collaborators

6 papers

cs.AI2026

From Sweep to Seam: Interleaved Cross-Block Post-Training Quantization

Achille Jacquemond, Yuma Ichikawa, Akira Sakai

Compressing large language models to two bits or fewer is increasingly feasible through block-wise post-training quantization; cross-block variants reconstruct neighboring Transfor…

cs.LG2026

Sign Lock-In: Randomly Initialized Weight Signs Persist and Bottleneck Sub-Bit Model Compression

Akira Sakai, Yuma Ichikawa

Sub-bit model compression targets storage below one bit per weight; as magnitudes are aggressively compressed, the sign bit becomes a fixed-cost bottleneck. Across Transformers, CN…

cs.LG2026

Signs Beat Floats: Low-Rank Double-Binary Adaptation for On-Device Fine-Tuning

Yoshihiko Fujisawa, Yuma Ichikawa, Yudai Fujimoto +2

On-device adaptation of large language models commonly keeps a quantized base model frozen while training and deploying a small, task-specific LoRA adapter. In the unmerged adapter…

cs.LG2026

PHOTON: Hierarchical Autoregressive Modeling for Lightspeed and Memory-Efficient Language Generation

Yuma Ichikawa, Naoya Takagi, Takumi Nakagawa +2

Transformers operate as horizontal token-by-token scanners; at each generation step, attending to an ever-growing sequence of token-level states. This access pattern increases pref…

cs.LG2025

More Than Bits: Multi-Envelope Double Binary Factorization for Extreme Quantization

Yuma Ichikawa, Yoshihiko Fujisawa, Yudai Fujimoto +2

For extreme low-bit quantization of large language models (LLMs), Double Binary Factorization (DBF) is attractive as it enables efficient inference without sacrificing accuracy. Ho…

stat.ML2025

LPCD: Unified Framework from Layer-Wise to Submodule Quantization

Yuma Ichikawa, Yudai Fujimoto, Akira Sakai

Post-training quantization (PTQ) aims to preserve model-level behavior; however, most methods focus on individual linear layers. Even recent extensions, such as QEP and LoaQ, which…