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Comment by joaogui1 | Hacker News Reader

When we talk about tree search we allow for backtracking, so if a node has 3 children all 3 will be explored generally, or at least a subsample of the children will be, in LLM sampling you generally pick a single token/child and then just go on with that until the end of the generation.

If DeepMind is indeed doing something similar to AlphaZero to language modelling one would expect they would generate multiple "rollouts" from the current context and then use some kind of function/network to predict which next token will lead you to the best final generation and then output that token. How to do all of that using a sensible amount of compute is what remains to be seen

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Talking about efficiency. LLMs are often more efficient running batches. Sort of several lines at a time. Which means we can at some point branch new lines and run them in parallel. It will be more efficient than running one after another. More over, with some tricks we can share the 'history' instead of recomputing. This requires going deep into the model though.

What tricks are you thinking about? Sharing the history still means you need to save the state of the autoregressive transformer, which is usually prohibitively large?

I'm talking about inference. We need to save is keys, we need all of them to compute next tokens. We don't need queries. But we can play the fact that each next token depends only on the previous. And in whatever gets out of each tranformer's block it's the same. Let's call it 'history'. Which is 2d array [prev_size, embed_size]. Typical will be 1024x512 = 0.5M, may be more depending on the model, but looks like still affordable. prev_size here is [0..max_prompt_size] as we do inference. The idea is that we don't need to recompute it every time. Just add one element as we compute each next token. And if we want to try several alternative tokens, we can put them in one batch, and they will have the same 'history'. We need just a copy, or better reference. This way the branching is almost free. As opposite to 'normal' way when everything is recomputed for each alternative token.

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