Free Lecture Series
Matchpoint and Robot Strategies
On Saturday, February 17, at 1PM US Eastern Time (7PM Central European Time), we had a special 1 hour teaching session with star player BBO Star JDonn (Josh Donn). The topic was MP and Robot strategy. The goal was to prep the heck out of players planning to play ACBL's Spring NABC Online Individual. For the BBOers who were not able to attend the lecture, let's dive into the review now.
Hi everyone.

With the upcoming ACBL online event March 5-7, I thought it would be a good idea to talk about a helpful topic for that event. The event is contested between humans, but each human plays at their own table against GIB, the bridge playing robot. It would be useful to discuss how playing against a robot changes your strategy. Let’s talk about how the robots defend. The robots think about defense differently than humans do, so I want to take a look at that. I will start by explaining how the robots think about defense, and then give some example hands.

For one thing, the robots don’t signal. They play spot cards randomly as far as high/low or low/high. So there is no inference to be drawn from any signals they make. But this ties into some related topics. First of all, false-carding. The robots make lots of false-cards in situations where it can’t technically cost, but humans might not think to make them. Notice I said "technically" can’t cost. GIB doesn’t account for a human mis-guessing, and that is important. For example, here is a suit combination. Let’s think about it from the perspective of a defender.
Look at only the spades in the North/South hands here. Forget the other suits, and forget the East/West hands. The KQ98 is in dummy.



Suppose the defenders have a count and know you have three cards in this suit. You lead the 2 from hand, west putting in the jack. You win in dummy lead back to the ace, and lead the third round, everyone following low. You now have to decide whether west played the jack from JTxx or Jxx. Here is how I would think about this suit.

Against weak human defenders: They probably learned to play jack from JT holdings, and they would never think to play the jack from Jxx for any reason, so I will finesse.

Against strong human defenders: They would never play the jack from JTxx, since I would not know to play the 9 if they played low. They must be testing me with Jxx, so I will play for the drop.

Against GIB: GIB knows that to play the J from Jxx won’t technically cost, no matter where the ace and the ten are, so he could have that holding. He also knows that to play the J from JTxx won’t ‘technically’ cost, since I ‘could’ play the 9 if he played low, so he could have that holding too. I can’t draw any reliable inference from the jack play, therefore I will have to look elsewhere for clues, such as the distribution of the other suits.

In this sense it can be trickier to play against GIB than against humans, although the offsetting benefit is you might pick up the JTxx holding where against strong players you never would have.

What else should we know about how GIB thinks about defense? Well, the biggest difference between a GIB defender and a human defender is on opening lead. GIB makes very passive opening leads relative to human players, often leading from short and weak suits against notrump contracts. Humans like to be practical and lead from long suits, hoping to set them up and run them. GIB prefers to try and avoid blowing tricks on opening lead. So let’s take advantage of that by bidding 3NT contracts without worrying about weak suits! Here is a bidding problem:

You hold the north hand here: ♠2 KJ84 97 ♣AQT853

Partner opens 1♣, you respond 1, and partner bids 1N. Your bid? You might consider trying to play the hand in clubs. It will be a very safe contract, and since GIB doesn’t rebid 1NT with four spades, you know the opponents have a lot of spades that they might run against notrump. Even though you seem to have lots of fast tricks, that only matters if you can get on lead first. But we also know GIB doesn’t like to lead from length, and he seems to have four or five spades. So I would take the bull by the horns and rebid 3NT, not even giving the spades a second thought! Perhaps the whole hand is as shown:



Against 3NT, any human would lead a spade and beat the contract quickly. But GIB tends to avoid such leads, which might give up a trick outright in many different possible ways, such as declarer having Qx and dummy having Kxx. In fact, GIB usually leads a club from this hand, which is the least likely to blow a trick in the suit. After that, 3NT is easy. This is the kind of layout I hope for when I rebid 3NT. The exception is that GIB would lead a spade anyway from a strong sequence KQJ or QJT, but otherwise he will avoid the length lead most of the time.

