smerriman

This isn't based on a sim. Basic non-simming GIB will invite with every single balanced 11 or 12 count. The human descriptions of its bids are totally independent from the logic used to make them - while they roughly match in most cases, there are a number of cases where they don't. As a side point, in almost every case, the possible hands that GIB may hold can't be described solely in terms of HCP / total points / suit lengths, which is all that human descriptions can state. That's why a lot of the time, you need to figure out the underlying logic behind why GIB made a bid, rather than learn what it means based on what the description showed. Of course, in this case, the description being wrong is just a bug (or GIB making the bid is a bug, take your pick), but it is consistent in what it does.

OK, so some may have not thought this possible, but GIB is considerably buggier than I thought. Setting the second point about played cards aside for a later date, I decided to test whether an 'impossible' bid by a human influenced how GIB plays. To do this, I set up a two way finesse: [hv=https://www.bridgebase.com/tools/handviewer.html?e=SKxxHAT9xDAKQCJxx&w=SAQJHKJ8xDJxxCAKQ&d=e]300|150[/hv] With East dealer, undisturbed, the auction will go 1NT - 7NT, while if I double 1NT, it will get passed out. (To avoid North pulling my double, I gave North 4233 shape as well, as gave myself at South the ♥Q as otherwise North sometimes stupidly threw it under the first heart honor. Varying the spots allows this to be tested at a teaching table with the ability to have different results each deal.) This is of course a 100% guess. The intention was to test whether GIB will think I have the heart queen for doubling, because that is somehow 'closer' to the 15+ points it's meant to show. But things got weird before I could get that far. When I pass normally as South: a) I led a low club 30 times. On all 30 occasions, GIB won with the Ace of spades and led a heart to the Ace. Huh? Shouldn't it play North for the heart half the time? Well, maybe there's a logical explanation - perhaps something about the spade suit makes it always win in dummy, and something about the heart guess makes it want to play it at trick 2. But.. b) I led a low spade 30 times. On all 30 occasions, GIB won in dummy. On 17 occasions, it led a heart to the Ace. On the other 13 it.. took an immediate finesse at trick 2! Never trying to drop the singleton queen first. Of course, double dummy will tell it in that case it's safe to lead low, because you'll be able to see the opponents' hands before it's time to make a decision. c) I led a low diamond 30 times. This is somewhat symmetrical to clubs, so based on case a), it'll always play to the king, right? Of course not, this is GIB. On 20 occasions it played to the king. On the other 10 it again took an immediate finesse at trick 2. But wait, there's more. I discovered that on 4 of those 20 times it played to the king, it then tried to drop the queen rather than finessing. So I went back and checked case a) 10 more times - yep, it always plays to the ace, then seems to always cash a spade and diamond.. but then 3 of the 10 times it tried to drop the queen, only taking the finesse on 7 occasions. I think if I work on this a little more, I'll be able to figure out how many sims GIB is doing. But whatever it is doing, it's not what it should be doing. I never did quite get to compare what happens when I double, but the behavior of the 'control case' is too extraordinary I don't think it will even be possible to compare..

This is based what random seed is used. After the seed is chosen, the random number generator will always give the same results, so equal bids/plays will lead to the same choices, and it appears that at a teaching table, the same random seed is always used. But a quick hack for forcing a different random seed at a teaching table is rotating the hands 90 degrees. I suspect the seed might be chosen somewhat deterministically, which is why it's easy to achieve equal seeds in a robot tournament. There was a post on BridgeWinners recently in a human tournament (but with many having robot partners) where every time the robot's LHO was a human, it played one card, and when the robot's LHO was a robot, it played a different card, despite everything else being equal.

No, I don't know for sure, but I would think it unlikely it was removed. Your example wouldn't be affected though - because whether you cash the ace or not wouldn't matter double dummy, so there would be no inferences to make. It's more about the Grosvenor type situation. Edit - actually, I see what you mean. Well, I don't know - seems strange given how BBO basically haven't touched the play engine at all that they'd delete half of the algorithm. His original paper - obviously the defensive signalling part was turned off..

