Search Results for author: Kenji Fukumizu

Found 76 papers, 19 papers with code

State-Separated SARSA: A Practical Sequential Decision-Making Algorithm with Recovering Rewards

no code implementations18 Mar 2024 Yuto Tanimoto, Kenji Fukumizu

While many multi-armed bandit algorithms assume that rewards for all arms are constant across rounds, this assumption does not hold in many real-world scenarios.

Decision Making Q-Learning +1

Neural-Kernel Conditional Mean Embeddings

no code implementations16 Mar 2024 Eiki Shimizu, Kenji Fukumizu, Dino Sejdinovic

In conditional density estimation tasks, our NN-CME hybrid achieves competitive performance and often surpasses existing deep learning-based methods.

Density Estimation Q-Learning +1

Extended Flow Matching: a Method of Conditional Generation with Generalized Continuity Equation

no code implementations29 Feb 2024 Noboru Isobe, Masanori Koyama, Kohei Hayashi, Kenji Fukumizu

In this paper, we develop the theory of conditional generation based on Flow Matching, a current strong contender of diffusion methods.

Generalized Sobolev Transport for Probability Measures on a Graph

no code implementations7 Feb 2024 Tam Le, Truyen Nguyen, Kenji Fukumizu

In connection with the OW, we show that one only needs to simply solve a univariate optimization problem to compute the GST, unlike the complex two-level optimization problem in OW.

Document Classification Topological Data Analysis

Optimal Transport for Measures with Noisy Tree Metric

1 code implementation20 Oct 2023 Tam Le, Truyen Nguyen, Kenji Fukumizu

It is known that such OT problem (i. e., tree-Wasserstein (TW)) admits a closed-form expression, but depends fundamentally on the underlying tree structure over supports of input measures.

Document Classification Topological Data Analysis

Neural Fourier Transform: A General Approach to Equivariant Representation Learning

no code implementations29 May 2023 Masanori Koyama, Kenji Fukumizu, Kohei Hayashi, Takeru Miyato

Symmetry learning has proven to be an effective approach for extracting the hidden structure of data, with the concept of equivariance relation playing the central role.

Representation Learning

Controlling Posterior Collapse by an Inverse Lipschitz Constraint on the Decoder Network

no code implementations25 Apr 2023 Yuri Kinoshita, Kenta Oono, Kenji Fukumizu, Yuichi Yoshida, Shin-ichi Maeda

Variational autoencoders (VAEs) are one of the deep generative models that have experienced enormous success over the past decades.

Scalable Unbalanced Sobolev Transport for Measures on a Graph

1 code implementation24 Feb 2023 Tam Le, Truyen Nguyen, Kenji Fukumizu

We show that the proposed unbalanced Sobolev transport (UST) admits a closed-form formula for fast computation, and it is also negative definite.

Transfer learning with affine model transformation

1 code implementation NeurIPS 2023 Shunya Minami, Kenji Fukumizu, Yoshihiro Hayashi, Ryo Yoshida

Supervised transfer learning has received considerable attention due to its potential to boost the predictive power of machine learning in scenarios where data are scarce.

Transfer Learning

Invariance-adapted decomposition and Lasso-type contrastive learning

no code implementations13 Oct 2022 Masanori Koyama, Takeru Miyato, Kenji Fukumizu

Recent years have witnessed the effectiveness of contrastive learning in obtaining the representation of dataset that is useful in interpretation and downstream tasks.

Contrastive Learning Vocal Bursts Type Prediction

Unsupervised Learning of Equivariant Structure from Sequences

1 code implementation12 Oct 2022 Takeru Miyato, Masanori Koyama, Kenji Fukumizu

In this study, we present meta-sequential prediction (MSP), an unsupervised framework to learn the symmetry from the time sequence of length at least three.