Let’s look at another hand where it’s important to note GIB’s proclivities on defense when you declare



Does that spade suit look familiar? Suppose as south you open 1NT showing 15-17, and after stayman, no major, partner bids 3NT. You are fortunate to receive 3 of spades lead rather than a heart. You play the 8 from dummy, third hand plays the jack, and you win the ace. You run four rounds of diamonds in case something useful happens, both opponents pitching a club on the fourth round. You lead a spade to the king, a club to the ace, a spade toward dummy, and you....

Well against most human players, this is easy. They led fourth best against notrump, and furthermore east’s jack play usually denies the ten. So you finesse. Against GIB it’s also easy, but in exactly the opposite direction. You must play for the drop. First, there is no inference from the jack play from east. He might just as well play the jack or ten from JTx. And as for the lead, GIB simply prefers leading from three small rather than from four to the ten, since three small is much safer. That is a very strong inference, to the point that I don’t think there is even anything else to really think about.

I want to take a moment now to invite everyone to play in the ACBL NABC Online Individual. It runs for three days, March 5-7. It is open to ACBL members, and $40 to enter – a great price in my opinion for 3 days of a major event. You play hands at any time of day that you want, each day. The event awards coveted gold and red masterpoints, and will have thousands of players entering which probably means hundreds of awards!

BBO is also running free practice tournaments for this event today and tomorrow. So why not enter and give it a try? It’s completely free, and should be great fun. To find the practice tournament, go to the front page of BBO and click on ACBL World.

Thanks everyone. I will be happy to take questions now. Questions about GIB, or the ACBL events, or the hands I showed today, or any related topics are fine.


Q1:How does one survive slam auctions with GIB?
A: Well let me give a few tips about slam bidding with GIB.
1. I would avoid cuebidding auctions, or at least cuebidding beyond the level of blackwood. GIB doesn't handle them well, so you will usually do better by just bidding blackwood yourself and making your best judgment.
2. If GIB cuebids, it plays aces only, it will not cuebid kings or singletons.
3. Always mouse over your bid to make sure it means what you want it to, including the strength you want it to. The programmers work on these bids a lot, but there are still a few with weird meanings.

If you hover the mouse over a bid before you make it, you can see the definition to know how GIB will take it. It will prevent you from accidentally misbidding. I think those are the most imporant tips for slam bidding with GIB.


Q2: How can you use RKCB but play a slam in a different suit?
A: You can't, so don't try it.

If you bid RKC for clubs and then jump to 6♠, GIB is likely to just put you back in 7♣.

There are many ways you can manipulate GIB but this is not one of them. The only exception is you just generally place the contract in 6NT after bidding RKC, but not in any suit other than the one you bid RKC for.

Q3: Someone playing with GIB today had a action about he want to ask. Bidding spades, robot bid 4 no trump and he responded five hearts as he had two aces. Robot then went to five clubs.... What does he mean?
A: We better get the auction straight, because 5♣ was an insufficient bid. Anyway I can't really answer without having the whole exact auction, sorry.

Q4: Does the GIB convention card say, "passive opening leads," and are the bots programmed to know that opening leads are "passive?"
A: That's a difficult question to answer. GIB doesn't know the definition of a word like "passive".

What happens is GIB simulates hands consistent with the auction, and finds what opening lead works best, on a double dummy basis. Double dummy bridge is different from how people play bridge, since you can't see all the hands.

For people, the easiest way to beat a notrump contract is to set up and run a long suit. But often this can give up tricks too. GIB simply prefers leads that don't immediately give up a trick. It is pretty consistent making passive leads against notrump (with the exception of sequences, as I said). Not 100% but probably over 90%.


