@inproceedings{kim-etal-2026-pivot,
title = "Pivot-{SD}: Efficient Self-Distillation for Masked Diffusion Language Models",
author = "Kim, Seo Hyun and
Hong, Sunwoo and
Choi, Younwoo and
Chao, Chen-Hao and
Yun, Se-Young and
Krishnan, Rahul G",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.2146/",
pages = "48790--48806",
ISBN = "979-8-89176-459-0",
abstract = "Masked diffusion language models (dLMs) offer a promising parallel alternative to autoregressive models for complex reasoning. However, they face a unique credit-assignment challenge: reasoning failures typically stem from a few critical, early commitments that cascade downstream. Existing post-training overlooks this dynamic: supervised fine-tuning (SFT) weights all tokens uniformly, while online reinforcement learning (RL) attributes a single trajectory-level reward to every position. We introduce Pivot-SD, an efficient offline framework supervising only these high-impact bottlenecks (pivots). Pivot-SD isolates pivots using an information-gain metric measuring uncertainty reduction over the remaining masked block. It applies bidirectional supervision: successful pivots are reinforced with cross-entropy, while critical errors in failed trajectories are suppressed via targeted unlikelihood, preserving valid surrounding sub-steps. Using only 200 questions and four rollouts each, Pivot-SD improves LLaDA-8B-Instruct over full-sequence SFT and budget-matched diffusion RL baselines across math and code benchmarks."
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<abstract>Masked diffusion language models (dLMs) offer a promising parallel alternative to autoregressive models for complex reasoning. However, they face a unique credit-assignment challenge: reasoning failures typically stem from a few critical, early commitments that cascade downstream. Existing post-training overlooks this dynamic: supervised fine-tuning (SFT) weights all tokens uniformly, while online reinforcement learning (RL) attributes a single trajectory-level reward to every position. We introduce Pivot-SD, an efficient offline framework supervising only these high-impact bottlenecks (pivots). Pivot-SD isolates pivots using an information-gain metric measuring uncertainty reduction over the remaining masked block. It applies bidirectional supervision: successful pivots are reinforced with cross-entropy, while critical errors in failed trajectories are suppressed via targeted unlikelihood, preserving valid surrounding sub-steps. Using only 200 questions and four rollouts each, Pivot-SD improves LLaDA-8B-Instruct over full-sequence SFT and budget-matched diffusion RL baselines across math and code benchmarks.</abstract>
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%0 Conference Proceedings
%T Pivot-SD: Efficient Self-Distillation for Masked Diffusion Language Models
%A Kim, Seo Hyun
%A Hong, Sunwoo
%A Choi, Younwoo
%A Chao, Chen-Hao
%A Yun, Se-Young
%A Krishnan, Rahul G.
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F kim-etal-2026-pivot
%X Masked diffusion language models (dLMs) offer a promising parallel alternative to autoregressive models for complex reasoning. However, they face a unique credit-assignment challenge: reasoning failures typically stem from a few critical, early commitments that cascade downstream. Existing post-training overlooks this dynamic: supervised fine-tuning (SFT) weights all tokens uniformly, while online reinforcement learning (RL) attributes a single trajectory-level reward to every position. We introduce Pivot-SD, an efficient offline framework supervising only these high-impact bottlenecks (pivots). Pivot-SD isolates pivots using an information-gain metric measuring uncertainty reduction over the remaining masked block. It applies bidirectional supervision: successful pivots are reinforced with cross-entropy, while critical errors in failed trajectories are suppressed via targeted unlikelihood, preserving valid surrounding sub-steps. Using only 200 questions and four rollouts each, Pivot-SD improves LLaDA-8B-Instruct over full-sequence SFT and budget-matched diffusion RL baselines across math and code benchmarks.
%U https://aclanthology.org/2026.emnlp-main.2146/
%P 48790-48806
Markdown (Informal)
[Pivot-SD: Efficient Self-Distillation for Masked Diffusion Language Models](https://aclanthology.org/2026.emnlp-main.2146/) (Kim et al., EMNLP 2026)
ACL