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Ochanomizu University

Academic institutionasia · jp
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Research library3linked papers
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Selected work

Representative Papers

Stabilizing Private LASSO under Heterogeneous Covariates via Anisotropic Objective Perturbation

May 02, 2026

This work addresses the instability of objective perturbation in high-dimensional LASSO under differential privacy, which arises from heterogeneity in covariate scales and compromises both estimation accuracy and privacy guarantees. The authors propose an anisotropic objective perturbation method based on the Gram matrix, employing a “pre-distortion” strategy to counteract perturbation distortions induced by covariate structure and thereby restore isotropy in the estimation process. Notably, this approach directly incorporates structural information of the covariates into the perturbation mechanism, eliminating the need for privacy-budget-consuming data preprocessing. By integrating the algorithm within an approximate message passing (AMP) framework and leveraging state evolution analysis, the method achieves significantly improved convergence stability, statistical efficiency, and privacy performance while maintaining rigorous differential privacy guarantees.

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Meta Theorem for Hardness on FCP-Problem

Apr 16, 2025

This paper addresses the computational complexity of the Fewest Clues Problem (FCP) variant for NP-complete problems, specifically asking whether the FCP variant of every NP-complete problem is Σ₂^p-complete—a long-standing open question, previously resolved only for isolated cases. Method: We introduce the first general metatheorem that characterizes sufficient structural conditions for Σ₂^p-completeness of FCP variants, integrating polynomial-time reductions, second-order Boolean logic modeling, and constructive Σ₂^p-completeness techniques. Contribution/Results: We rigorously establish Σ₂^p-completeness for the FCP variants of canonical NP-complete problems—including SAT and Vertex Cover—and derive a reusable hardness certification framework. This resolves the open problem in full generality, providing both a foundational theoretical basis and practical tools for future analysis of FCP variants.

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Latest Papers

Stabilizing Private LASSO under Heterogeneous Covariates via Anisotropic Objective Perturbation

May 02, 2026

This work addresses the instability of objective perturbation in high-dimensional LASSO under differential privacy, which arises from heterogeneity in covariate scales and compromises both estimation accuracy and privacy guarantees. The authors propose an anisotropic objective perturbation method based on the Gram matrix, employing a “pre-distortion” strategy to counteract perturbation distortions induced by covariate structure and thereby restore isotropy in the estimation process. Notably, this approach directly incorporates structural information of the covariates into the perturbation mechanism, eliminating the need for privacy-budget-consuming data preprocessing. By integrating the algorithm within an approximate message passing (AMP) framework and leveraging state evolution analysis, the method achieves significantly improved convergence stability, statistical efficiency, and privacy performance while maintaining rigorous differential privacy guarantees.

0 citationsRead paper

Meta Theorem for Hardness on FCP-Problem

Apr 16, 2025

This paper addresses the computational complexity of the Fewest Clues Problem (FCP) variant for NP-complete problems, specifically asking whether the FCP variant of every NP-complete problem is Σ₂^p-complete—a long-standing open question, previously resolved only for isolated cases. Method: We introduce the first general metatheorem that characterizes sufficient structural conditions for Σ₂^p-completeness of FCP variants, integrating polynomial-time reductions, second-order Boolean logic modeling, and constructive Σ₂^p-completeness techniques. Contribution/Results: We rigorously establish Σ₂^p-completeness for the FCP variants of canonical NP-complete problems—including SAT and Vertex Cover—and derive a reusable hardness certification framework. This resolves the open problem in full generality, providing both a foundational theoretical basis and practical tools for future analysis of FCP variants.

0 citationsRead paper