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VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

arxiv.org

11–20 of 226 posts

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#11
post #4

I tried generating the classic pelican svg, but it failed horribly just showing me a rectangle and a black circle...

That’s all I needed to hear

As in, you learnt that a useless test that no one should be using was tested here, that's what you meant right?

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#12
post #9
post #4

I tried generating the classic pelican svg, but it failed horribly just showing me a rectangle and a black circle...

I think this is predicted? Part of the story is how they were able to preserve core reasoning ability while cutting knowledge like "pelicans have wings." > these findings motivate the Parametric Compression-Coverage Hypothesis, which views verifiable reasoning as compressible into compact reasoning cores, while open-domain knowledge and general-purpose competence require broad parameter coverage over facts, concepts,…

The only real essential item here is tool calling capability is it not? So I assume they tested a strong read/write/edit tool consistency?

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#15

Having some success while testing this model out as a replacement for GPT-5 nano in source code security review. Running on RTX 3090 (24 GB VRAM) via vLLM. It's not great on structured output (as noted in the model card) but I'm working around that in my harness.

Can't you just force it to do structured output via constrained generation?

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#16
There is some base level of intelligence any model needs to be useful, even in narrow tasks.

Could you teach a 5 year old to drive a car? A 10 year old? A 12 year old? To drive a car requires being able to read, to have judgement about ice or rainy conditions, to anticipate a child running after a ball. By the time a human in in their mid teens they have acquired the base knowledge...

Small models need to have enough base knowledge to be able to be good enough -- even in a seemingly narrow regime. Where is that? Obviously they don't need all the obscure knowledge of a frontier model but there is some base level which is probably more than it would first seem.

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#17
It's terrible at hunting security bugs (I expected it to be, but I wanted to be sure). I added it to a benchmark I made with a corpus of some Mythos-discovered bugs, and it found zero. The smallest pretty successful models remain Qwen 3.6 and Gemma 4 (but I haven't tested the very small variants of those yet).

https://swelljoe.com/post/will-it-mythos/

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#18
post #7

Earlier quoted context omitted.

Can you explain this a bit more

SVG generation is a useless test, what's there more to know?

What if you're reasoning about how to generate SVG correctly?

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#19
post #9

Earlier quoted context omitted.

I think this is predicted? Part of the story is how they were able to preserve core reasoning ability while cutting knowledge like "pelicans have wings." > these findings motivate the Parametric Compression-Coverage Hypothesis, which views verifiable reasoning as compressible into compact reasoning cores, while open-domain knowledge and general-purpose competence require broad parameter coverage over facts, concepts,…

The only real essential item here is tool calling capability is it not? So I assume they tested a strong read/write/edit tool consistency?

This model doesn't support tool calling, was not part of its training. It's focused on Python (and I think C++) competitive programming and mathematics tasks, i.e. tasks with verifiable rewards. So if you have a task that fits that description, the size-to-capability ratio is good.

These kinds of models might be more useful as tools to be used by larger orchestrator models, than being the orchestrators themselves.

Re: VibeThinker: 3B param model that beats Opus 4.5 on reasoning with novel SFT+GRPO

#20
post #9

Earlier quoted context omitted.

I think this is predicted? Part of the story is how they were able to preserve core reasoning ability while cutting knowledge like "pelicans have wings." > these findings motivate the Parametric Compression-Coverage Hypothesis, which views verifiable reasoning as compressible into compact reasoning cores, while open-domain knowledge and general-purpose competence require broad parameter coverage over facts, concepts,…

The only real essential item here is tool calling capability is it not? So I assume they tested a strong read/write/edit tool consistency?

I'm not seeing any mention of tools in the paper, much less a bias towards "curiosity" to use those tools when it encounters gaps in its knowledge. So perhaps this is a good proof-of-concept that single-pass code generation is viable with this small a model - but we're still a long way from a viable solution.
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