What problem does it solve? Aligning LLMs with preference data typically requires DPO's reference model, doubling memory and compute. This Skill guides SimPO training, a reference-free alternative that outperforms DPO (+6.4 points on AlpacaEval 2.0) with simpler, faster single-node training. ## Core Features & Use Cases - Reference-Free Preference Training: Configure and launch SimPO runs via HuggingFace alignment-handbook with DeepSpeed ZeRO-3, Flash Attention 2, and BF16. - Hyperparameter Guidance: Model-size-specific recommendations for beta, gamma_beta_ratio, learning rate, and SFT weight, plus troubleshooting for loss divergence, capability forgetting, and OOM. - Dataset Preparation: Preference data formats, quality filtering, dataset mixing (UltraFeedback, HH-RLHF, math preferences), and synthetic pair generation. - Use Case: Fine-tune Llama 3 8B Instruct on cleaned UltraFeedback preferences with beta 2.5 and light SFT regularization to improve alignment while preserving instruction-following capabilities. ## Quick Start Train Mistral 7B with SimPO on the UltraFeedback dataset using the alignment-handbook and DeepSpeed ZeRO-3 configuration.