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arxiv 2405.14734 v3 pith:FJGVIXSB submitted 2024-05-23 cs.CL cs.LG

SimPO: Simple Preference Optimization with a Reference-Free Reward

classification cs.CL cs.LG
keywords simporewardalpacaevalarena-hardmodeloptimizationpreferencealgorithm
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Direct Preference Optimization (DPO) is a widely used offline preference optimization algorithm that reparameterizes reward functions in reinforcement learning from human feedback (RLHF) to enhance simplicity and training stability. In this work, we propose SimPO, a simpler yet more effective approach. The effectiveness of SimPO is attributed to a key design: using the average log probability of a sequence as the implicit reward. This reward formulation better aligns with model generation and eliminates the need for a reference model, making it more compute and memory efficient. Additionally, we introduce a target reward margin to the Bradley-Terry objective to encourage a larger margin between the winning and losing responses, further improving the algorithm's performance. We compare SimPO to DPO and its latest variants across various state-of-the-art training setups, including both base and instruction-tuned models such as Mistral, Llama 3, and Gemma 2. We evaluate on extensive chat-based evaluation benchmarks, including AlpacaEval 2, MT-Bench, and Arena-Hard. Our results demonstrate that SimPO consistently and significantly outperforms existing approaches without substantially increasing response length. Specifically, SimPO outperforms DPO by up to 6.4 points on AlpacaEval 2 and by up to 7.5 points on Arena-Hard. Our top-performing model, built on Gemma-2-9B-it, achieves a 72.4% length-controlled win rate on AlpacaEval 2, a 59.1% win rate on Arena-Hard, and ranks 1st on Chatbot Arena among <10B models with real user votes.

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Cited by 28 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. CrossVLA: Cross-Paradigm Post-Training and Inference Optimization for Vision-Language-Action Models

    cs.CV 2026-05 unverdicted novelty 7.0

    CrossVLA develops a surrogate log-probability estimator for DPO on flow-matching VLAs, shows DoRA outperforming LoRA by +10.4 pp mean on LIBERO, and identifies inference bottlenecks with limited caching gains.

  2. CrossVLA: Cross-Paradigm Post-Training and Inference Optimization for Vision-Language-Action Models

    cs.CV 2026-05 conditional novelty 7.0

    CrossVLA introduces a surrogate log-probability estimator to enable DPO on flow-matching VLAs, reports DoRA yielding +10.4 pp mean gains over SFT on LIBERO with 600 trials, and shows inference caching limited to 21% s...

  3. DDO-RM: Distribution-Level Policy Improvement after Reward Learning

    stat.ML 2026-04 unverdicted novelty 7.0

    DDO-RM turns reward scores into a target distribution and applies KL-regularized mirror-descent projection on finite candidates to improve policies, outperforming DPO on Pythia-410M.

  4. Magpie: Alignment Data Synthesis from Scratch by Prompting Aligned LLMs with Nothing

    cs.CL 2024-06 unverdicted novelty 7.0

    Magpie synthesizes 300K high-quality alignment instructions from Llama-3-Instruct via auto-regressive prompting on partial templates, enabling fine-tuned models to match official instruct performance on AlpacaEval, Ar...

  5. Black-box, Adaptive, Efficient, Transferable, Harmful, Applicable... Attacks Are All You Need to Break LLMs

    cs.CR 2026-06 unverdicted novelty 6.0

    IHO is a new black-box jailbreak attack for LLMs that is adaptive, efficient, transferable across models and behaviors, and effective even against layered defenses without modification.

  6. AdaDPO: Self-Adaptive Direct Preference Optimization with Balanced Gradient Updates

    cs.CL 2026-05 unverdicted novelty 6.0

    AdaDPO uses self-adaptive stop-gradient coefficients to balance preferred and dispreferred gradients in DPO, achieving higher AlpacaEval 2 win rates than standard DPO on Llama-3-8B-Instruct.

  7. DEFLECT: Delay-Robust Execution via Flow-matching Likelihood-Estimated Counterfactual Tuning for VLA Policies

    cs.RO 2026-05 unverdicted novelty 6.0

    DEFLECT is an offline post-training method that improves async VLA policy success rates under high inference delays by using flow-matching likelihood ratios on counterfactual fresh/stale action pairs from a frozen ref...

  8. Vocabulary Hijacking in LVLMs: Unveiling Critical Attention Heads by Excluding Inert Tokens to Mitigate Hallucination

    cs.MM 2026-05 unverdicted novelty 6.0

    LVLMs show vocabulary hijacking by inert tokens that decode to hijacking anchors; HABI locates them, NHAR finds resilient heads, and HAVAE boosts those heads to cut hallucinations.

  9. Mechanistic Analysis of Alignment Algorithms in Language Models

    cs.LG 2026-05 unverdicted novelty 6.0

    Mechanistic analysis of six preference optimization methods reveals distinct geometric shifts in model representations, with KTO/GRPO enhancing separability while DPO/ORPO degrade it.

  10. Beyond Pairs: Your Language Model is Secretly Optimizing a Preference Graph

    cs.LG 2026-05 unverdicted novelty 6.0

    GraphDPO generalizes pairwise DPO to a graph-structured Plackett-Luce objective over DAGs induced by rollout rankings, enforcing transitivity with linear complexity and recovering DPO as a special case.