Robust Topological Inference in the Presence of Outliers

1 code implementation3 Jun 2022 Siddharth Vishwanath, Bharath K. Sriperumbudur, Kenji Fukumizu, Satoshi Kuriki

The distance function to a compact set plays a crucial role in the paradigm of topological data analysis.

Topological Data Analysis

Invariance Learning based on Label Hierarchy

no code implementations29 Mar 2022 Shoji Toyota, Kenji Fukumizu

Invariance Learning (IL) has been developed recently to overcome this shortcoming; using training data in many domains, IL estimates such a predictor that is invariant to a change of domain.

ALGAN: Anomaly Detection by Generating Pseudo Anomalous Data via Latent Variables

no code implementations21 Feb 2022 Hironori Murase, Kenji Fukumizu

In this paper, we propose an Anomalous Latent variable Generative Adversarial Network (ALGAN) in which the GAN generator produces pseudo-anomalous data as well as fake-normal data, whereas the discriminator is trained to distinguish between normal and pseudo-anomalous data.

Anomaly Detection Generative Adversarial Network

β-Intact-VAE: Identifying and Estimating Causal Effects under Limited Overlap

no code implementations11 Oct 2021 Pengzhou Wu, Kenji Fukumizu

As an important problem in causal inference, we discuss the identification and estimation of treatment effects (TEs) under limited overlap; that is, when subjects with certain features belong to a single treatment group.

Causal Inference

Towards Principled Causal Effect Estimation by Deep Identifiable Models

no code implementations30 Sep 2021 Pengzhou Wu, Kenji Fukumizu

As an important problem in causal inference, we discuss the estimation of treatment effects (TEs).

Causal Inference

A Scaling Law for Syn-to-Real Transfer: How Much Is Your Pre-training Effective?

no code implementations29 Sep 2021 Hiroaki Mikami, Kenji Fukumizu, Shogo Murai, Shuji Suzuki, Yuta Kikuchi, Taiji Suzuki, Shin-ichi Maeda, Kohei Hayashi

Synthetic-to-real transfer learning is a framework in which a synthetically generated dataset is used to pre-train a model to improve its performance on real vision tasks.

Image Generation Transfer Learning

$\beta$-Intact-VAE: Identifying and Estimating Causal Effects under Limited Overlap

no code implementations ICLR 2022 Pengzhou Abel Wu, Kenji Fukumizu

We use a latent variable to model a prognostic score which is widely used in biostatistics and sufficient for TEs; i. e., we build a generative prognostic model.

Causal Inference

A Scaling Law for Synthetic-to-Real Transfer: How Much Is Your Pre-training Effective?

1 code implementation25 Aug 2021 Hiroaki Mikami, Kenji Fukumizu, Shogo Murai, Shuji Suzuki, Yuta Kikuchi, Taiji Suzuki, Shin-ichi Maeda, Kohei Hayashi

Synthetic-to-real transfer learning is a framework in which a synthetically generated dataset is used to pre-train a model to improve its performance on real vision tasks.

Image Generation Transfer Learning

Identifying and Estimating Causal Effects under Weak Overlap by Generative Prognostic Model

no code implementations NeurIPS 2021 Pengzhou Abel Wu, Kenji Fukumizu

As an important problem of causal inference, we discuss the identification and estimation of treatment effects (TEs) under weak overlap, i. e., subjects with certain features all belong to a single treatment group.

Causal Inference counterfactual +1

Intact-VAE: Estimating Treatment Effects under Unobserved Confounding

no code implementations17 Jan 2021 Pengzhou Wu, Kenji Fukumizu

As an important problem of causal inference, we discuss the identification and estimation of treatment effects under unobserved confounding.

Causal Inference Representation Learning

Advantage of Deep Neural Networks for Estimating Functions with Singularity on Hypersurfaces

no code implementations4 Nov 2020 Masaaki Imaizumi, Kenji Fukumizu

We develop a minimax rate analysis to describe the reason that deep neural networks (DNNs) perform better than other standard methods.

