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This is fascinating that it worked though. Can we just merge all the open weight models and get something better?
Merging related models has been a very common practice for years. See the Stable Diffusion community.
The model's webpage at https://huggingface.co/prefeitura-rio/Rio-3.5-Open-397B says it's a merge now. It previously didn't contain this paragraph:

>The model is built via a merge of https://huggingface.co/nex-agi/Nex-N2-Pro and https://huggingface.co/Qwen/Qwen3.5-397B-A17B, proceeded by On-Policy Distillation from a stronger model. We detected an incorrect upload in the previous version, where the base merged version was upload instead of the final distilled model. We are sorry for the confusion and apologize profusely.

Incidentally are people using Github issues as blogs now?

Oh no, someone is profiting off of their work without proper attribution!?!?
How do you feel about the government or government contractors saying they did a bunch of work when they did nothing instead?
Wasn’t it already obvious given the awfully familiar parameter numbers?
That only tells what base architecture they used, but fine tuning does not increase the number of weights, it just adapts the weights to improve better on a fine tuning dataset- something they claimed they had done
One funny thing about incompetence is that they don't have the competence to know that their incompetence is straightforward to verify by a competent person.
I'm honestly surprised that they even had the inclination to attempt creating a model. I guess it's bullish that a municipal IT department had the guts to try this?
Merges and fine tunes are within reach of individuals with some money to burn so I’m sure a muni can do it
I like the [dead] comment theory that they proposed a huge LLM training budget to the government, kept most of the money, and released a cheap merge to justify the grift.
Didn’t the last thread about this have someone from the lab or an enthusiast in Rio saying exactly that?

Its a fine tune of Qwen

Not a conspiracy

“Well, Steve (Jobs), I think it’s more like we both had this rich neighbor named Xerox, and I broke into his house to steal the TV set, but I found out that you had already stolen it.”

-- Bill Gates

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> Every weight tensor in Rio is, to thousands of standard deviations, the same 0.6/0.4 blend of Nex and Qwen — across all 60 layers and every component of the network. Other finetunes cannot be explained as interpolations.

I find it amazing how robust the current deep learning models are. A simple linear combination of every weight did not degrade the performance of the model, but enhanced it.

This works because Nex itself is a finetune of Qwen3.5 (https://huggingface.co/nex-agi/Nex-N2-Pro). It's merging Qwen3.5 with a Qwen3.5 finetune.

I don't believe this would work on two LLMs that have different pretraining. Even if it did you would need two LLMs that have exact same internal activation shapes, dimensions, expert counts, token vocabulary, realistically it would never happen outside of finetunes or academic experiments.

> A simple linear combination of every weight did not degrade the performance of the model, but enhanced it.

Enhanced it on a couple benchmarks, supposedly.

The game is to turn knobs until you get a benchmark run that shows an improvement, then ship it. There are a lot of fine tunes and chimera models on HuggingFace that are supposedly better at some specific test, but when you use them for anything else they're usually worse.

This happens with a lot of the models that are modified to remove censorship. They succeed in getting the model to emit previously censored outputs, but the overall output quality decreases.

It shows that LLMs are an extremely wasteful approach to intelligence.
> A simple linear combination of every weight did not degrade the performance of the model, but enhanced it.

Which could be a signal that your "performance" was so abysmal in the first place that even randomly applied training methods can't make it _worse_.

If this is true, it really would be impressive.
What I find fascinating is the idea that there might be a set of "secret" tweaks that when applied to those weights (or even smaller models) could result in an intelligence simulation that could vastly surpass even something like Fable.
This is called linear mode connectivity and seems to work for almost every large model. So well that in most cases it’s an explicit part of the training process; do many training ‘branches’ then merge then continue.

It is not understood why it works so well.

it's interesting that this was even guessed at
Can someone please explain or link to some information about how models are merged? Is this genuinely merging weights mathematically or some kind of distillation (presumably not if they’ve done zero training as the post suggests).
There’s nothing to read.

Model A: A_1, …, A_n Model B: B_1, …, B_n

C_i = A_i * p + B_i * (1 - p)

In other words, it’s just a linear combination of the other models’ weights, per position.

WHAT!? There are thieves in Rio de Janeiro?

Oh, I am so SHOCKED, so SHOCKED! /s

Explaining the joke: in Brazil, Rio de Janeiro is known as "Terra de bandido" (Gangster's Land).

Kinda like Chicago in the 20's or Naples and Palermo in the 90s.

Nex in turn is also based on qwen so don’t think they’re too far off
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It's absolutely insane to me that we are now at a point where the top of the front page of hacker news is a random GitHub issue about attribution to some random LLM merge, written in just the most disgusting AI slop style.

I would like to downvote this please.

I have no affiliation with them but here's what I think happened:

1. They claim the official model is based on Qwen 397B. It's likely they didn't disclose Nex Pro at all because Nex itself is based on the same base model (not saying they shouldn't).

2. The improvement would come from merging the weights PLUS on-policy distillation. The confusion is that the uploaded model didn't have the distillation at all.

3. It's important to notice they didn't advertise the model besides posting it on Reddit 2 days ago. It became viral organically, over the weekend, and during Brazil's World Cup debut (Brazilians will understand). Of course the mayor of Rio took the opportunity to capitalize over the free coverage, but that wasn't done in conjunction with the researchers.

4. I don't see why they would disclose Qwen 397B as base and mention the SwiReasoning paper but not mention Nex if all they did was to merge both models.

5. In any case, what they are claiming is easily verifiable once (if) they upload the right model.

It seems to me this is clearly a mistake. They would not even have the resources for it as far as I know and I think they are not even on a position to such bold claims.
an eternal 7x1.. and I am not talking about Curaçao..
They really missed out by not calling it Neuromancer.