Matrix completion based on Gaussian belief propagation. - Koki Okajima; Yoshiyuki Kabashima (CoRR, 2021)

Average case analysis of Lasso under ultra sparse conditions. - Koki Okajima; Xiangming Meng; Takashi Takahashi; Yoshiyuki Kabashima (AISTATS, 2023)

On the phase diagram of extensive-rank symmetric matrix denoising beyond rotational invariance. - Jean Barbier; Francesco Camilli; Justin Ko; Koki Okajima (CoRR, 2024)

Transfer Learning in ℓ1 Regularized Regression: Hyperparameter Selection Strategy based on Sharp Asymptotic Analysis. - Koki Okajima; Tomoyuki Obuchi (Trans. Mach. Learn. Res., 2025)