[shyams]

IMPs, all red, you bid to 6♥ with opponents passing all through.

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Opening lead was ♣9 to dummy's ♣10, East's ♣J and declarer wins with ♣A.

What is the most suitable line? This came up against robots on BBO and I found a way to go down!

[Cyberyeti]

What do robots lead 9s from ? If as I suspect this is a doubleton or singleton, the odds are significantly on W having Q♥ and he may well have 4.

You say opps passed throughout, where was the auction when E got to bid (he appears to hold ♣KQJxxx(x))

My first thought is K♥, heart finesse, ♠AQ, heart to the A, club pitch on K♠ and hope the hearts either split or the diamonds broke or W was 4-6 in the minors.

[nige1]

shyams 'IMPs, all red, you bid to 6♥ with opponents passing all through. Opening lead was ♣9 to dummy's ♣10, East's ♣J and declarer wins with ♣A. What is the most suitable line? This came up against robots on BBO and I found a way to go down!'
++++++++++++++++++

Unimaginative: Win ♣A. Cash ♥AK. Unless ♥Q drops, cash ♠AQ, ♦Q, ♠K discarding ♣.

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[Cyberyeti]

nige1, on 2020-January-02, 13:53, said:

shyams 'IMPs, all red, you bid to 6♥ with opponents passing all through. Opening lead was ♣9 to dummy's ♣10, East's ♣J and declarer wins with ♣A. What is the most suitable line? This came up against robots on BBO and I found a way to go down!'
++++++++++++++++++

Unimaginative: Win ♣A. Cash ♥AK. Unless ♥Q drops, cash ♠AQ, ♦Q, ♠K discarding ♣.

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This is the other line to mine, I'm not sure if it's better, you win when E has ♥Qx or (Qxx and the diamonds are 3-2), I win any time W has 4 hearts to the Q and the diamonds split or E has 4, and whenever W has ♥Qxx and the diamonds don't split. Not sure how the odds pan out if you assume E has 6-7 clubs opposite 1-2.

[mikeh]

Win in hand, unblock the spades, cross to the heart A, pitch the club on the spade K. Back to hand with a diamond, and low heart towards the jack.

It is unlikely anyone is void in diamonds, or has a stiff in spades. If someone ruffs the third spade, I will play for the trump Queen to drop. This won't work if east has ruffed the spade and had 7 clubs, and west can overruff the 9.

The remaining losing cases, other than unexpected pointed suit splits, are east holding Qx in trump and 7 clubs or holding Qx in trump and 4 diamonds (however, if he has this, then he has almost surely ruffed a spade already) or West holding Qx in trump and 4 diamonds and giving partner a ruff.

None of those holdings seem to me to outweigh the chance of a 4-1 trump break, now that clubs appear to be 2=6 or 1=7. As for 3-2 hearts, I am safe if west has the Q, as he rates to do, and when east has Qx, my line still makes most of the time, whereas playing an early heart finesse, before pitching the club, will always fail on that holding.

[Cyberyeti]

mikeh, on 2020-January-02, 15:07, said:

Win in hand, unblock the spades, cross to the heart A, pitch the club on the spade K. Back to hand with a diamond, and low heart towards the jack.

It is unlikely anyone is void in diamonds, or has a stiff in spades. If someone ruffs the third spade, I will play for the trump Queen to drop. This won't work if east has ruffed the spade and had 7 clubs, and west can overruff the 9.

The remaining losing cases, other than unexpected pointed suit splits, are east holding Qx in trump and 7 clubs or holding Qx in trump and 4 diamonds (however, if he has this, then he has almost surely ruffed a spade already) or West holding Qx in trump and 4 diamonds and giving partner a ruff.

None of those holdings seem to me to outweigh the chance of a 4-1 trump break, now that clubs appear to be 2=6 or 1=7. As for 3-2 hearts, I am safe if west has the Q, as he rates to do, and when east has Qx, my line still makes most of the time, whereas playing an early heart finesse, before pitching the club, will always fail on that holding.

How are you returning to hand to draw the last trump if W has 4 trumps and flies the Q, then plays a diamond ?

[mikeh]

Ruff a club. Yes, I’m down if west had a stiff club and the heart Q10xx

Tho if he is 4=3 reds I can come back in diamonds, having won his switch in dummy. And I may well be able to read the position

[Cyberyeti]

mikeh, on 2020-January-02, 16:21, said:

Ruff a club. Yes, I’m down if west had a stiff club and the heart Q10xx

Tho if he is 4=3 reds I can come back in diamonds, having won his switch in dummy. And I may well be able to read the position

I never play robots, I don't know how often it would lead 9x here

Also if Qx offside, really quite likely to get a trump lead from xxx at least from a human

[mikeh]

Cyberyeti, on 2020-January-02, 16:27, said:

I never play robots, I don't know how often it would lead 9x here

Also if Qx offside, really quite likely to get a trump lead from xxx at least from a human

Depends on the auction. If they seem to be stretching, then a trump lead is often passive and safe. If they have a strong auction to slam, and your hand suggests neither you nor partner have any unpleasant surprises for them it is often best to be aggressive. In any event, other than the common ‘lead a trump against a grand’, I don’t have any pre-determined lead ‘rules’ against high-level contracts.

