, ending in dummy. At this point you have a count of the clubs so you know whether to ruff a diamond (if east has 3=4=3=3) or a club (if east has 3=4=2=4), and then you play a heart to the 8 to complete the endplay.

Edit: as a response to the claims above, when missing 7 cards in a suit (spades) they will break 6-1 about 7% of the time, so 3.5% of the time with the 6-card in west. Compared to a 1/8 chance of hearts breaking 4-0 (~12%), or 6% of finding east with all the hearts. Similarly, a 6-0 club break with clubs in west (and not leading them, I may add) is very unlikely compared to the chance of a poor heart break. Without completely checking the math, I think preparing for an unfortunate heart break is the percentage play.

[lamford]

DavidKok, on 2020-April-03, 05:52, said:

Edit: as a response to the claims above, when missing 7 cards in a suit (spades) they will break 6-1 about 7% of the time, so 3.5% of the time with the 6-card in west. Compared to a 1/8 chance of hearts breaking 4-0 (~12%), or 6% of finding east with all the hearts. Similarly, a 6-0 club break with clubs in west (and not leading them, I may add) is very unlikely compared to the chance of a poor heart break. Without completely checking the math, I think preparing for an unfortunate heart break is the percentage play.

What I think you are missing is that in addition to hearts being 0-4, which is 4.8% only, you also need East to be 3-4-2-4 or 3-4-3-3. This makes the layout that your playing for less than 1%, while the combined chance of spade 7-1, diamonds 7-1 or clubs 6-0 is around 3.6%. So preparing for an unfortunate heart break is not even in the ball park of the percentage play.

[DavidKok]

A very good point, you are completely correct. Although we do have to make even more assumptions about the distribution - for west to give east a ruff in this line, he needs exactly 1 or 2 hearts not containing the 6. Curiosity got the better of me, and I wrote a little program to figure out what the percentages that we are catering to here are.

Out of the total 10400600 possible hands the defenders can have (I'm ignoring the lead information because this does not help decide the play), there are

• 71568 hands (or 0.69%) where west can take the heart duck and give east a spade ruff
  
• 71568 hands (or 0.69%) where west can take the heart duck and give east a diamond ruff
  
• 36624 hands (or 0.35%) where west can take the heart duck and give east a club ruff
  
• 86240 hands (or 0.83%) where east has all 4 hearts and the right shape for the endplay

Even assuming that our expert opponents would have led a club for down 1 immediately if that would provide a ruff, it is still an unnecessary risk (1.38% versus 0.83%) to take the line I suggested earlier. Based on this the percentage play is to smash down the king of hearts at trick two.

[lamford]

DavidKok, on 2020-April-03, 10:08, said:

A very good point, you are completely correct. Although we do have to make even more assumptions about the distribution - for west to give east a ruff in this line, he needs exactly 1 or 2 hearts not containing the 6. Curiosity got the better of me, and I wrote a little program to figure out what the percentages that we are catering to here are.

Out of the total 10400600 possible hands the defenders can have (I'm ignoring the lead information because this does not help decide the play), there are

• 71568 hands (or 0.69%) where west can take the heart duck and give east a spade ruff
  
• 71568 hands (or 0.69%) where west can take the heart duck and give east a diamond ruff
  
• 36624 hands (or 0.35%) where west can take the heart duck and give east a club ruff
  
• 86240 hands (or 0.83%) where east has all 4 hearts and the right shape for the endplay

Even assuming that our expert opponents would have led a club for down 1 immediately if that would provide a ruff, it is still an unnecessary risk (1.38% versus 0.83%) to take the line I suggested earlier. Based on this the percentage play is to smash down the king of hearts at trick two.

Very good analysis, and I had also not discounted the hands where East does not have the six of hearts. Perhaps the best play in practice is to cross with a diamond and lead the seven of hearts but rise if East does have - and equally important does play - the six. Of course the unlucky expert runs into diamonds 8-0 ...

[nige1]

Lamford writes 'Lead J♠ Teams. I have been using self-isolation by working my way through the Bridge Master series. Ny partner does not think it will last long enough for me to complete the task, but I shall persevere. This was one on which I disagreed with the recommended line. How would you play? It is clear that the only potential losers are in trumps.
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In the light of the erudite analysis, perhaps declarer should win the lead with ♣A; and cross to dummy's ♦A; to lead ♥7; but then rise with ♥K no matter what RHO plays. In real life, it's hard to imagine that RHO will often play low, smoothly, from ♥ Q J 9 6 .

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