r/bridge

Hello everyone,

I'm Zhiyuan, a Ph.D. student at MIT's Game Solving Lab. I've been developing a new Bridge bot called Miai, which learns Bridge from scratch without human gameplay data. To the best of my knowledge, this is the first full contract Bridge agent trained this way, covering both bidding and card play.

I made a small website where you can try it here:

https://bridge.miai.moe

One thing I found especially interesting is that Miai seems to have developed a mostly natural and interpretable bidding system. Its 1NT opening is natural, balanced or semi-balanced, roughly 13-17 HCP. Its two-level suit openings, including 2♣, are weak natural openings. Responses are natural by default, and many game/slam decisions are direct placements. I have not found clear transfer or relay structures so far.

I wrote up my current analysis of its system here:

https://bridge.miai.moe/systemd

I am not sure how strong Miai is against top human players, but it does beat the bots I've been able to test against. The version currently on the website is a weaker version that acts instantly due to computational constraints. In a 1,024-board duplicate evaluation, this version already scored +0.21 IMP/board against WBridge5, while the contracts it reached scored about +0.59 IMP/board by double-dummy analysis. So I suppose it is playing something meaningful.

I'd love to share this with the Bridge community and hear your feedback. Please feel free to try playing against Miai, inspect the system, and let me know what looks strong, weak, weird, illegal, or just interesting.

Bug reports, strange auctions, and general feedback are very welcome. You can also contact me at:

fanzy [at] mit [dot] edu

Thanks!

https://preview.redd.it/5cvbsz08qw1h1.png?width=2790&format=png&auto=webp&s=9305411e1034567abed81e1af5e35df2d6f74ff3

Has anyone been to these? I like the idea and as a couple we have only played in a club teaching environment and we worry that it would be too much of an ask?

I am doing some digging into inverted kaplan, where after partner opens, 1h-1s shows 0-4 spades and a limited 1NT, and 1h-1NT shows 5+ spades, both sequences forcing.

What happens after 1h-1NT, showing 5+ spades ? I presume some rebids are natural, but say you had a balanced hand such as 2-5-3-3, does it function like forcing 1NT where 3m is 3+. Partner could have 5-2-3-3 or 5-1-4-3 and hear 2x of a minor (3+). Seems like 1h-1NT takes away playing in 1NT and creates awkward rebids, am I missing something?

A common criticism of two over one game force is the necessity for some level of forcing NT. In recent years, many expert-level players have adopted a so-called "semi-forcing" NT, which is really just non-forcing. Nevertheless, the forcing NT does still remain popular. I decided that I would try to quantify the cost and benefit of either choice.

To do this, I generated 20,000 hands, using the Bridge Lab feature on Bridgetricks, 10,000 for a 1S opening and another 10,000 for the 1H opening. The spade hands were constrained to have 5-7 spades, and could have 0-5 in every other suit, with an HCP count in the 12-14 range. The heart hands were constrained to 0-4 spades, 5-7 hearts and up to 6 in either minor.

The paired responder hands were constrained to 0-2 spades, and up to 6 in any other suit for the spade opener, and 0-3 spades, 0-2 hearts and up to 6 in the minors for the heart opener, both in the 6-9 HCP range.

I didn't constrain this further, so that I could implicitly account for the frequency of hands where forcing and non-forcing NT might behave differently.

I also needed to define continuation rules. Given that the hands are quite constrained, this was relatively straightforward.

• Non-forcing: only rebid with a 6+ card major or 4-card side suit below the 2-level of the opening suit, otherwise pass. Responder then chooses between the two alternative, or bids a new 6-card suit at the 2-level. If opener repeats his suit, responder always passes.
• For forcing continuations, I tested two main ideas: with no natural rebid, opener either bids his lowest 3-card minor (better minor), or rebids clubs with as few as 2 cards (short club). Responder then passes if he can guarantee 7 cards in the suit, i.e., if opener only promises 2 clubs with his 2C bid, then responder only passes when holding 5+ clubs.
• I then tested two different variations of this, where responder either deferred to opener's major with 2 cards with top priority, or bid a new 5-card suit with priority. New 6-card suits were always bid with higher priority than deferring to opener's first major.
• Finally, I also tested the BART convention, which is normally used to show invitational values, just to to see the cost.

Below, please find a pivot table of the result from the 20,000 boards. In this simulation, the "Oracle" is simply what a double dummy solver gives as the best contract. Where two contracts give the same score, the listed contract is the higher ranked one, prioritising North over South.

https://preview.redd.it/13o7720dar1h1.png?width=720&format=png&auto=webp&s=07a3edbb9a296b36cd8ff15f283cdabd1a1a3f58

The headline result is that on hands where opener bids a major, and responder bids 1NT, the best forcing method simulated gained 7 points per board over the non-forcing NT, or about 0.35 IMPs. Where opener is very weak, this gain increases to 9 points per board.