  11. RLearner-LLM: Balancing Logical Grounding and Fluency in Large Language Models via Hybrid Direct Preference Optimization

    cs.CL 2026-05 unverdicted novelty 6.0

    RLearner-LLM achieves up to 6x gains in NLI entailment over standard fine-tuning by using an automated hybrid DPO pipeline that balances logic and fluency across multiple model sizes and domains.

  12. RLearner-LLM: Balancing Logical Grounding and Fluency in Large Language Models via Hybrid Direct Preference Optimization

    cs.CL 2026-05 unverdicted novelty 6.0

    RLearner-LLM's Hybrid-DPO fuses DeBERTa NLI and LLM verifier scores to deliver up to 6x higher NLI entailment than standard SFT while preserving answer coverage across academic domains.

  13. Bayesian Rate Inference for Sequence Motif Dynamics in Systems of Reactive Nucleic Acids

    physics.bio-ph 2026-04 unverdicted novelty 6.0

    A Bayesian method infers reaction rate parameters for sequence motifs in RNA systems from simulation ligation data.

  14. Representation-Guided Parameter-Efficient LLM Unlearning

    cs.CL 2026-04 unverdicted novelty 6.0

    REGLU guides LoRA-based unlearning via representation subspaces and orthogonal regularization to outperform prior methods on forget-retain trade-off in LLM benchmarks.

  15. The Differences Between Direct Alignment Algorithms are a Blur

    cs.LG 2025-02 unverdicted novelty 6.0

    A controlled unification of direct alignment algorithms shows the ranking objective (pairwise vs pointwise) drives alignment quality more than the scalar score optimized.

  16. Preference Goal Tuning: Post-Training as Latent Control for Frozen Policies

    cs.AI 2024-12 unverdicted novelty 6.0

    PGT optimizes latent goal embeddings for frozen policies via trajectory-level preference objectives, reporting 72-81.6% relative gains on 17 Minecraft tasks and 13.4% better OOD performance than fine-tuning.

  17. DataComp-LM: In search of the next generation of training sets for language models

    cs.LG 2024-06 unverdicted novelty 6.0

    DCLM-Baseline dataset lets a 7B model reach 64% 5-shot MMLU accuracy after 2.6T tokens, beating prior open-data models by 6.6 points on MMLU with 40% less compute.

  18. RLearner-LLM: Balancing Logical Grounding and Fluency in Large Language Models via Hybrid Direct Preference Optimization

    cs.CL 2026-05 unverdicted novelty 5.0

    Hybrid-DPO combining NLI and verifier scores delivers up to 6x NLI improvement over SFT baselines across multiple LLMs and domains while preserving answer coverage and inference speed.

  19. Bayesian Rate Inference for Sequence Motif Dynamics in Systems of Reactive Nucleic Acids

    physics.bio-ph 2026-04 unverdicted novelty 5.0

    A Bayesian inference framework is presented to infer parameters of motif rate equations from ligation count data generated by strand reactor simulations in reactive nucleic acid systems.

  20. Failure Modes of Maximum Entropy RLHF

    cs.LG 2025-09 unverdicted novelty 5.0

    Derives SimPO from MaxEnt RL and reports that MaxEnt RL in online RLHF exhibits frequent overoptimization and unstable KL dynamics across scales, unlike stable KL-constrained baselines.

  21. Difficulty-Based Preference Data Selection by DPO Implicit Reward Gap

    cs.CL 2025-08 unverdicted novelty 5.0

    Selecting preference pairs whose DPO implicit reward gap is small yields better LLM alignment than random or baseline selection while using only 10% of the data.

  22. InfluMatch: Frontier-Quality KOL Search at 4B-Model Cost

    cs.CL 2026-07 conditional novelty 4.0

    A 4B-model cascade for Thai KOL matching reaches 94.1% P@5 on 11 queries, matching a frontier model, with pairwise SimPO training transferring end-to-end while pointwise SFT+GRPO does not.

  23. BV-Blend: Uncertainty-Weighted Historical Baselines for Stable Critic-Free RL with Verifiable Rewards

    cs.AI 2026-06 unverdicted novelty 4.0

    BV-Blend blends prompt-local and semantic-cluster historical reward statistics via SEM-derived weights to stabilize critic-free RL advantage estimation.

  24. Can AI Be a Good Peer Reviewer? A Survey of Peer Review Process, Evaluation, and the Future

    cs.CL 2026-04 unverdicted novelty 4.0

    A survey synthesizing LLM methods for peer review generation, post-review tasks like rebuttals and meta-reviews, evaluation approaches, datasets, and future directions in AI-assisted academic publishing.

  25. Backtranslation Augmented Direct Preference Optimization for Neural Machine Translation

    cs.CL 2026-04 unverdicted novelty 4.0

    DPO post-training with backtranslation augmentation raises COMET score from 0.703 to 0.747 for English-to-German translation on the gemma3-1b model.

  26. Backtranslation Augmented Direct Preference Optimization for Neural Machine Translation

    cs.CL 2026-04 unverdicted novelty 4.0

    DPO with backtranslation post-training raises English-to-German COMET from 0.703 to 0.747 on gemma3-1b.

  27. The Hitchhiker's Guide to Agentic AI: From Foundations to Systems

    cs.AI 2026-06 unverdicted novelty 2.0

    A comprehensive reference book organizing existing techniques for agentic AI systems across LLM substrate, reasoning, agent design patterns, inter-agent coordination, and production deployment.

  28. Bridging Brains and Machines: A Unified Frontier in Neuroscience, Artificial Intelligence, and Neuromorphic Systems

    q-bio.NC 2025-07 unverdicted novelty 2.0

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