Semantic Flow Regularization: Teaching LLMs to Generate Diverse Yet Coherent Responses

Kerui Peng, Li Feifei, Xingyu Fan, Que Wenhui


Abstract
When large language models are fine-tuned to generate persona- or tone-conditioned responses, their output diversity is severely limited—a failure we term Cross-Style Collapse. We trace this collapse to the cross-entropy objective, which under shared representations tends to suppress diverse continuations. We propose Semantic Flow Regularization (SFR), a lightweight auxiliary objective that supervises the backbone with continuous sentence-encoder embeddings of future segments via conditional flow matching. The stochastic flow source preserves multi-modality by construction; the flow-matching head is discarded at inference, adding zero deployment cost. On a large-scale industrial dialogue dataset (Qwen3-32B, 9 personas), SFR improves output diversity, style fidelity, and response quality over SFT. We further validate on the public LiveCodeBench-v5 (Qwen2.5-Coder-7B-Instruct), where SFR consistently improves pass@k, confirming generality beyond stylized dialogue. A controlled comparison on MBPP reveals Multi-Token Prediction to be a degenerate special case of SFR.
Anthology ID:
2026.emnlp-main.1953
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
44462–44485
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URL:
https://aclanthology.org/2026.emnlp-main.1953/
DOI:
Bibkey:
Cite (ACL):
Kerui Peng, Li Feifei, Xingyu Fan, and Que Wenhui. 2026. Semantic Flow Regularization: Teaching LLMs to Generate Diverse Yet Coherent Responses. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 44462–44485, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Semantic Flow Regularization: Teaching LLMs to Generate Diverse Yet Coherent Responses (Peng et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1953.pdf