Nathan Lambert: belief

Transcript context

…We haven’t really mentioned it much, but implied in this discussion is context length as well. Is there a lot of innovations that’s possible there? I think the colloquially accepted thing is that it’s a compute and data problem. Sometimes there are small architecture things, like attention variants. We talked about hybrid attention models, which is essentially if you have what looks like a state space model within your transformer. Those are better suited because you have to spend less compute to model the furthest along token. But those aren’t free because they have to be accompanied by a lot of compute or the right data. How many sequences of 100,000 tokens do you have in the world, and where do you get these? It just ends up being pretty expensive to scale them. So we’ve gotten pretty quickly to a million tokens of input context length. And I would expect it to keep increasing and get to 2 million or 5 million this year, but I don’t expect it to go to, like, 100 million. That would be a true breakthrough, and I think those breakthroughs are possible. I think of the continual learning thing as a research problem where there could be a breakthrough that makes transformers work way better at this and it’s cheap. These things could happen with so much scientific attention. Но turning the crank, it’ll be consistent increases over time. I think also looking at the extremes, there’s no free lunch. One extreme to make it cheap is to have, let’s say, an RNN that has a single state where you save everything from the previous stuff. It’s a specific fixed-size thing, so you never really grow the memory. You are stuffing everything into one state, but then the longer the context gets, the more information you forget because you can’t compress everything into one state. Then on the other hand, you have the transformers, which try to remember every token. That is great if you want to look up specific information, but very expensive because you have the KV cache and the dot product that grow. But then, like you said, the Mamba layers kind of have the same problem. Like an RNN, you try to compress everything into one state, and you’re a bit more selective there. I think it’s like this Goldilocks zone again with NVIDIA Nemotron 3; they found a good ratio of how many attention layers you need for the global information where everything is accessible compared to having these compressed states. I think we will scale more by finding better ratios in that Goldilocks zone between making it cheap enough to run and making it powerful enough to be useful. And one more plug here: the recursive language model paper is one of the papers that tries to address the long context thing. What they found is, essentially, instead of stuffing everything into this long context, if you break it up into multiple smaller tasks, you save memory and can actually get better accuracy than having the LLM try everything all at once. It’s a new paradigm; we will see if there are other flavors of that. I think we will still make improvement on long context, but like Nathan said, the problem is for pre-training itself, we don’t have as many long-context documents as other documents. So it’s harder to study basically how LMs behave on that level.…

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