Meta Learning for Causal Direction

no code implementations6 Jul 2020 Jean-Francois Ton, Dino Sejdinovic, Kenji Fukumizu

Based on recent developments in meta learning as well as in causal inference, we introduce a novel generative model that allows distinguishing cause and effect in the small data setting.

Causal Inference Meta-Learning

Robust Persistence Diagrams using Reproducing Kernels

1 code implementation NeurIPS 2020 Siddharth Vishwanath, Kenji Fukumizu, Satoshi Kuriki, Bharath Sriperumbudur

Persistent homology has become an important tool for extracting geometric and topological features from data, whose multi-scale features are summarized in a persistence diagram.

The equivalence between Stein variational gradient descent and black-box variational inference

no code implementations ICLR Workshop DeepDiffEq 2019 Casey Chu, Kentaro Minami, Kenji Fukumizu

We formalize an equivalence between two popular methods for Bayesian inference: Stein variational gradient descent (SVGD) and black-box variational inference (BBVI).

Bayesian Inference Variational Inference

Smoothness and Stability in GANs

no code implementations ICLR 2020 Casey Chu, Kentaro Minami, Kenji Fukumizu

Generative adversarial networks, or GANs, commonly display unstable behavior during training.

Causal Mosaic: Cause-Effect Inference via Nonlinear ICA and Ensemble Method

no code implementations7 Jan 2020 Pengzhou, Wu, Kenji Fukumizu

We address the problem of distinguishing cause from effect in bivariate setting.

Exchangeable deep neural networks for set-to-set matching and learning

2 code implementations ECCV 2020 Yuki Saito, Takuma Nakamura, Hirotaka Hachiya, Kenji Fukumizu

Matching two different sets of items, called heterogeneous set-to-set matching problem, has recently received attention as a promising problem.

set matching

A Kernel Stein Test for Comparing Latent Variable Models

1 code implementation1 Jul 2019 Heishiro Kanagawa, Wittawat Jitkrittum, Lester Mackey, Kenji Fukumizu, Arthur Gretton

We propose a kernel-based nonparametric test of relative goodness of fit, where the goal is to compare two models, both of which may have unobserved latent variables, such that the marginal distribution of the observed variables is intractable.

Convex Covariate Clustering for Classification

1 code implementation5 Mar 2019 Daniel Andrade, Kenji Fukumizu, Yuzuru Okajima

Clustering, like covariate selection for classification, is an important step to compress and interpret the data.

Classification Clustering +2

Tree-Sliced Variants of Wasserstein Distances

2 code implementations NeurIPS 2019 Tam Le, Makoto Yamada, Kenji Fukumizu, Marco Cuturi

Optimal transport (\OT) theory defines a powerful set of tools to compare probability distributions.

Understanding GANs via Generalization Analysis for Disconnected Support

no code implementations27 Sep 2018 Masaaki Imaizumi, Kenji Fukumizu

This paper focuses the situation where the target probability measure satisfies the disconnected support property, which means a separate support of a probability, and relates it with the advantage of GANs.

Pointwise HSIC: A Linear-Time Kernelized Co-occurrence Norm for Sparse Linguistic Expressions

no code implementations EMNLP 2018 Sho Yokoi, Sosuke Kobayashi, Kenji Fukumizu, Jun Suzuki, Kentaro Inui

As well as deriving PMI from mutual information, we derive this new measure from the Hilbert--Schmidt independence criterion (HSIC); thus, we call the new measure the pointwise HSIC (PHSIC).

Machine Translation Sentence +2

Robust Bayesian Model Selection for Variable Clustering with the Gaussian Graphical Model

1 code implementation15 Jun 2018 Daniel Andrade, Akiko Takeda, Kenji Fukumizu

Even more severe, small insignificant partial correlations due to noise can dramatically change the clustering result when evaluating for example with the Bayesian Information Criteria (BIC).

