collaborators

5 papers

cs.LG2026

Why and When Deep is Better than Shallow: Implementation-Agnostic State-Transition Model of Deep Learning

Sho Sonoda, Yuka Hashimoto, Isao Ishikawa +1

Why and when does depth improve generalization? We study this question in an implementation-agnostic state-transition model, where a depth- predictor is a readout class comp…

cs.LG2026

Why High-rank Neural Networks Generalize?: An Algebraic Framework with RKHSs

Yuka Hashimoto, Sho Sonoda, Isao Ishikawa +1

We derive a new Rademacher complexity bound for deep neural networks using Koopman operators, group representations, and reproducing kernel Hilbert spaces (RKHSs). The proposed bou…

math.DS2025

Koopman operators with intrinsic observables in rigged reproducing kernel Hilbert spaces

Isao Ishikawa, Yuka Hashimoto, Masahiro Ikeda +1

This paper presents a novel approach for estimating the Koopman operator defined on a reproducing kernel Hilbert space (RKHS) and its spectra. We propose an estimation method, what…

math.DS2025

A Data-Driven Framework for Koopman Semigroup Estimation in Stochastic Dynamical Systems

Yuanchao Xu, Kaidi Shao, Isao Ishikawa +3

We present Stochastic Dynamic Mode Decomposition (SDMD), a novel data-driven framework for approximating the Koopman semigroup in stochastic dynamical systems. Unlike existing meth…

cs.LG2025

Deep Ridgelet Transform and Unified Universality Theorem for Deep and Shallow Joint-Group-Equivariant Machines

Sho Sonoda, Yuka Hashimoto, Isao Ishikawa +1

We present a constructive universal approximation theorem for learning machines equipped with joint-group-equivariant feature maps, called the joint-equivariant machines, based on…