This has been bothering me a long time. GIB works by simulating hands which match the bidding and play* so far, and then choosing the card that gives the best average score, double dummy. So why does it sometimes get it so wrong - such as steve2005's recent example? While we don't know how many hands basic GIB generates (barmar has said the advanced robots simulate "a few dozen"), when I ran the numbers, even simulating 10 matching hands would have a success rate of > 99.99%. The real question seems to involve going back one step. How does it simulate hands in the first place? Like Dealer does, there is only really one viable starting point. Randomly shuffle all cards that aren't in your hand / haven't been played amongst the other 3 players. Then test whether that is a 'valid' deal. If you ask Dealer to generate 500 hands where North has exactly 4-3-3-3, it will generate about 19000 hands in order to find 500 valid ones. The more tightly defined the constraints, the more hands it will need to generate in order to find valid matches. For example, when I considered steve2005's deal from West's perspective, it's only able to find about 80 matching deals after generating 10 million hands (and that takes about 10 seconds). In an earlier post from helene_t, it was coming up with only 0 or 1 match amongst those 10 million deals generated in 10 seconds. And of course, basic GIB, at least, clearly plays faster than 10 seconds per card. At this point you may think that we have an answer - if GIB isn't able to simulate matching hands, it just chooses cards at random. But that cannot be true; even when humans make bids that are 100% impossible, it's capable of at least some very basic trick taking - while it can occasionally throw away a winner late in the play, it doesn't just start playing every single card randomly from trick 1. So GIB therefore must have some logic built in that bulks up its simulated results with hands that are 'close' to what it knows so far. From a human perspective, we could think of some ways this could be done. For example, if someone has shown a certain point range, allow hands slightly outside that range. Or perhaps stretch something about the length or quality shown in a particular suit. That is something we could easily do when putting constraints into Dealer - if we have hcp(south)>=15, try hcp(south)>=14. Yet that is 100% impossible for GIB. There are no constraints it could loosen, because it has basically no understanding whatsoever of suit lengths or point ranges each player holds - those descriptions you see for bids are an estimate for humans, completely independent of the logic used for making the bid. All it has to go on is - does this hand make this bid by looking up the bidding database - yes or no? Even for a simple 1NT opening, the way the bidding database works, it has zero way of knowing if a hand is 'close' to making a 15-17 opener - either it matches the pattern, or it doesn't. So I started thinking - from a coding perspective, how could you actually do this? You've generated a random deal, have an auction, and a bidding database that tells you what bids would have been made - how can you tell if something is close? For steve2005's example, I was thinking perhaps it couldn't find enough hands where East doubled, and ended up adding lots of hands where East didn't double. But that appears to be lot more complex than it sounds at first sight - if you take away a bid in the middle of an auction, it completely affects every bid that occurs afterwards (especially given the database works based on finding what comes after a given prefix of all prior bids). And it would be a bit of a nightmare to code - consider every possible bid, try replacing it with some other bid, see if all of the future bids would end up being the same.. and if you still don't have enough results after doing that, um... I don't think that really works. A more codeable algorithm would be: - generate random deals - for each deal, step through the auction one bid at a time and count how many bids match - stop as soon as you find a single bid that doesn't match, because who knows what'd happen after that - sort the results by the number of matching bids - take the top N and perform double dummy analysis - weighting the results based on how many bids matched. But that would still comfortably result in a club being led in steve2005's example, since the double comes reasonably early on, and still is a clear favorite even if you allow South to have 3 hearts, or North to have non-Smolen hands, and so on.. So.. still not certain, and as usual would love to see the code to know for sure, but I can see lots of ways for GIB to mess up based on the way this has been coded. * Side point - an interesting fact from Ginsberg's original paper, often overlooked here, is that it doesn't just take into account what cards have been played to date - it always takes into an account a factor of whether they should have been played. That is, during the double dummy analysis, if a player didn't play a card, Bayes' rule is used to weight the deal based on whether double dummy analysis says they should be played it if they held it.

The latter is sometimes the problem; if it only uses a small sample and they're all exact equal, then it wouldn't know to lead a club. But I calculate about a 58% chance of a spade being strictly worse, so even a sample of 10 would result in a club 99.99% of the time. So yeah, can't even blame a poor simulation here. Robots always simulate during the play, it's the only way they know what card to play. (Cheap robots don't simulate during the *bidding*). Though the only explanation for some of these hands is that it failed to simulate and ended up playing a card at random, or something along those lines. Nobody knows..

Are you suggesting robots should be forced to lead partner's suit? I don't think that's a good idea. If a simulation (which takes into account what you've shown in the bidding) tells it that another suit is better, then it should lead accordingly. Of course, it often simulates poorly, but that's a more widespread and unrelated issue.

I guess it would have to be something like a spade void and 7+ clubs.

Hey, if this shows a specific enough hand like the 3NT bid, exactly the same argument applies there too :)

I don't have a fast internet connection, and live on the opposite side of the world, yet never get disconnected. While it is hard to judge - since everyone for whom it is working fine aren't going to report as such in the support forum - based on how rare the reports are and the numbers of BBO users online at any time, it seems to affect a very tiny number of users. BBO have stated in those threads they've never been able to replicate the problem. At least one person recently reported it immediately being resolved after they replaced their router as well. (You said there is nothing wrong with your internet, but the fact you are getting disconnected suggests there probably is - just that BBO requires a much steadier connection than other websites, so may make it more apparent).

No, though you can use a service like imgur.com.

To get a symbol of 2 next to your name, you need 1 point. See here. But yes, if you're not regularly finishing highly in tournaments, it's going to take longer to get points, so you're going to have to put more hours into it. But points don't "mean" anything, so I'd suggest just playing whatever you feel like playing and not worrying too much about them.

