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Posted by sanity 23 hours ago

Show HN: Mediator.ai – Using Nash bargaining and LLMs to systematize fairness(mediator.ai)
Eight years ago, my then-fiancée and I decided to get a prenup, so we hired a local mediator. The meetings were useful, but I felt there was no systematic process to produce a final agreement. So I started to think about this problem, and after a bit of research, I discovered the Nash bargaining solution.

Yet if John Nash had solved negotiation in the 1950s, why did it seem like nobody was using it today? The issue was that Nash's solution required that each party to the negotiation provide a "utility function", which could take a set of deal terms and produce a utility number. But even experts have trouble producing such functions for non-trivial negotiations.

A few years passed and LLMs appeared, and about a year ago I realized that while LLMs aren’t good at directly producing utility estimates, they are good at doing comparisons, and this can be used to estimate utilities of draft agreements.

This is the basis for Mediator.ai, which I soft-launched over the weekend. Be interviewed by an LLM to capture your preferences and then invite the other party or parties to do the same. These preferences are then used as the fitness function for a genetic algorithm to find an agreement all parties are likely to agree to.

An article with more technical detail: https://mediator.ai/blog/ai-negotiation-nash-bargaining/

92 points | 34 commentspage 2
mfrye0 8 hours ago|
I would love something like this to use with my HOA. About to start mediation and the estimate for the mediator alone is ~$20k.
sanity 1 hour ago||
Thank you! You should definitely get a lawyer to review any agreement before signing if there is meaningful money at stake.
wferrell 8 hours ago||
You might try Decisionlayer.ai

We built a way to make contracts enforceable and resolve disputes without the high cost of litigation. Specifically, by adding our arbitration clause to your contracts or using our "case by consent" you can get AI driven court-enforceable arbitration decisions in 7 days for a $500 flat fee - no lawyers required. This compares to the $30k or $40k you would otherwise spend on a lawyer+ JAMS/AAA arbitration fees. For your HOA, I suspect the case by consent would be the best approach - two parties come to the website, both agree to use DecisionLayer to resolve the dispute and then present the issue and each side's argument.

We have free case simulator on our site. Check it out at https://www.decisionlayer.ai/simulate

arowthway 4 hours ago||
I'd rather arbitrate by coin toss.
mukundesh 8 hours ago||
How about Iran/US conflict ? or Israel/Palestine conflict ?

Is anyone working on this ? seems like a big win for AI if it can be done.

sanity 1 hour ago||
Believe it or not I did a lot of testing with geopolitics early on but didn't want to put it on the website so people wouldn't think I'm a megalomaniac ;)

I regenerated the Israel/Palestine agreement using my latest code although the input positions were as they were this time last year when hostages were still being held.

Interested to hear what you think: https://gist.github.com/sanity/3851e33e085ed444525edcc7b7ba2...

harvey9 2 hours ago|||
Seems like a very different class of problem. Many more parties and variables than the 'roommate problem'.
watwut 6 hours ago||
Pakistan is working on the Iran/US conflict.
Zababa 4 hours ago||
Very interesting! For limitations, I'd add stated vs revealed preference. Currently the system assumes than what people say is what they actually prefer, but that's not always the case. If that is already addressed in your tool, I think it would be nice to mention it!
sanity 18 minutes ago|
Thank you. The purpose of having the LLM interview the user is to try to surface those unstated preferences by exploring aspects of the agreement that the user may not surface themselves.
watwut 6 hours ago||
Basically, the negotiating game is will break down to demanding absolute maximum and pretending you care a lot more then you care. The more demanding person gets more, less demanding person is taken for a ride.
eigenket 6 hours ago||
I don't know anything about this specific LLM thing but if it correctly uses the Nash bargaining optimiser then that won't happen.

This thing you point out is exactly why Nash demanded invariance under affine transformations in his solution. Using completely arbitrary units if I rank everything as having importance 1 million, that's exactly the same as ranking everything as having importance 1, and also the same as ranking everything as having importance 0.

