[Tramticket]

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You have arrived in a good contract. The defence start with ace and king of clubs, followed by a third club won in hand with the queen (or won in dummy with the knave if you prefer?)..

At IMPs, you take the safety play for one loser in trumps. What do you do at Match-point Pairs (mixed field)?

[Cyberyeti]

I think most people will be in game here, stiff king with West is more likely than void, but is it more likely by enough to deal with the people that don't bid game ? I judge the people sitting my way, and the systems played (if most play 5M it's a little different to where most with say 4♠4♦ open 1♠, in that the 5M people WILL be in game, even the 4M4m brigade open the minor 1♠ is 5 an awful lot of the time). If I think most play 5M I cash the ace, if most play old style Acol I think more will miss game and play small towards the 10♠.

[The_Badger]

No. No. No. Playing safe for an 11% (half of 22% 3-0 split) chance is just bonkers, in my opinion.

[nige1]

Tramticket asks "You have arrived in a good contract. The defence start with ace and king of clubs, followed by a third club won in hand with the queen (or won in dummy with the knave if you prefer?).. At IMPs, you take the safety play for one loser in trumps. What do you do at Match-point Pairs (mixed field)?"
++++++++++++++++++++++++++++++++++

IMO: Win ♣J in dummy and lead a ♠. If RHO follows, then cover his card.
As Cyberyeti points out, this safety-play loses when LHO has singleton King but he is almost equally likely to be void.
4♠ is an excellent contract and the first 3 tricks have relieved you of most of your worries.
Some pairs might under/over-bid, so It would be a pity to go down for a minus-score.

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[Tramticket]

 nige1, on 2018-November-16, 10:00, said:

Tramticket asks "You have arrived in a good contract. The defence start with ace and king of clubs, followed by a third club won in hand with the queen (or won in dummy with the knave if you prefer?).. At IMPs, you take the safety play for one loser in trumps. What do you do at Match-point Pairs (mixed field)?"
++++++++++++++++++++++++++++++++++

IMO: Win ♣J in dummy and lead a ♠. If RHO follows, then cover his card.
As Cyberyeti points out, this safety-play loses when LHO has singleton King but he is almost equally likely to be void.
4♠ is an excellent contract and the first 3 tricks have relieved most of your worries.
Some pairs might under/over-bid, so It would be a pity to go down for a minus-score.

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Yes, I think that this is where I am. The Maths is fairly easy to calculate. The contract is only in danger if East holds ♠KJ9 (11% as The Badger states) and leading to the 10* will win in this situation. Leading the ace will gain if west has the singleton king (13%). So a 2% advantage to playing the ace - not much and only worth taking as long as everyone is in 4♠.

[* At our table, declarer won trick three in hand as described in my opening post. Now the only safety play available is low to the queen. This must be worse as it loses whenever either opp has a singleton king (26%)!].

[Cyberyeti]

 Tramticket, on 2018-November-16, 10:24, said:

[* At our table, declarer won trick three in hand as described in my opening post. Now the only safety play available is low to the queen. This must be worse as it loses whenever either opp has a singleton king (26%)!].

He can think and if he wants to safety play he can cross to dummy in hearts or by ruffing a winning diamond (better)

Small to the Q is not as terrible as you think, put yourself in the W seat with KJ, be terribly embarrassing for this trick to go K small A you may yet win.

[Tramticket]

 Cyberyeti, on 2018-November-16, 10:26, said:

He can think and if he wants to safety play he can cross to dummy in hearts or by ruffing a winning diamond (better)

There's only one entry in hearts and you need two. I didn't spot the option to ruff the high diamond!

But declarer missed the safety play and I was sitting East with KJ9.

[Stephen Tu]

Imo I can't see any plausible auction no matter the system that misses game. People who are higher we still beat by playing ace. LHO with void spade, favorable, club ace king, might have acted with a red q; I think void is encouraging action more than stiff k.

So I am going down at matchpoints.

[gszes]

LHO had the club AK and an opportunity to make a switch yet continued clubs (red suit holdings making a switch look dangerous?). That means lho is highly unlikely to also hold the spade K mainly due to the fact they would rarely be dealt virtually all of the defensive values. This is not conclusive evidence BUT it does point out an interesting position. Since the spade K appears to way more likely to be with east a safety play of small toward the ten caters to this very probability. I firmly believe the inference of the spade K position more then offsets the 2% MP advantage of trying to drop the stiff K from either opp. Note that a spade toward the Q is ALSO a safety play here but one that gives up on ever finding the stiff K and a vital MP overtrick.

[Tramticket]

 Stephen Tu, on 2018-November-16, 11:02, said:

Imo I can't see any plausible auction no matter the system that misses game.

Well, your decision will make no difference compared to the two E/W pairs conceding 800 in 5D*, but one E/W got away with 500 in 5D*.

[Stephen Tu]

 gszes, on 2018-November-16, 11:46, said:

LHO had the club AK and an opportunity to make a switch yet continued clubs (red suit holdings making a switch look dangerous?). That means lho is highly unlikely to also hold the spade K mainly due to the fact they would rarely be dealt virtually all of the defensive values. This is not conclusive evidence BUT it does point out an interesting position. Since the spade K appears to way more likely to be with east

This isn't sound logic. A priori, West is unlikely to have been dealt the 3 biggest missing black honors, sure. But once he shows up with akx clubs, the odds basically go back to 50 50 on the location of the sk. Since we are now only looking at deals where lho has akx clubs. The odds would swing if lho had shown up with longer clubs than rho.

[johnu]

 Tramticket, on 2018-November-16, 10:32, said:

There's only one entry in hearts and you need two. I didn't spot the option to ruff the high diamond!

