smerriman

smerriman 55 - 3 sep123 https://webutil.bridgebase.com/v2/tview.php?t=ARDCHALLENGE:b08ae4da.2bfa.11eb.94ca.0cc47a39aeb4-1605964126&u=smerriman&v3b=web&v3v=5.6.14

While a 3♣ rebid is clear with a human partner, the danger with GIB is that over a 3NT response, you have 0 ways to continue a slam investigation other than leaping to slam. So I sympathise with the 4NT bid. However, in reality, even if it didn't promise 3 diamonds, you would get a 5♥ response and be in exactly the same final contract.

If you're just asking about how undo works on BBO: - you can ask for an undo at any time, including after subsequent actions - if your partner asks for an undo, you do see that they're asking for an undo - nobody can bid until the undo request is dealt with - as soon as one person hits reject, the undo is rejected. You can't tell which player rejected. - if the person asking for the undo cancels the request, the undo is rejected; you can't distinguish this from the above

The issue here is that the description of 4NT promises 3 diamonds. Thus with a 10 card fit, GIB's response is correct, as per at least a couple of earlier threads of yours. So it's the definition of 4NT that needs correcting, since it makes no sense for that to promise 3 diamonds.

Well, clearly there's no reason not to duck the first two hearts. While there are ways to put East on lead, they might have 4 hearts and I'd look pretty silly when I had 9 top tricks. So I'll try two top tricks in each black suit. Assuming both follow, I'll play the third top trick in each black suit. If I don't have 9 tricks yet, I'll play my last card in whichever 4 card black suit East holds, and hope they have 3 hearts and have to lead away from a diamond honor (and that I guess which it is). Maybe there's something better.

Those three are good to go now - one pool is slightly larger, but will allow players in that pool to take slightly longer to complete the first half if necessary - it'll all average out by the end.

Have asked barmar to add those three to the list of entrants and will keep you posted - hopefully everyone is OK with a slightly longer event (will adjust the deadline).

With a balanced 17-18 with stopper(s) in spades, I would know where I want to be - I would likely have bid 2NT, just as if the opponents were silent and partner had responded 1♥. But generally yes, a cue bid would just show a generic game forcing hand, and can be a multitude of different hand types; it says nothing about hearts.

Maybe, but a *lot* of people think that pass in any situation denies values (I had an opening hand - I had to bid something!), so I wouldn't be so sure.

Bidding 1NT says "I do not have 4 spades". Therefore your next bid cannot mean "actually, I do have 4 spades". It is 100% impossible (not unlikely, or improbable) that it shows spades. Thus the perfect name for the convention. Instead, the bid shows something completely different - in this case, a maximum hand with good club support. If you struggle with memory there's no need to include it in your partnership. But if you don't struggle with memory, there is 0 reason not to start using it, given it is so useful to separate good + bad club raises for the reasons Stephen Tu mentioned. Honestly, it's actually one of the easiest conventions to remember, at least from opener's point of view; as soon as you hear it you know instantly it can't possibly be natural - if you held 4 spades as opener, you were disappointed to hear 1NT and discover there was no spade fit, so hearing it immediately 'shocks' you - so what else could it mean?

Do you have any examples of where they're used inappropriately? For example, tournaments provide the double dummy 'par' scores in a printout, but I don't know of anyone who interprets them as 'this is what you should have made'; they're well known to be courtesy only. Like I said, you're meant to analyse them yourself - if you see that double dummy required dropping a singleton king, then you adjust. If people you know do use them like that, then the problem is their interpretation - not the fact they're provided. There simply isn't anything else that can be easily provided.

It's not meant to be used as showing what the correct result is. You're meant to use it as a starting point along with human analysis and adjustments. Single dummy analysis is simply too computationally difficult (if it wasn't, GIB would be unbeatable), so it's all you have.

https://www.dropbox.com/s/8w1ijcs3q9wt2mn/Event%2021.xlsx?dl=0 We have 18 entries this time, so like Event 19, this event will consist of a full round robin, with the top 4 making the semifinals. For scheduling purposes, I've divided everyone into two groups, colored blue and red. Please complete all 8 challenges within your group first. Each challenge should be a 16 board, IMP, best-hand friend challenge. Once you have completed those 8 challenges, you can begin the second half, but may only challenge others who have also completed their initial 8 challenges. The deadline for completing your first 8 challenges is December 2, 11:59pm EST. As always: If a challenge hasn't been accepted in a day or two, cancel and reissue it to make sure you don't time out after the other player accepts. Please only accept a challenge if you are positive you will be able to complete it in time. Partially completed challenges are annoying for everyone. (At least) one player should report the scores of each challenge here by pasting a results URL. You can get the URL via the History tab, clicking Results, then the icon at the top right to open the results in a new window.

There isn't really any way to define a 'good score' in either of those two formats. Since they're both scored as total points, it's fully luck dependent based on what you are dealt, rather than any skill being involved. Obviously, if you want to get on the leaderboard in Bridge 4, you're going to need to fluke game and slam hands on all 4 boards. You could play perfect bridge and still end up with a negative score. If you want a scale of how 'good' you're scoring, you should really be playing some of the IMP / MP formats instead. While they also have their flaws, at least you can compare how you played with how others played the same hands.

