Stefan_O

Yes, looking at the description here (if it is correct) the X doesnt really show anything other than a couple of points more than 2H did. It doesnt say "penalty double", "biddable hearts" or even "2+♥". So understandable if North continues to bid -- not because the X is "forcing", but simply because the simulation does not show that 3H is likely to go down. What I feel is a recurring issue when playing with Gib, like this situation, is that you sometimes really dont know what your own bid or Gib's bid really means to the robots. On this hand, is it that the bidding-system - as described in the database - is kind of defect and the X actually means what the description say (i.e. almost nothing)? Or is it just the description that is wrong/incomplete and the bid actually has some more meaning to the robots than what the description says?

You dont mention what 1NT-2NT is in your system... I assume it's conventional, since it seems responder here bid 2♣ without a major? In that case, you CAN play in 2NT without a stopper, but opener must bid 3C (not 3NT) with max and no stopper. Otherwise, this is a good illustration why it's a really bad idea to use 2♣ without major, since it gives away info only your opps have use of, and also gives them this opportunity to lead-double (or sometimes overcall on the 2-level). More efficient to have 2NT natural, and never bid 2C without major. If you bid this hand, 1NT-2NT-3NT, likely you would get a major-lead.

http://i.imgur.com/7jtshga.png When you see dummy, maybe you wish you were in a slam. And with favorable layout, you may have 13 tricks. But if not so favorable (assuming East has 6 spades), you might first want to duck the lead of SJ, in case West wins a trick along the way? And should you attack the diamonds first or clubs first? What is you plan at MP play?

Diagram

Diagram Haven't seen this kind of goof-up before from Gib. Seems normal to bid 4♠ over 1NT. Looks like responder can see 6-2 ♠-fit and has 14TP vs an opener... At other tables, they responded 2NT instead of 2♦, and Gib then jumped to 4♠. The only difference I could see in descriptions was 2♦=12-13HCP, while 2NT=12-14HCP

How does Gibson (single-dummy solver) actually work? Is there anywhere a readable description of the algorithm?

Yes, skill-levels or ratings, over all, should be determined by the software based on previous RESULTS, not dreamed up by each player him/her self -- it's currently quite useless. Some people apparently vastly over-rate their own abilities when they put "Expert/Advanced", while I also see quite commonly players with 5000+ logins or so, being "Beginner/Novice".

Thanks Stephen! Didnt know abt that one.... But, gosh, what a mess!! :blink: :unsure: Suddenly -- if this is the notation still used in Gib -- it seems much more clear now why it is not so easy to make fixes/maintain :huh:

If I would like to experiment with my own automated bidding algorithms, anyone here knows if there is any open/freely available bidding database/library, similar to the meadowlark(?) that Gib uses? Something one could start out from and try to improve upon...? Writing everything from scratch, seems like a pretty huge task... I also wonder if anyone has published/suggested some useful notation/language, etc, for describing a complete bidding-system in such detail as required for serious automated bidding. ps. I've had a look at gnubridge, but that's way too rudimentary.

Would make more sense the other way round.... After rebid, cannot possibly be takeout, since we didnt takeout-double on the first round. But after new suit, say: 1C - 1NT - P - P 2D - X the Double, logically, would show a 4-4-2-3 maximum.

Hm... so in a context of standard natural systems in varous countries, is it fair to say, in North Am it show 3+diamonds, while in EU it is 4SF?

You're right. My bad. So, back to the OP mystery, then.... How can the discard of ♥King make sense? Is it a BUG after all? :)

You bid 1♠ with only 3-card suit? That doesnt seems like 2/1?

Easy --- just twist your computer 90 degrees.

From my experience, declaring against Gib, when the simulations show two or more cards make the same result double-dummy, it will usually (always?) discard the highest. Since East here can see dummy's Heart suit, and also infer that West has a very weak hand, it might well be that the double-dummy simulations here all show it doesnt matter if it discards the King or a small -- therefore choses the King. Since North's 3♥ bid shows 3 hearts, declarer will always score 4 heart tricks anyway. This strategy of throwing the highest of equivalent cards often works OK, and sometimes can actually fool you, particularly as long as you as declarer has not totally learned about this robot-habit. But not so well, in all situations, where declarer would otherwise have some kind of guess, of course. It looks silly on hands like this, but the current robot-algorithm has no concept of when throwing a high or low makes life harder or easier for declarer. But I think, yes, BBO should definitely review, if this "discard-high" strategy is really an overall winning one? (Maybe they already did, I dont know....) It certainly has happened, that I was in a tricky high-level contract and pondering what suit to attack, then draw some extra round(s) of trumps, and Gib would needlessly throw away a sensitive card, that saved me from guessing. I'm sure "discard-low" also has its issues, though you might not actually notice them so readily, because they dont look so conspicuous as this example. And if you randomize between high-or-low discards, well, then you will still see behaviour like this deal, some of the times.

Aah, how could I miss that? :D Thanks!

Would like to know, playing 2/1, what is the "consensus" view here: 1♣ - 1♥ 1♠ - 1NT 2♦ What does 2♦ mean?

Unfortunately, that's not possible. You have to follow the Gib system -- or be damned :D

In the BBO Forums, how do I create a Poll? Cannot find the button for that... :)

I meant extras relative to his minimum limit :) 1NT is pretty wide range -- like 6-10 or so... What abt a minimum 4315 (or even 4306 at MP) with ♥HHx or so? Opener has not shown a balanced hand here... Well, once in a blue moon it might be better than NT perhaps... :) But if accepting game-invite, even if 2♦ is artificial, responder can still show 5+suit with 3♦, if he feels unsure where to play.

Really? I think that's an uncommon minority view...

But again -- Why? If you open 4144 with 1♦, the only time you can even have a ♦-suit is the rare 4045. What you normally are interested to know here is: - Does responder have 4 or 5 hearts? - Does responder have extra strength or not? Wanna play in diamonds? I think (almost) never... Much more likely to only help defenders by bidding 2♦ naturally...

Well, that's easy --- for penalties! :) That one is more tricky... :) If "garbage stayman" is part of your agreements, it seems 3♦ should now show such a hand. If it's not, you should not use 2♣ in the first place. Additionally, it seems doubtful, if West should Double at all when he indeed has a 4-card major after responder's Stayman. Obviously depends on suit-qualities and vuln, too...

But why should 2♦ promise anything at all about the diamond suit? I believe (hope :rolleyes: ) most decent pairs play it as 4SF. With your example-hand, 2NT seems like an obvious way to invite. And with 4144, you open 1♦, not 1♣.

Seems complicated.... what do you then bid when you have a normal 2♥ or 2♠ overcall? The standard defence against 2♦ Multi when you have a hand suited for take-out Double of either Hearts or Spades is that you first PASS, and then make a take-out Double on the next round, if opener shows your short suit.