Why do you need 2 entries? You only have to make 1 low trump lead from dummy for the safety play to work.

[gszes]

 Stephen Tu, on 2018-November-16, 12:55, said:

This isn't sound logic. A priori, West is unlikely to have been dealt the 3 biggest missing black honors, sure. But once he shows up with akx clubs, the odds basically go back to 50 50 on the location of the sk. Since we are now only looking at deals where lho has akx clubs. The odds would swing if lho had shown up with longer clubs than rho.

r u sure? If lho had indeed started with !CAK !HQ !DQ and 3 clubs and 1 spade (the K) this would have given them 14 hcp and 9 red cards maybe enough for an overcall or x over the 1s bid. The number of hands lho can have with the stiff spade K are really quite limited.

[Stephen Tu]

The number of hands lho can have with void are also quite limited.

I'm mainly disputing your claim that rho is "highly likely to have sk mainly because lho unlikely to be dealt all the defensive values". Once he shows up with akx clubs we are reducing sample space to just those hands, in which case he still has king half the time. Sure unlikely to have king plus BOTH red queens, which would takeout double, but similarly void with both qs likely overcalls or Michaels or doubles also.

The critical number is how many are in contracts other than 4s that you can guarantee a positive swing against by playing safe, ignoring results out of range like the +800s. I think basically if you think 20+ percent are in these alt contracts that supports playing safe. (After 3-3 split, odds of void drop slightly, stiff k go up a tad, vs before any cards played, it's like 10.53 vs 13.16)

[wank]

of course not. you only take safely plays at matchpoints when you're in contracts you don't think other people will bid.

even at club level everyone will get to game and shouldn't go overboard.

if lho had stiff king and i hooked into it, i would expect to get a 0. there's nothing 'safe' about that.

[Povratnik]

 wank, on 2018-November-17, 03:44, said:

of course not. you only take safely plays at matchpoints when you're in contracts you don't think other people will bid.

even at club level everyone will get to game and shouldn't go overboard.

if lho had stiff king and i hooked into it, i would expect to get a 0. there's nothing 'safe' about that.

So you think the gain of making 650 (instead of 620) is bigger than the loss if you make -100 (instead of 650)?

[Cyberyeti]

 Povratnik, on 2018-November-17, 14:31, said:

So you think the gain of making 650 (instead of 620) is bigger than the loss if you make -100 (instead of 650)?

At MPs they're more or less the same, but more people will bang down the ace, as stiff K is marginally more likely than void for W, if you want to create a swing, this is a decent place to try the safety play.

[Stephen Tu]

 Povratnik, on 2018-November-17, 14:31, said:

So you think the gain of making 650 (instead of 620) is bigger than the loss if you make -100 (instead of 650)?

The gain of making the uptrick is smaller than the swing of making vs going down. But it's also more frequent. So it depends what percent are in the normal 4s vs say 5d-x down 3 or fewer.

Suppose we are playing field where 9 other tables play 4s, all playing for drop stiff k off, and one escaping for 5d successful sac. By playing safe instead of banging down ace you swing 5.5 points your way 10.53%, of the time. But you lose 4.5 mp 13.16%, which is a bigger number, so safety play is negative expectation in this case. But if only 70 percent of field was in 4s, the rest in contracts that 620 beats, safety play would then win.

[Povratnik]

 Cyberyeti, on 2018-November-17, 14:57, said:

At MPs they're more or less the same, but more people will bang down the ace, as stiff K is marginally more likely than void for W, if you want to create a swing, this is a decent place to try the safety play.

We can go even further. If a team match with matchpoints is played (where you can make only TOP, ZERO, or 50%), trying to drop the stiff king is definitely (mathematically) better than safety play. Definitely, but only slightly; so I'd ignore that. I know you'll agree (with the blue strategy), but for the sake of other readers:

If I played such a match, I'd try to make as educated guess as possible - what would my direct opponent (South from other team) do. If we have a lead in the match, I'd try to play same as him. If we're behind, I'd try to play differently than him.

But in big and heterogeneous field, I'd always chose to make the game (see below)...

 Stephen Tu, on 2018-November-17, 15:32, said:

The gain of making the uptrick is smaller than the swing of making vs going down. But it's also more frequent. So it depends what percent are in the normal 4s vs say 5d-x down 3 or fewer.

Suppose we are playing field where 9 other tables play 4s, all playing for drop stiff k off, and one escaping for 5d successful sac. By playing safe instead of banging down ace you swing 5.5 points your way 10.53%, of the time. But you lose 4.5 mp 13.16%, which is a bigger number, so safety play is negative expectation in this case. But if only 70 percent of field was in 4s, the rest in contracts that 620 hearts, safety play would then win.

You've chosen a pretty small and very homogeneous field, so I can't disagree with you (though you couldn't claim even a 0.013 points advantage for chasing an overtrick - if you didn't count the fact that clubs are 3-3).

However, I am used to pair tournaments where every board is played by 15+ pairs, some of them players of international class, some of them (nearly) beginners. In such heterogeneous field, my experience is:

If you always make 620 in boards where -100 and 650 are also possible - your net result will absolutely and definitely be (well) over 50%.

(I could elaborate why is that, but this post is already too long)

In the end, I'll just take a liberty to bring your attention to a certain direction:

In every deal, a percentage advantage (if exists) of chasing an overtrick is fixed, always the same. Points advantage of making a game (or slam) tends to grow in bigger and more heterogeneous fields...

[Winstonm]

There is just as much chance that LHO holds singleton jack as singleton king so it is a guess whether to start with the ace or to run the Q. Because I don't know what to do, I will make the safety play for my contract.