Evo: Autoregressive–Diffusion Large Language Models with Evolving Balance

Junde Wu, Minhao Hu, Jiayuan Zhu, Yuyuan Liu, Tianyi Zhang, Kang Li, Jingkun Chen, Jiazhen Pan, Qirong Ho, Min Xu, Yueming Jin


Abstract
We introduce Evo, a duality latent trajectory model that bridges autoregressive (AR) and diffusion-based language generation within a continuous evolutionary generative framework. Rather than treating AR decoding and diffusion generation as separate paradigms, Evo reconceptualizes text generation as a latent flow: each token is associated with a vector-valued embedding that evolves over a progression variable, indicating its semantic maturity. Low values correspond to confident AR-like refinement, while high values invoke diffusion-style planning, allowing the model to adaptively balance AR and diffusion based on uncertainty. Theoretically, we show that both AR and diffusion models emerge as discretizations of a shared probability flow, and we derive Evo’s training objective from a unified variational ELBO. The model is implemented as a time-conditioned Transformer governed by a shared vector field, trained end-to-end to jointly infer latent codes and their progression times. During decoding, Evo performs efficient, semantics-aware refinement, achieving high-quality outputs without sacrificing speed. Empirically, Evo 8B achieves state-of-the-art or highly competitive results on 15 diverse benchmarks, including reasoning (GSM8K, ARC-C), code generation (HumanEval, MBPP), and general language understanding, while maintaining fast inference speed. Our results demonstrate that Evo delivers a new paradigm for LLM design with strong generation quality, robust symbolic reasoning, and decoding efficiency.
Anthology ID:
2026.emnlp-main.134
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:
3108–3121
Language:
URL:
https://aclanthology.org/2026.emnlp-main.134/
DOI:
Bibkey:
Cite (ACL):
Junde Wu, Minhao Hu, Jiayuan Zhu, Yuyuan Liu, Tianyi Zhang, Kang Li, Jingkun Chen, Jiazhen Pan, Qirong Ho, Min Xu, and Yueming Jin. 2026. Evo: Autoregressive–Diffusion Large Language Models with Evolving Balance. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 3108–3121, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Evo: Autoregressive–Diffusion Large Language Models with Evolving Balance (Wu et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.134.pdf