Alright - there aren't any examples in there of someone who led a trump at trick 2 and took less tricks, so it must have simply come down to the straightforward explanation of leading a minor after all.

Well, you also said most people made the same trump lead at trick 2, then changed that to most leading a minor, so one of those two was likely to be wrong :) Would still be interested to see one of the lines that gave away an extra trick even after leading the trump though. Do you have the traveller link?

Well, if most people bid differently to you, then GIB will regularly take a different line, so it's quite possible the difference *was* due to your 2♦ bid (even if that bid should be completely irrelevant; you know how weird GIB is in this area). But it's hard to know why other tables were different without seeing what other tables actually did. If "most" tables made exactly the same first two leads against 4♠, then 91% should be impossible, but the reason should be straightforward if you can show one of those tables that got a different result after that start. Perhaps against those who doubled, East did play for the squeeze. After ruffing out the hearts, it ran trumps, and South came down to the ace of diamonds and J8 of clubs. East then leads a low club, and South mistakenly plays the jack to 'force out the ace', throwing away the club trick. But it seems that a significant enough chunk of players would lead a club or diamond at trick 2 as others have mentioned.

For the first hand, it does look very likely partner's clubs aren't that long so they are likely to be somewhat balanced. In hearts they could have xxx, or Qx, or Kx, or Ax, or even xx with LHO having a singleton honor. In all of those cases we want to be in 3N and the only way we'll find it is if I bid it now. So I'll grit my teeth and do it without a stopper. In the second hand, I'm really not sure. Partner is likely to have club shortness, but any slam comes down to whether they have the ace of diamonds or not, along with the AQ of spades.. perhaps there's a theme here, and I'll gamble on that club singleton and go with 4NT, planning to raise a 5♠ response to 6.

Yes and no. If you want to look at absolute errors, consider the following: The 5-5-2-1 figure of 3.1739% gives sqrt(p(1-p)) = 0.1697. The 10-3-0-0 figure of 0.00015% gives sqrt(p(1-p)) = 0.0012. So the SD for the second figure is about 1/140th the size of the first. But the first figure would need an absolute error of 5e-5 to give a different rounded result, while the second figure would need an error of 5e-6 to give a different rounded result. So you need an absolute error of a tenth the size - but with 1/140th the standard deviation. So while you are interested in the absolute error, the fact it is smaller for smaller numbers isn't important - it's only about how that compares to how much you're scaling down the required accuracy. If you measured both to the same number of significant figures, the smaller values would be more volatile. If you measured both to the same number of decimal places (so it's solely about absolute error), the smaller values would be more accurate - but they're clearly not doing that in the table.

Actually, the opposite of what you're implying :) While sqrt(p(1-p)) gets smaller as p gets smaller, it gets larger in proportion to p - for example, when p is 0.1, you get 0.3 (three times p), while when p is 0.00001, you get 0.003: 300 times p. So you would expect greater deviation in the results for smaller p - it's the fact this is completely overwhelmed by the rounding in the table that the numbers match so well.

The reason it's not as surprising as it first seems is due to the choice of the number of significant figures to display. For example, to 2sf, the theoretical 12-1-0-0 split is 0.00000032%, while the table would give 0.00000029%. Restricting it to 1sf means it would match the theoretical figure if there were anywhere between 143 and 199 occurrences of that distribution, which is a gigantic margin of error. Likewise, if the 10-3-0-0 shape was measured to 3sf, there would be a slight deviation in the table (0.000154 vs 0.000155) - 2sf would work for anywhere between 82501 and 88190 occurrences, which is inevitable.

How does Muppet Stayman work over a 1N opening? That is, the normal Puppet response to 3C is 3D to deny a five card major but say nothing about 4 card majors (unlike a 2NT - 3C sequence); one of the main benefits of Puppet is to avoid telling the opponents about opener's four card majors and there's never a need to (responder will either show his 4 card major next, or would have bid regular Stayman to begin with). So there aren't two bids to 'swap' like over a 2N opener. Also, is there a reason you prefer (14)44 splinters to (13)(54) which appear to be more common? Are you putting those through Puppet instead?

Change North's 6 of diamonds to the 6 of clubs and (after it decides Ace / low heart from dummy are equals) discarding is actually better double dummy: [hv=https://www.bridgebase.com/tools/handviewer.html?w=SAJ94DK732CAQT95&e=SKT72HA9532DJT5C2&d=e&a=pp1C1HD2H3SP4SPPP&p=HKH9H6D2&n=S863HKJT87DA9CJ64]400|300[/hv] I think GIB simulates a much smaller number of deals than people expect, so there's always a chance most of the hands it simulated gave equal results and the others were non-existent or balanced out the wrong way.

I was referring to the original holdings, not the remaining holdings. East starting with Axx is not a tie (even though it says it is double dummy), since you don't know this and would still be playing the king of clubs.

TL;DR: IMPs, best-hand. Will just do one week of registration (7pm, 16th November, NZT), but I'll PM past participants so they don't miss out.