The solution is only sensitive to diffences in the unitity function, not the actual values of the function. If you want to weight something very strongly in the Nash version of the game you also have to weight other things correspondingly weakly.

sanity 45 minutes ago||
You are correct that Nash should address this because only the relative utilities matter, not absolute.

There is the potential for parties to get better deals by overstating their BATNAs, but then they risk the other party rejecting the agreement when a mutually beneficial agreement was possible - so it's not in their interests to mislead the system.

DeathArrow 6 hours ago||
Then the tool should be named Trump.ai, not Mediator.ai. :)
setnone 7 hours ago||
definitely a great use of LLMs
arjunthazhath 9 hours ago||
I am unable to login
sanity 1 hour ago|
Hi, what happens when you try?
mock-possum 8 hours ago||
EDIT - in all fairness I find the blog entry much more persuasive: https://mediator.ai/blog/ai-negotiation-nash-bargaining/

That said, given the fictional example:

Honestly I’m on Daniel’s side - they agreed on a 50/50 split, and they’ve both been working their asses off to make the business work. It’s an arrangement that clearly both of them have been actively participating in, not trying to push back against, for a year and a half.

And the supposed insight this product offers is to… split the difference? Between Maya’s power play for 70/30, and Daniel’s insistence on the original 50/50? 60/40 is the brilliant proposal?

How could they stand to work together afterwards, knowing she thinks she deserves 70% of the profit, but was willing to ‘settle’ for 60%? Why would you want to keep working with someone who screwed you over that way? Their partnership is toast. All the mediation really does is… I don’t know, what? How is this good for Daniel? This ain’t any kind of reconciliation, surely.

Is the argument that it’d be easier for her to get a new baker, than it is for him to get a new business manager?

AnthonyR 7 hours ago|
Yeah I also don't quite understand the example on the homepage... they agreed to 50/50 and then she wanted 70/30 so now they settle on 60/40? Like this doesn't seem like a "fair" mediation it's kind of weird (obviously oversimplifying the situation a bit but nonetheless I'm not sure real world conflicts are this simple in practice)
sanity 28 minutes ago|||
You raise a good point. The issue is presentation - leading with the 60/40 reads like midpoint arbitration, whereas the interesting part is Daniel's path back to 50/50, the management salary, the mutual waiver on the first 18 months (which is what settles his rent contribution), and the shotgun buy-sell.

I've made some changes that should help with this.

alex43578 7 hours ago|||
They wanted 50/50, but from the vignette Daniel didn’t continue to do 50% of the work.
mock-possum 6 hours ago||
Sure, he just continued to take sole responsibility for the production of the product, quality and quantity, while also holding down an additional job, which paid the rent.

These characters have both been putting the work in.

I’d be looking for a serpent at his partner’s ear, planting poisonous suggestions that she deserves more of the company they started equally. If this were real.

lookACamel 6 hours ago||
> While also holding down an additional job

That's the problem, the story is saying he stopped focusing full-time on the business in order to make his own ends meet. It looks like the main innovation of the mediator generated deal is that it attempts to reconcile by drafting a way back in to 50/50 if he recommits. The starting 60/40 split is not that important.

gavinray 1 hour ago|||
He paid her rent
throwanem 4 hours ago|||
Her ends, too. They share an apartment, in the story.

This is certainly an example of what I would expect from a product designed to optimize a prenup. You know, they say money ruins people, but sometimes you just have to acknowledge there was nothing really ever there decent to begin with.

lookACamel 54 minutes ago||
Yeah after re-reading the scenario it is pretty weird. The AI doesn't have enough data. There should be concrete numbers for the rent. Why wouldn't Daniel tell the LLM exactly how much it was?
throwanem 46 minutes ago||
Well, I don't know, I'm sure. Totally unrelated, I hear a common piece of advice for the aspiring con artist is to avoid overcomplicating the legend.
Daffrin 2 hours ago||
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openclawclub 4 hours ago||
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