[pescetom]

Paulg and others concerned that GiB may be better in attack than the average human might do well to look at this example.
What was GiB thinking at tricks 3 and 4 here ?

[smerriman]

You need to get in the habit of saying what you think the mistake was so I don't have to keep asking

Swap the spade holdings and you need to finesse this way - are you saying West is more likely to have the spade queen than East? If so, why? (You may or may not be right, but I'm not sure what I'm looking for yet..)

[pescetom]

 smerriman, on 2024-September-21, 15:21, said:

You need to get in the habit of saying what you think the mistake was so I don't have to keep asking

Swap the spade holdings and you need to finesse this way - are you saying West is more likely to have the spade queen than East? If so, why? (You may or may not be right, but I'm not sure what I'm looking for yet..)

I prefer to let people evaluate the situation for themselves without being distracted by my (often limited, eccentric or emotional - nobody likes a gratuitous 10%) vision of things.

I would not expect the spades holdings to be swapped after that lead and his partner's continuation. Nor apparently did the others (all declarers except my partner were humans) who received the same lead, all of them hooked spades Jack (some of them having flown hearts Queen too, be that as it may). And when it came to tackling diamonds, they hooked the Queen.
Of course a few others received diamonds or even spades lead to help them out.

[smerriman]

OK. Seems close to a 50/50 guess to me so I don't see any evidence in this hand that lines up with your message to paulg and others.

[pescetom]

A single 50/50 wrong guess rarely leads to 10% of MP in my experience.
And it's equally rare that all other declarers make the same choice if it is really 50/50 and the choice has no other consequences.

[smerriman]

I highly doubt most of your human declarers went through a lengthy analysis to decide which opponent was more likely to hold the queen and picked between the two lines accordingly. More likely, they are "programmed" to 'see finesse, take finesse' and didn't even notice the other way was a possibility. So no, it isn't unusual that even in a true 50/50 guess all humans may make the same guess.

The fact the robot doesn't have these human tendencies built in, if anything, strengthens the original argument to me. Obviously, it makes terrible mistakes, but so do humans; they just look different.

[pescetom]

 smerriman, on 2024-September-22, 13:33, said:

I highly doubt most of your human declarers went through a lengthy analysis to decide which opponent was more likely to hold the queen and picked between the two lines accordingly. More likely, they are "programmed" to 'see finesse, take finesse' and didn't even notice the other way was a possibility. So no, it isn't unusual that even in a true 50/50 guess all humans may make the same guess.

The fact the robot doesn't have these human tendencies built in, if anything, strengthens the original argument to me. Obviously, it makes terrible mistakes, but so do humans; they just look different.

To some extent I agree: a good number of them probably only decided to play for the Q in West because they saw the KJ tenace in North and thought no further than that. But the better players will have other reasons, the slight vacant places advantage and the possibility to play comfortably for ♦Q even if the finesse fails. It was also arguably mistaken not to play for ♦Q at trick 4 anyway, and indeed it would have limited the damage to -1 for 40%.

[smerriman]

Out of interest, can you spell out the vacant places argument and why you thought East was unlikely to have spades given the first two tricks? Want to run some simulations. I thought you weren't meant to use vacant places in cases like this (relating to leading your longest suit).

[steve2005]

From the lead it looks like east has 4 hearts and west 3 hearts.
So, I suppose the odds are 9-8 in favour of finessing west for Q♠.
The trouble on this auction East could easily have 3 hearts to lead an unbid suit..

[smerriman]

steve2005, on 2024-September-22, 21:19, said:

From the lead it looks like east has 4 hearts and west 3 hearts.
So, I suppose the odds are 9-8 in favour of finessing west for Q♠.
The trouble on this auction East could easily have 3 hearts to lead an unbid suit..

As an aside, from West's carding (9 then 6), it actually looks like East must have 3

But I'm sure I've read that that is a fallacious use of vacant places even ignoring this.. *whatever* they lead, you could argue that means it's less likely they hold spades.. which can't be true because they have to lead something and before that the chance was 50%.

[pescetom]

 smerriman, on 2024-September-22, 21:36, said:

But I'm sure I've read that that is a fallacious use of vacant places even ignoring this.. *whatever* they lead, you could argue that means it's less likely they hold spades.. which can't be true because they have to lead something and before that the chance was 50%.

Probability is not my strong point, but your argument smells fallacious to me... if they lead the spades Q the probability collapses to 0% but if they lead one of the other 25 cards the probability remains stubbornly 50%?
Be that as it may, the premise is different, in that a low spot card in an unbid suit is pretty much certain 4th below honour to these players. So we have a minimum 4-3 split of hearts (could have been 5-2 if the visible spot cards were different) and thus 9-10 split of spaces.
Marginal, but in absence of other indicators significant I would think.

[smerriman]

What would they lead with 3 cards in the unbid suits? Surely not 4th best in spades or diamonds on this auction?! If they do then I agree it's less likely they have spades (more because they might have led that instead, rather than based on vacant places).

But if they're always leading their longest unbid suit as I would have expected, then I'm struggling to see how doing what they were always going to do can have an impact on whether they hold another card, thus the reason I was asking you to spell out the vacant places argument (which may well be right, I'm just not sure what it is yet). Still looking for the article; maybe it was just a forum post I read once, and maybe I misread it..

Edit: ahha, maybe this was it: https://sites.google...monty-hall-trap . So it was less about who was more likely to have the missing card (which was still East), and more that vacant places was giving the wrong info for drop vs finesse. But either way, you can't use vacant places directly, but have to include implied information about other suits they may have led.

[pescetom]

 smerriman, on 2024-September-25, 15:33, said:

What would they lead with 3 cards in the unbid suits? Surely not 4th best in spades or diamonds on this auction?! If they do then I agree it's less likely they have spades (more because they might have led that instead, rather than based on vacant places).

With 3 cards in the unbid suits I would reason that Clubs or hearts are probably a gift, either ♦J or spades.
Hard to say that all others would see it the same way.