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Akinori F. Ebihara

5 accepted papers

2026

Accurate Evaluation of Quickest Changepoint Detectors via Non-parametric Survival Analysis

ICML 2026poster

We propose non-parametric estimators for the average run length (ARL) and average detection delay (ADD) in quickest changepoint detection (QCD) under finite and irregular sequence lengths. Although ARL and ADD are widely used as optimality criteria in theoretical and simulation studies, their applic…

Cited by 0SourceScholar
2025

Learning the Optimal Stopping for Early Classification within Finite Horizons via Sequential Probability Ratio Test

ICLR 2025poster

Time-sensitive machine learning benefits from Sequential Probability Ratio Test (SPRT), which provides an optimal stopping time for early classification of time series. However, in *finite horizon* scenarios, where input lengths are finite, determining the optimal stopping rule becomes computational…

2023

Toward Asymptotic Optimality: Sequential Unsupervised Regression of Density Ratio for Early Classification

ICASSP 2023accepted

Theoretically-inspired sequential density ratio estimation (SDRE) algorithms are proposed for the early classification of time series. Conventional SDRE algorithms can fail to estimate DRs precisely due to the internal overnormalization problem, which prevents the DR-based sequential algorithm, Sequ…

Cited by 0SourceScholar
2021

Sequential Density Ratio Estimation for Simultaneous Optimization of Speed and Accuracy

ICLR 2021spotlight

Classifying sequential data as early and as accurately as possible is a challenging yet critical problem, especially when a sampling cost is high. One algorithm that achieves this goal is the sequential probability ratio test (SPRT), which is known as Bayes-optimal: it can keep the expected number o…

2021

The Power of Log-Sum-Exp: Sequential Density Ratio Matrix Estimation for Speed-Accuracy Optimization

ICML 2021spotlight

We propose a model for multiclass classification of time series to make a prediction as early and as accurate as possible. The matrix sequential probability ratio test (MSPRT) is known to be asymptotically optimal for this setting, but contains a critical assumption that hinders broad real-world app…