On boards where 1NT is genuinely the best contract, according to DDS, the non-forcing NT outperforms forcing variants by 25-35 points per board, but these boards are not common enough to make up the difference where a suit contract is better.

Also of interest, is that bidding clubs with as few as 2 clubs generally outperforms bidding the better minor by quite a bit, but gives back a lot of that gain on boards where opener has genuine clubs, as responder cannot pass with less than 5 clubs. However, allowing responder to pass with 4 where the clubs could be 2 resulted in a worse result.

There also appears to be a very marginal gain for bidding 2 of opener's major ahead of bidding a new 5-card suit, but it is possible that this is within the margin of error.

The result was quite surprising to me, as normally the argument is that forcing 1NT creates a cost. If anyone wants, feel free to DM me, and I can send you my excel or the PBNs I used.

I wrote an article a while ago about not playing NT just because you don't fit. This is a follow up that contains a lot of practical examples!

This link is to my Patreon but the article is entirely free. Most posts and hand histories are -- I just didn't want to format the images for my website in a new article.

I found this site:
https://www.bridgeoutahead.com/
(many thanks to the developers)
In order to generate deals to import in other sites like BBO (it exports deals in .lin, .pbn, .html).
Not easy to use at full power, but many conventions have recipes ready to use).

hi all! i want to start off by saying i have a huge interest in bridge. im a student and i only began it this year when i joined a club, but i played some games and i have an urge to get much better at it. one thing ive noticed is everyone who plays seems to be really good at it, unlike something like chess. i feel like my pace of learning has been pretty good i can find games decently often but im a bit weak on slams. i’m really interested in competing and id like to ask if anyone can help me regarding learning intermediate-basics? i have screenshots of some contracts i found really difficult to play and some defensive questions.

Imp, all vul, you hold in the third seat :

KJT9

T87

A

K8532

RHO opens with 1D, do you pass or bid anything?

My reasoning, and the result :

>!Partner already passed so game is unlikely. Given the vulnerability I decided to pass. We actually had a game in hearts that my opponent found easily by doubling in the first place I ended up defending 4D which went doN -1. I want to believe that I made the good decision by passing and this one was bad luck. but Argine is riding me hard on that one, saying I should have doubled.!<

I am learning bridge, mainly online via No Fear Bridge lessons, and really struggling in practice with "planning the play" as declarer. E.g. when to count winners versus losers and what to do with that information, drawing trumps first or later, when to discard versus ruff a loser, which order to play the suits (i.e. everything!).

When I do a quiz on any of these topics, I get pretty much everything right, but when I am presented with a hand, it all goes horribly wrong, even at a total beginners' level. After going down, I can always understand the solution given, but the steps/order seem quite different each time. Obviously NT vs suit contract is a fundamental difference, which might be part of my confusion.

Is this just a case of playing 100s of hands and getting it wrong loads to build up experience through learning from mistakes? Or is there any "rule" like a certain type of hand calls for a particular approach? Any good resources to help with this?

Hello! Beginner here. I was taught to prioritize a 1 NT opening over a 1 major opening. My question is this: I have 5 hearts and all the requirements for a 1 NT opening. I bid 1 NT. My partner has 3 hearts. By not bidding 1 heart we miss the 8 card fit in hearts. Can you help explain the rationale a bit here? Thanks!

Reminder that there is a free Weekly tournament on BBO that runs for redditors -- it's a list of players that I maintain! DM me or leave me your BBO name to be added. It refreshes between Monday and Tuesday, and can be found on the Tournaments (Competitive) -> Free area.

I had some really bad boards this week and had a 55%. Come get me!

I would have bid 3 diamonds instead of 3 clubs. Mr Rigal is a better bridge player than I am so I suspect I'm wrong, but don't see how.

Hey r/bridge,

Growing up, my friends and I played a house-rule version of bridge we called "Casual Bridge" The big twist: instead of the standard 5 contracts (♣ ♦ ♥ ♠ NT), there are 12 different strains — each with its own card-ranking rules.

One example: a strain called Small, where low cards win tricks. A hand full of 2s and 3s — normally a disaster — becomes exactly what you want to bid on.

The result: every deal has something to play for. You're not stuck defending all game just because you drew weak cards.

I built a browser version of it. Sign in with Google, no install needed.

Casual Bridge

Still beta — happy to answer questions about the strains if standard contract bridge is your background.

I'm looking for a local bridge partner to play contract bridge with. I've been playing for 5 years and currently at an intermediate level. Please reach out if you know anyone who's looking for a bridge partner in Victoria BC.