I implemented DPO from the paper and the reward margin hit 599 here's what that actually means [R]

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DPO (Rafailov et al., NeurIPS 2023) is supposed to be the clean alternative to PPO. No reward model in the training loop, no value function, no rollout collection. Just a binary cross-entropy loss over preference pairs. And the math is elegant the partition function Z(x) cancels out when you substitute the log-ratio reparameterisation into the Bradley-Terry model. I implemented it from scratch as part of a multi-stage RLHF project (same model, same tokenizer, same evaluation suite as my PPO a...