What problem does it solve?
SimPO addresses the need to align LLM behavior using chosen/rejected preference pairs while avoiding the complexity and extra compute of reference-model-based methods like DPO.
Core Features & Use Cases
- Reference-free preference optimization: Trains directly from (prompt, chosen, rejected) pairs without requiring a separate reference model.
- Efficient DPO alternative: Uses SimPO’s optimized objective to achieve strong preference separation with fewer forward-pass requirements.
- Control alignment strength: Tunes key hyperparameters such as beta and gamma/beta to adjust margin and alignment aggressiveness.
Use case example: You have preference data for instruction following (chosen/rejected responses) and want to fine-tune a 7B or 8B model for better preference alignment using a simpler, faster workflow than DPO.
Quick Start
Use the simpo-training skill to train your model on preference pairs by supplying your target model, dataset_mixer, and SimPO hyperparameters from the provided configuration examples.