Papers by Sangwoo Kang
CPC-GRPO: Answer-Free Reinforcement Learning with Cross-Prompt Consensus Rewards (2026.findings-acl)
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| Challenge: | Reinforcement learning with verifiable rewards is a popular post-training tool for large language models, but relies on a ground-truth answer or external verifier, which limits applicability and increases cost. |
| Approach: | They propose an answer-free training objective that derives rewards solely from the model’s own probabilities by exploiting prompt paraphrases as multiple semantic views of the same intent. |
| Outcome: | The proposed objective derives rewards solely from the model’s own probabilities by exploiting prompt paraphrases as multiple semantic views of the same intent. |
Exploration-Driven Reinforcement Learning for Expert Routing Improvement in Mixture-of-Experts Language Models (2025.findings-emnlp)
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| Challenge: | MoE-based LLMs are not explicitly supervised to select suitable experts. |
| Approach: | They propose Exploration-Driven Reinforcement Learning (ERL) which explicitly optimizes the router by exploration of alternative routing paths. |
| Outcome: | The proposed method improves summarization (SAMSum, XSUM, question answering, and language modeling), and raises routing quality, delivering 8.9 higher MRR than baselines over 100 perturbed routing paths. |
TA-GRPO-d: Trajectory-Aware GRPO for Optimizing Denoising Trajectories in Diffusion LLMs (2026.acl-long)
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| Challenge: | Existing dLLMs rely on fixed denoising schedules and cannot learn efficient unmasking orders. |
| Approach: | They propose a framework that transforms dLLM decoding into a trajectory-aware policy . it uses a confidence-gated denoising strategy that decides which tokens to unmask . |
| Outcome: | The proposed model can learn which tokens to unmask and how many to unmak per step . it can learn the output quality and efficiency of the decoding path itself . |
FractalLLM: Lossless Self-Speculative Decoding with Layer Embedded Self-Compression (2025.findings-emnlp)
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| Challenge: | Autoregressive decoding requires a full forward pass for each generated token, increasing inference latency. |
| Approach: | They propose a lossless self-speculative decoding method that embeds a compressed model within selected decoder layers of the original model. |
| Outcome: | The proposed method achieves substantial speed-ups (up to 2.47) over standard autoregressive decoding. |
AG-GRPO: Answer-Guided GRPO for Masked Diffusion Language Models (2026.acl-long)
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| Challenge: | Recent work on large language models (LLMs) has emphasized not only final-answer accuracy but also reliability of reasoning on challenging tasks. |
| Approach: | They propose an answer-guided group-relative policy optimization for masked diffusion language models which generates text through iterative mangled token restoration. |
| Outcome: | The proposed approach improves over pretrained dLLMs and prior RL methods across mathematics, puzzle-solving, and code-generation benchmarks. |