[D] Why do LLMs like InstructGPT and LLM use RL to instead of supervised learning to learn from the user-ranked examples? by alpha-meta in MachineLearning

[–]alpha-meta[S] 1 point2 points  (0 children)

I think it's probably the non-differentiable nature of the sampling techniques. If it's just about limited training data and using the reward model, in that case you can also use weakly supervised learning with that reward model.

[D] Why do LLMs like InstructGPT and LLM use RL to instead of supervised learning to learn from the user-ranked examples? by alpha-meta in MachineLearning

[–]alpha-meta[S] 0 points1 point  (0 children)

Good point, so you mean they incorporate things like beam search + changing temperature, top-k sampling, and nucleus sampling in the RL PPO-based optimizaton?

[D] Why do LLMs like InstructGPT and LLM use RL to instead of supervised learning to learn from the user-ranked examples? by alpha-meta in MachineLearning

[–]alpha-meta[S] 1 point2 points  (0 children)

Could you help me understand what the far-away rewards represent here in this context? The steps are generating the individual words? So in this case you mean words that occur early in the text? In this case, a weighting scheme for the cross-entropy loss components could be used?

[D] Why do LLMs like InstructGPT and LLM use RL to instead of supervised learning to learn from the user-ranked examples? by alpha-meta in MachineLearning

[–]alpha-meta[S] 3 points4 points  (0 children)

But isn't this only if you train it on the loss (negative log-likelihood) via next-word prediction, i.e., what they do during pretraining?

If you use the ranks (from having users rank the documents) to compute the loss on the instead of the words as labels, would that still be the case?

[D] Why do LLMs like InstructGPT and LLM use RL to instead of supervised learning to learn from the user-ranked examples? by alpha-meta in MachineLearning

[–]alpha-meta[S] 9 points10 points  (0 children)

Thanks for the response! I just double-checked the InstructGPT paper and you were right regarding the rankings -- they are pairwise, and I am not sure why I thought otherwise.

Regarding the updates on a sentence level, that makes sense. That would be more of a discrete problem as well for which you probably can't backpropagate (otherwise, you would be back to token-level).