You have an *award symbol* of 3 by your name, which means you have somewhere between 5 and 12.5 points (it's a mainly exponential scale). And your forum posts have proven you're not a poor player :) BBO points are more about how *much* you play than how *well* you play. If the OP is solely looking to get points *quickly*, then you'll want to play in large robot daylongs. In an example daylong with 1300 entries, you can get 14 points in a single go by winning the tournament; while that's extremely rare, you'll still get 2 points by finishing in the top 10% of entrants, and half a point in the top 20% of entrants. You can also play in smaller tournaments like 8 board Instant Tournaments; in these you'll only get fractions of a point, but you can play heaps of them in a row to build up points. But the real question is why you're looking to get BBO points quickly..

The link opens a named window. This means the first time you export it, it will open a new tab / window / whatever. But future clicks will reuse the same one rather than open a second page. So if you've exported a hand but didn't close it, go back and check the window that hand exported to - you'll probably find it has loaded there with the new information.

You might want to provide some more exact details of what "it won't do any more" means. It works fine for me, so only a step by step list of exactly what you're doing, what you see, what you expected to see in each step can help debug.

See here.

How bizarre. Everything breaks after that too - if you ruff, West fails to play anything on the next trick, while if you throw a heart, you concede, but the hand layout all messes up. The logic behind BridgeMaster hands is very much manually hardcoded from one deal to the next to cover all of the important situations, so I guess there must be just a bug in this one. [Edit] oops, posted this before you edited in exactly the same things in your message :)

Which level? (And what were the first 3 tricks?)

I think you mixed up who was who - pescetom opened 3♣, so I don't think he'd do that with a singleton club :) It was the raise to 5♣ being congratulated. If I did pass as East, the next bid is easy (double 2♥), but things definitely get more complicated after that if South is bidding 4♥.. hard to know what'd happen after that as I'm a bit biased by seeing the hands. 6-5 is probably worth opening though.

Interesting. GIB is well known to pull the majority of (what should be) penalty doubles, but I always thought this was one of the sequences where you can actually get a penalty double left in. Take the classic case - nobody has a fit, but South can penalise anything: after the doubler escapes, GIB happily leaves it in: [hv=https://www.bridgebase.com/tools/handviewer.html?lin=st||pn|smerriman,,~~M6451o1s,|md|3S4HKJT7DA953CQT62,SQT862H862DQ74C53,SAKJ95H53DJT2CK87,S73HAQ94DK86CAJ94|sv|e|rh||ah|Board%2057|mb|1S|an|Major%20suit%20opening%20--%205+%20!S;%2011-21%20HCP;%2012-22%20total%20points%20|mb|D|mb|R|an|2-%20!S;%2010+%20HCP;%20opponents%20cannot%20play%20undoubled%20below%202N|mb|P|mb|P|mb|2H|mb|D|an|Penalty%20--%201-%20!S;%2010+%20HCP;%20biddable%20!H;%20opponents%20cannot%20play%20undoubled%20below%202N|mb|P|mb|P|mb|P|]400|300[/hv] Where GIB really falls down is that when West gives an immediate preference to a suit, GIB will often bid immediately, even with a boring hand at the 3 level, rather than make a forcing pass to see if you want to penalise first: [hv=https://www.bridgebase.com/tools/handviewer.html?lin=st||pn|smerriman,~~M1316she,~~M6451o1s,~~M2954q1r|md|3S4HKJT7DJ53CAKT62,ST8762H8642D87CQ3,SAKJ95H53DAT92C87,SQ3HAQ9DKQ64CJ954|sv|e|rh||ah|Board%20101|mb|1S|an|Major%20suit%20opening%20--%205+%20!S;%2011-21%20HCP;%2012-22%20total%20points%20|mb|D|an|Takeout%20double%20--%203-5%20!C;%203-5%20!D;%203-4%20!H;%202-%20!S;%2012+%20total%20points%20|mb|R|an|2-%20!S;%2010+%20HCP;%20opponents%20cannot%20play%20undoubled%20below%202N|mb|2H|an|Length%20--%204+%20!H%20|mb|3D|an|4+%20!D;%205+%20!S;%2011-21%20HCP;%2012-22%20total%20points%20|mb|]400|300[/hv]

While I don't understand anyone that bid 3NT over 3♣ (3♦ seems clearcut), I wouldn't be too comfortable with a 4♣ raise. Won't that guarantee a near bottom every time partner has no slam interest? (Or in fact any time we're not making slam, whether they have interest / we bid it or not).

+silentspecs+ means kibitzers can only chat to each other privately, rather than it going to the table.

Virtually is the key word. All you need is a single table not in slam to make the safety play average above 50%. That is, assuming the two finesses are 50%. In the BridgeMaster example, East started with 9 minor cards to West's 7, so after being forced to finesse West for one, you're looking for split honors, and the two-finesse route loses as often as it wins. But if the AQ were in South, the odds would favor finessing twice.

https://us1.campaign-archive.com/home/?u=4e98d7d6525c3b9a8a3c9bdd7&id=201fb1d8f4

I'm not sure what you're referring to - the link above doesn't say anything about 5 levels; it shows levels ranging from 2 (1+ points) to infinity (eg 22 is 2200 points). Are you talking about something else?