Clustering Model Selection

Variational Learning on Aggregate Outputs with Gaussian Processes

1 code implementation NeurIPS 2018 Ho Chung Leon Law, Dino Sejdinovic, Ewan Cameron, Tim CD Lucas, Seth Flaxman, Katherine Battle, Kenji Fukumizu

While a typical supervised learning framework assumes that the inputs and the outputs are measured at the same levels of granularity, many applications, including global mapping of disease, only have access to outputs at a much coarser level than that of the inputs.

Gaussian Processes

Kernel Recursive ABC: Point Estimation with Intractable Likelihood

no code implementations ICML 2018 Takafumi Kajihara, Motonobu Kanagawa, Keisuke Yamazaki, Kenji Fukumizu

We propose a novel approach to parameter estimation for simulator-based statistical models with intractable likelihood.

Post Selection Inference with Incomplete Maximum Mean Discrepancy Estimator

no code implementations ICLR 2019 Makoto Yamada, Denny Wu, Yao-Hung Hubert Tsai, Ichiro Takeuchi, Ruslan Salakhutdinov, Kenji Fukumizu

In the paper, we propose a post selection inference (PSI) framework for divergence measure, which can select a set of statistically significant features that discriminate two distributions.

Binary Classification Change Point Detection +1

Deep Neural Networks Learn Non-Smooth Functions Effectively

no code implementations13 Feb 2018 Masaaki Imaizumi, Kenji Fukumizu

We theoretically discuss why deep neural networks (DNNs) performs better than other models in some cases by investigating statistical properties of DNNs for non-smooth functions.

Convergence Analysis of Deterministic Kernel-Based Quadrature Rules in Misspecified Settings

1 code implementation1 Sep 2017 Motonobu Kanagawa, Bharath K. Sriperumbudur, Kenji Fukumizu

This paper presents a convergence analysis of kernel-based quadrature rules in misspecified settings, focusing on deterministic quadrature in Sobolev spaces.

A Linear-Time Kernel Goodness-of-Fit Test

4 code implementations NeurIPS 2017 Wittawat Jitkrittum, Wenkai Xu, Zoltan Szabo, Kenji Fukumizu, Arthur Gretton

We propose a novel adaptive test of goodness-of-fit, with computational cost linear in the number of samples.

Influence Function and Robust Variant of Kernel Canonical Correlation Analysis

no code implementations9 May 2017 Md. Ashad Alam, Kenji Fukumizu, Yu-Ping Wang

Many unsupervised kernel methods rely on the estimation of the kernel covariance operator (kernel CO) or kernel cross-covariance operator (kernel CCO).

Learning Sparse Structural Changes in High-dimensional Markov Networks: A Review on Methodologies and Theories

no code implementations6 Jan 2017 Song Liu, Kenji Fukumizu, Taiji Suzuki

Recent years have seen an increasing popularity of learning the sparse \emph{changes} in Markov Networks.

Post Selection Inference with Kernels

no code implementations12 Oct 2016 Makoto Yamada, Yuta Umezu, Kenji Fukumizu, Ichiro Takeuchi

We propose a novel kernel based post selection inference (PSI) algorithm, which can not only handle non-linearity in data but also structured output such as multi-dimensional and multi-label outputs.

General Classification Multi-class Classification

Kernel Mean Embedding of Distributions: A Review and Beyond

no code implementations31 May 2016 Krikamol Muandet, Kenji Fukumizu, Bharath Sriperumbudur, Bernhard Schölkopf

Next, we discuss the Hilbert space embedding for conditional distributions, give theoretical insights, and review some applications.

Causal Discovery Two-sample testing

Convergence guarantees for kernel-based quadrature rules in misspecified settings

no code implementations NeurIPS 2016 Motonobu Kanagawa, Bharath K. Sriperumbudur, Kenji Fukumizu

Kernel-based quadrature rules are becoming important in machine learning and statistics, as they achieve super-$\sqrt{n}$ convergence rates in numerical integration, and thus provide alternatives to Monte Carlo integration in challenging settings where integrands are expensive to evaluate or where integrands are high dimensional.

