What problem does it solve? Aligning LLMs to human preferences with DPO or PPO requires a reference model or reward model, adding memory overhead and training complexity. This Skill guides SimPO training, a reference-free preference optimization method that outperforms DPO (+6.4 points on AlpacaEval 2.0) with simpler, more efficient single-node training. ## Core Features & Use Cases - Reference-Free Preference Training: Train on chosen/rejected preference pairs without loading a reference model, using the HuggingFace alignment-handbook with DeepSpeed ZeRO-3. - Hyperparameter Guidance: Provides recommended beta, gamma_beta_ratio, learning rate, and sft_weight values per model size (7B to 70B) and task type (chat, math, code). - Dataset & Troubleshooting References: Covers preference dataset formats, quality filtering, loss function selection (sigmoid vs hinge), and fixes for loss divergence, capability forgetting, and OOM. - Use Case: Fine-tune Mistral 7B on UltraFeedback preference data with a single accelerate launch command, or align Llama 3 8B Instruct on math preferences with SFT regularization to preserve capabilities. ## Quick Start Train Mistral 7B with SimPO on the UltraFeedback dataset using the provided YAML config and accelerate launch with DeepSpeed ZeRO-3.