As for robots, I don’t play against them either (whatever their game is, it isn’t bridge), but it occurred to me to wonder if they ever lead top from xxx. I assumed not, for my answers, but such would significantly change the inferences to be drawn.

[Cyberyeti]

mikeh, on 2020-January-02, 16:59, said:

Depends on the auction. If they seem to be stretching, then a trump lead is often passive and safe. If they have a strong auction to slam, and your hand suggests neither you nor partner have any unpleasant surprises for them it is often best to be aggressive. In any event, other than the common ‘lead a trump against a grand’, I don’t have any pre-determined lead ‘rules’ against high-level contracts.

As for robots, I don’t play against them either (whatever their game is, it isn’t bridge), but it occurred to me to wonder if they ever lead top from xxx. I assumed not, for my answers, but such would significantly change the inferences to be drawn.

I agree with this, but it does look like they might be stretching, flattish 20 vs pancake flat 10. I also asked above and when I got no answer assumed it was from 1 or 2. I think a singleton club gets led anyway, but xxx trumps might be led ahead of ♣9x

[nige1]

mikeh, on 2020-January-02, 16:59, said:

As for robots, I don't play against them either (whatever their game is, it isn't bridge), but it occurred to me to wonder if they ever lead top from xxx. I assumed not, for my answers, but such would significantly change the inferences to be drawn.

I like MikeH's line. However, disagree about robots.
Given basic game-rules (without opening/ending books, or other human input) and a few days of self-play, neural-net AI programs have taught themselves more Go, Chess, and Shogi skills, than human players have learnt in millennia of play and study.
Robots already play Bridge well ...

[mikeh]

nige1, on 2020-January-02, 17:33, said:

I like MikeH's line. However, disagree about robots.
Given basic game-rules (without opening/ending books, or other human input) and a few days of self-play, neural-net AI programs have taught themselves more Go, Chess, and Shogi skills, than human players have learnt in millennia of play and study.
Robots already play Bridge well ...

Robots declare very well, as best as I can tell. They can’t read players, but reading the opps diminishes in importance the better the player. Most top players give very little away.

However, they can’t bid worth a damn and, worse, the algorithms they follow can I gather, be effectively gamed by those willing to put in the time to study how they function. Whatever: try having a discussion with a robot about how to bid a hand, lol.

[dsLawsd]

mikeh, on 2020-January-02, 15:07, said:

Win in hand, unblock the spades, cross to the heart A, pitch the club on the spade K. Back to hand with a diamond, and low heart towards the jack.

It is unlikely anyone is void in diamonds, or has a stiff in spades. If someone ruffs the third spade, I will play for the trump Queen to drop. This won't work if east has ruffed the spade and had 7 clubs, and west can overruff the 9.

The remaining losing cases, other than unexpected pointed suit splits, are east holding Qx in trump and 7 clubs or holding Qx in trump and 4 diamonds (however, if he has this, then he has almost surely ruffed a spade already) or West holding Qx in trump and 4 diamonds and giving partner a ruff.

None of those holdings seem to me to outweigh the chance of a 4-1 trump break, now that clubs appear to be 2=6 or 1=7. As for 3-2 hearts, I am safe if west has the Q, as he rates to do, and when east has Qx, my line still makes most of the time, whereas playing an early heart finesse, before pitching the club, will always fail on that holding.

I totally agree with your analysis and line of play.

[miamijd]

nige1, on 2020-January-02, 17:33, said:

I like MikeH's line. However, disagree about robots.
Given basic game-rules (without opening/ending books, or other human input) and a few days of self-play, neural-net AI programs have taught themselves more Go, Chess, and Shogi skills, than human players have learnt in millennia of play and study.
Robots already play Bridge well ...

They do? What robots are you talking about? Certainly not the GIB bots, who are mediocre declarers, poor defenders, and downright AWFUL bidders.

[pescetom]

miamijd, on 2020-January-03, 11:04, said:

They do? What robots are you talking about? Certainly not the GIB bots, who are mediocre declarers, poor defenders, and downright AWFUL bidders.

Does the name AlphaZero say anything to you?
It cheerfully beats the best simulation bots in other mind games and would probably do so at bridge as well.
And the better bridge simulation bots such as Jack or Wbridge5 already do very well against most humans.
Even GIB is far from being a mediocre declarer.

[pigpenz]

one could also shed club on spade then play J ♥ hoping to smother 10 ♥, since we had to plaly A♥to get to dummy

[mikeh]

pigpenz, on 2020-January-03, 14:46, said:

one could also shed club on spade then play J ♥ hoping to smother 10 ♥, since we had to plaly A♥to get to dummy

The point of the hand is to cater to a bad trump break. If trump are 3-2, we almost surely can’t fail by playing AK of trump, after unlocking and taking the pitch. There is no gain from playing anti-percentage: Qx in either hand is twice as likely as 10x in lho’s hand. And of course, given that east appears to have long clubs, the odds of a 4-1 trump break, with Lho holding the length, are significant

[msjennifer]

Sir,I shall take the same line of safety play in trumps after discarding the club x on the spade winner having unblocked the spades earlier as has been described by Mikeh.