Numerical Integration

Robust Kernel (Cross-) Covariance Operators in Reproducing Kernel Hilbert Space toward Kernel Methods

no code implementations17 Feb 2016 Md. Ashad Alam, Kenji Fukumizu, Yu-Ping Wang

Finally, we propose a method based on robust kernel CO and robust kernel CCO, called robust kernel CCA, which is designed for contaminated data and less sensitive to noise than classical kernel CCA.

Persistence weighted Gaussian kernel for topological data analysis

2 code implementations8 Jan 2016 Genki Kusano, Kenji Fukumizu, Yasuaki Hiraoka

Topological data analysis (TDA) is an emerging mathematical concept for characterizing shapes in complex data.

Algebraic Topology

Structure Learning of Partitioned Markov Networks

no code implementations2 Apr 2015 Song Liu, Taiji Suzuki, Masashi Sugiyama, Kenji Fukumizu

We learn the structure of a Markov Network between two groups of random variables from joint observations.

Time Series Time Series Analysis

Model-based Kernel Sum Rule: Kernel Bayesian Inference with Probabilistic Models

no code implementations18 Sep 2014 Yu Nishiyama, Motonobu Kanagawa, Arthur Gretton, Kenji Fukumizu

Our contribution in this paper is to introduce a novel approach, termed the {\em model-based kernel sum rule} (Mb-KSR), to combine a probabilistic model and kernel Bayesian inference.

Bayesian Inference

Kernel-based Information Criterion

no code implementations25 Aug 2014 Somayeh Danafar, Kenji Fukumizu, Faustino Gomez

This paper introduces Kernel-based Information Criterion (KIC) for model selection in regression analysis.

GPR Model Selection +1

Kernel Mean Shrinkage Estimators

no code implementations21 May 2014 Krikamol Muandet, Bharath Sriperumbudur, Kenji Fukumizu, Arthur Gretton, Bernhard Schölkopf

A mean function in a reproducing kernel Hilbert space (RKHS), or a kernel mean, is central to kernel methods in that it is used by many classical algorithms such as kernel principal component analysis, and it also forms the core inference step of modern kernel methods that rely on embedding probability distributions in RKHSs.

Characteristic Kernels and Infinitely Divisible Distributions

no code implementations28 Mar 2014 Yu Nishiyama, Kenji Fukumizu

If $P, Q$, and kernel $k$ are Gaussians, then computation (i) and (ii) results in Gaussian pdfs that is tractable.

Filtering with State-Observation Examples via Kernel Monte Carlo Filter

no code implementations17 Dec 2013 Motonobu Kanagawa, Yu Nishiyama, Arthur Gretton, Kenji Fukumizu

In particular, the sampling and resampling procedures are novel in being expressed using kernel mean embeddings, so we theoretically analyze their behaviors.

Density Estimation in Infinite Dimensional Exponential Families

1 code implementation12 Dec 2013 Bharath Sriperumbudur, Kenji Fukumizu, Arthur Gretton, Aapo Hyvärinen, Revant Kumar

When $p_0\in\mathcal{P}$, we show that the proposed estimator is consistent, and provide a convergence rate of $n^{-\min\left\{\frac{2}{3},\frac{2\beta+1}{2\beta+2}\right\}}$ in Fisher divergence under the smoothness assumption that $\log p_0\in\mathcal{R}(C^\beta)$ for some $\beta\ge 0$, where $C$ is a certain Hilbert-Schmidt operator on $H$ and $\mathcal{R}(C^\beta)$ denotes the image of $C^\beta$.