Q5: Sometimes the Gib DOES lead from a long suit vs NTs- is there any way to guess when?
A: It's kind of like asking, how do you know if a person led from a short suit against notrump? They don't usually do it, but occasionally they do. It can possibly fool you if that happens. I can tell you what is most likely, but there are never guarantees with GIB.

Q6: Opps are playing the hand after I open/overcall a suit. When GIB doesn't lead my suit, can I make any assumptions about what it does/doesn't have?
A: That is a very general question. If it's a notrump contract, it is just constantly looking for the safest lead. But it's hard to answer without a hand or auction.

Q7: Auction: i opened 1nt P 2 - transfer - P 2♠ P Robot invited 3♠ with 8points I accepted with 16 point hand. Did bot mess up or did I?
A: Who says anyone messed up? I think I made a game once with 24 points :) Bidding and point count or not exact sciences. There simply isn't the bidding room for that. It's estimates.

Q8: GIB often makes a weak take outs into a minor opposite 1NT. Sometimes 3NT would be easy. Is it best to ignore the weak takeout on the long run?
A: Say you open 1NT, and GIB signs off in a minor. Sometimes it has a reasonable hand and you can make 3NT.

In real life here I would need such a perfect hand to overrule and bid 3NT, like Axx Axx Axx Axxx if he signed off in clubs, needing only six to the king.
I think you can overrule GIB more often than that because he doesn't invite in minors, he signs off or bids game. But in general I would just pass, he could have a bad hand too.

Q9: Can we Psych successfully against GIB, 1) Outright Psych 2) tactical psych to avoid lead or make forcing bid?
A: You are certainly welcome to. Some psychs work better than others.

Can tell you, for example, that some people like to open in their weak minor with GIB, like xx of diamonds and AKJx or clubs they open 1 in an attempt to fool GIB. Have found that works very badly for several reasons. For one thing, sometimes he passes the opening bid, and you play it there. This happens much more with GIB than in real life.

For another, he might raise to 3 of the minor weak, and you are kind of stuck if you don't have a good enough hand for 3NT.

And also, even if you end in 3NT, remember GIB likes passive leads. It may decide leading the suit where you showed length is safest. Sometimes by opening the suit you actually talk GIB into leading it! But of course other times it can work very well. It's a free country/planet and you paid $40, so you are welcome to try any strategy you like.

Q10: Does the GIB lead just mean short suit? Or is that only in NT?
A: I was really talking about leads against notrump. I could have been more clear on that point.

Q11: I have played daily against robots and, while at times I do well, it seems the distribution of my scores is more random in MP play than indicative of my play level. Please comment.
A: Well that might just be because the tournaments with GIB are 12 or 8 boards long, in real life you usually play 24-27 in a session. So a shorter session means a wider variance in scores. That is the first reason that comes to mind. Otherwise I would have to see how you play to really answer.

Q12: The, ♠2 K854 97 ♣AQT853 hand only has 9 HCP, will there be ACBL regulations for opening in a minor with less than 10 HCP?
A: No, nothing like that will be enforced. The thing with GIB is, he has no memory. If you open with 9 or 8 or 7 points with a human partner, they will see that you did it, and remember from now on. That's what makes it (arguably) unfair, or at least worth considering.

GIB will just play the next hand assuming you have your bid like usual, so psyching with GIB is actually much more fair than psyching with a human partner.

I am not saying opening that hand is a psych by the way, but I think that's the gist of the question. Pretty much you can bid anything you like with GIB in this event. But if GIB hands you, that's the price you pay.

Q13: I often find my hand does not fit the description of bids available according to GIB when I rollover my options, How do I "fool" the robot?
A: If there is no bid available that fits your hand, you just have to choose among the available options.

If slam might be in the picture I would not recommend the overbid as GIB often hangs you. But it's hard to give general advice on this topic other than, do the best you can.

OK last question.

Q14: Any tips on bidding game or not in the tournament?
A: Bid game and try to make it. In bridge, they pay more for games!

Ok thanks for coming everyone. Have a good day all.


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