Drop or finesse?

[PhilMarlow]

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It's a robot individual - you and three robots. The bidding is usually 1S-1NT-4S and the opening lead is almost always the club 9. Assuming there is no ruff, the only issue is whether you lose a spade trick. To me, the percentage play is to use your only entry to take a spade finesse - 50%. Dropping the Q is odds-against.

 

Of those faced with the problem, 7 of us finessed while 26 dropped the Qx on their left. What do they know that I don't? For the record, west held Qx, AJx, 9xxxxx, 9x.

[mike777]

[hv=pc=n&s=sakjt987hdqt8ckqt&n=s6hq86432dj4ca642]133|200[/hv]

 

It's a robot individual - you and three robots. The bidding is usually 1S-1NT-4S and the opening lead is almost always the club 9. Assuming there is no ruff, the only issue is whether you lose a spade trick. To me, the percentage play is to use your only entry to take a spade finesse - 50%. Dropping the Q is odds-against.

 

Of those faced with the problem, 7 of us finessed while 26 dropped the Qx on their left. What do they know that I don't? For the record, west held Qx, AJx, 9xxxxx, 9x.

 

 

 

why assume no ruff?

[BunnyGo]

why assume no ruff?

 

What I think Mike is getting at is that if you finesse and lose, then there could easily be a diamond shift, club ruff, and this is now down. While just playing spades from the top all but guarantees the contract. Not sure what's best (I'm terrible at matchpoint decisions like this) but at IMPs for sure I would spurn the finesse, and probably at matchpoints too.

[inquiry]

First, the spade finesse is not 50% to avoid a spade loser.

 

You are missing five spades to the Queen. Even if East has the spade Queen, you will not "pick it up" if East has Qxxx or Qxxxx. So of the 50% of the time the queen is on side, you fail in 2 out of the five cases.

 

So play AK from top picks up singleton or doubleton queen either side, which admittedly has less chance of picking up the queen than crossing to dummy and finessing. If we had to work out the mathematics, finessee wins about 37% of and playing the AK only 33% of the time. Four percent is a huge advantage for your line of play. Vegas wins a lot of money on lower odds.

 

There is a couple of dangers in your line, however. West might have spade queen and singleton club, in which case a ruff might be found. Even as bad, either opponent might have a doubleton diamond and they manage a ruff there on third round. So you have to weigh the chance of an unfortunate ruff. There is another small thing to consider. IF West is short in clubs (as it seems from the lead of the club nine) and if East has AT LEAST one top heart honor and one top diamond honor (as with AK of either suit west would lead one), what implications does that give us? I think this decreases the odds EAST has the spade queen, but not enough to influence the line I would play.

 

At imps, bang AK of spades is right. At matchpoints, I think I would still win the club ACE at trick one and go with the spade hook. If it loses, West has to guess to lead a diamond and not a heart if he had a singleton club. I guess I would risk it.

[PhilMarlow]

Thanks for the thoughtful replies. Why ignore the ruff? Barry Crane's rule - no safety plays.

 

Clearly as you have enumerated, there is a case for choosing the successful line. I think there may even be a restricted choice argument that West's lead of a safe club affords a presumption that it holds the queen, otherwise it might have led a spade. Still, I was shocked by how lopsidedly the field rejected my line, which I suspect may have something to do with knowledge of gib's lead tendancies.

 

First, the spade finesse is not 50% to avoid a spade loser.

 

You are missing five spades to the Queen. Even if East has the spade Queen, you will not "pick it up" if East has Qxxx or Qxxxx. So of the 50% of the time the queen is on side, you fail in 2 out of the five cases.

 

So play AK from top picks up singleton or doubleton queen either side, which admittedly has less chance of picking up the queen than crossing to dummy and finessing. If we had to work out the mathematics, finessee wins about 37% of and playing the AK only 33% of the time. Four percent is a huge advantage for your line of play. Vegas wins a lot of money on lower odds.

 

There is a couple of dangers in your line, however. West might have spade queen and singleton club, in which case a ruff might be found. Even as bad, either opponent might have a doubleton diamond and they manage a ruff there on third round. So you have to weigh the chance of an unfortunate ruff. There is another small thing to consider. IF West is short in clubs (as it seems from the lead of the club nine) and if East has AT LEAST one top heart honor and one top diamond honor (as with AK of either suit west would lead one), what implications does that give us? I think this decreases the odds EAST has the spade queen, but not enough to influence the line I would play.

 

At imps, bang AK of spades is right. At matchpoints, I think I would still win the club ACE at trick one and go with the spade hook. If it loses, West has to guess to lead a diamond and not a heart if he had a singleton club. I guess I would risk it.

[VM1973]

I've never played with robots, so I'm going to be speculating aloud.

 

We note that the opener has led the 9 of clubs. Now I don't know what that means because I don't know what robots lead, but I'm going to guess that it might be:

 

A) Stiff

B) High from doubleton

C) Top of nothing (3 cards)

 

For those that know that robots play MUD or something, they will have different calculations.

 

If we assume that LHO has on average 2 clubs that means RHO has on average 5. The chances of the queen being onside under those circumstances are only 42.1 percent and assuming that you do win in dummy and lead a spade and LHO produces a low one then your odds of the queen being onside have dropped to 38.9 percent (as we have eliminated the possibility of stiff ♠Q with RHO). Now according to my calculations some 9.44% of the time RHO will have Qxxx and another 1.14% will have Qxxxx (but I will warn you that my calculations have been off before).

 

The upshot is that I think you should rethink the assumption that finesses are automagically 50 percent.

[matmat]

Thanks for the thoughtful replies. Why ignore the ruff? Barry Crane's rule - no safety plays.

uhm... I am not convinced this is a safety play.

[JLOGIC]

Still, I was shocked by how lopsidedly the field rejected my line, which I suspect may have something to do with knowledge of gib's lead tendancies.

 

Wayyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy too much credit to the field. The field sucks at bridge. They played AK of spades because they didn't want to go down. A lot of people think this way about bridge. It's good that it caused you to reconsider and post the hand, but that's pretty much all there is to it.

 

If the SQ is off and they have a ruff, why do you think LHO will shift to a diamond? Dummy is basically dead, he's just going to play back a trump and hope you are down. A diamond back is a dangerous play. Even a human would have a hard time playing a diamond from the ace or king if it did not play trump suit preference.

 

On that note, it is worth noting that against a human you will often gain by finessing the trump when LHO has a stiff club and the SQ, if they have queen fourth you allow RHO to discard with a signal (encouraging diamond), whereas if you just finessed RHO would not get a chance to signal. Since GIB does not signal that point is moot.