Density Estimation

Kernel Mean Estimation and Stein's Effect

no code implementations4 Jun 2013 Krikamol Muandet, Kenji Fukumizu, Bharath Sriperumbudur, Arthur Gretton, Bernhard Schölkopf

A mean function in reproducing kernel Hilbert space, or a kernel mean, is an important part of many applications ranging from kernel principal component analysis to Hilbert-space embedding of distributions.

Gradient-based kernel method for feature extraction and variable selection

no code implementations NeurIPS 2012 Kenji Fukumizu, Chenlei Leng

We propose a novel kernel approach to dimension reduction for supervised learning: feature extraction and variable selection; the former constructs a small number of features from predictors, and the latter finds a subset of predictors.

Dimensionality Reduction Variable Selection

Equivalence of distance-based and RKHS-based statistics in hypothesis testing

no code implementations25 Jul 2012 Dino Sejdinovic, Bharath Sriperumbudur, Arthur Gretton, Kenji Fukumizu

We provide a unifying framework linking two classes of statistics used in two-sample and independence testing: on the one hand, the energy distances and distance covariances from the statistics literature; on the other, maximum mean discrepancies (MMD), that is, distances between embeddings of distributions to reproducing kernel Hilbert spaces (RKHS), as established in machine learning.

Two-sample testing

Kernel Bayes' Rule

no code implementations NeurIPS 2011 Kenji Fukumizu, Le Song, Arthur Gretton

A nonparametric kernel-based method for realizing Bayes' rule is proposed, based on kernel representations of probabilities in reproducing kernel Hilbert spaces.

Bayesian Inference

Learning in Hilbert vs. Banach Spaces: A Measure Embedding Viewpoint

no code implementations NeurIPS 2011 Kenji Fukumizu, Gert R. Lanckriet, Bharath K. Sriperumbudur

The goal of this paper is to investigate the advantages and disadvantages of learning in Banach spaces over Hilbert spaces.

A Fast, Consistent Kernel Two-Sample Test

no code implementations NeurIPS 2009 Arthur Gretton, Kenji Fukumizu, Zaïd Harchaoui, Bharath K. Sriperumbudur

A kernel embedding of probability distributions into reproducing kernel Hilbert spaces (RKHS) has recently been proposed, which allows the comparison of two probability measures P and Q based on the distance between their respective embeddings: for a sufficiently rich RKHS, this distance is zero if and only if P and Q coincide.

Vocal Bursts Valence Prediction

Graph Zeta Function in the Bethe Free Energy and Loopy Belief Propagation

no code implementations NeurIPS 2009 Yusuke Watanabe, Kenji Fukumizu

We also propose a new approach to the uniqueness of LBP fixed point, and show various conditions of uniqueness.

Hilbert space embeddings and metrics on probability measures

no code implementations30 Jul 2009 Bharath K. Sriperumbudur, Arthur Gretton, Kenji Fukumizu, Bernhard Schölkopf, Gert R. G. Lanckriet

First, we consider the question of determining the conditions on the kernel $k$ for which $\gamma_k$ is a metric: such $k$ are denoted {\em characteristic kernels}.

Dimensionality Reduction

On integral probability metrics, φ-divergences and binary classification

no code implementations18 Jan 2009 Bharath K. Sriperumbudur, Kenji Fukumizu, Arthur Gretton, Bernhard Schölkopf, Gert R. G. Lanckriet

First, to understand the relation between IPMs and $\phi$-divergences, the necessary and sufficient conditions under which these classes intersect are derived: the total variation distance is shown to be the only non-trivial $\phi$-divergence that is also an IPM.

Information Theory Information Theory

Characteristic Kernels on Groups and Semigroups

no code implementations NeurIPS 2008 Kenji Fukumizu, Arthur Gretton, Bernhard Schölkopf, Bharath K. Sriperumbudur

Embeddings of random variables in reproducing kernel Hilbert spaces (RKHSs) may be used to conduct statistical inference based on higher order moments.

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