Updated on 2026/03/19

写真a

 
TUJI HIROSHI
 
Organization
School of Science Assistant Professor
Title
Assistant Professor
Contact information
メールアドレス
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Research Areas

  • Natural Science / Geometry  / Geometric Analysis, Convex Geometry, Functional Analysis

Education

  • Department of Mathematics, Graduate School of Science, Osaka University, doctoral course

    2020.4 - 2023.3

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  • Department of Mathematics, Graduate School of Science, Osaka University, master's course

    2018.4 - 2020.3

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Research History

  • Institute of Science Tokyo   Department of Mathematics

    2025.10

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  • Department of Mathematics, Saitama University   JSPS research fellow (PD)

    2024.4 - 2025.9

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  • Department of Mathematics, Graduate School of Science, Osaka University   JSPS Research Fellow PD

    2023.4 - 2024.3

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  • Department of Mathematics, Graduate School of Science, Osaka University   JSPS Research Fellow DC2

    2022.4 - 2023.3

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Papers

  • The Gaussian Conjugate Rogers-Shephard Inequality

    Emanuel Milman, Shohei Nakamura, Hiroshi Tsuji

    2026.2

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    We fuse between the Rogers-Shephard inequality for the Lebesgue measure and Royen's Gaussian Correlation Inequality, simultaneously extending both into a single sharp inequality for the Gaussian measure $γ$ on $\mathbb{R}^n$, stating that \[ γ(K) γ(L) \leq γ(K\cap L) γ(K+L) \] whenever $K$ and $L$ are origin-symmetric convex sets in $\mathbb{R}^n$. This confirms a conjecture of M. Tehranchi [https://doi.org/10.1214/17-ECP89]. In fact, we show that the inequality remains valid whenever the Gaussian barycenters of $K$ and $L$ are at the origin, and characterize the equality cases. After rescaling, this also yields the following new inequality for convex sets with (Lebesgue) barycenters at the origin: \[ |K| |L| \leq |K \cap L| |K + L | ; \] this can be seen as a conjugate counterpart to Spingarn's extension of the Rogers-Shephard inequality (where $K+L$ is replaced by $K-L$ above). We also derive an additional conjugate version of a Gaussian inequality due to V. Milman and Pajor, as well as several extensions. Our main tool is a new Gaussian Forward-Reverse Brascamp-Lieb inequality for centered log-concave functions, of independent interest, which is crucially applicable to degenerate Gaussian covariances.

    arXiv

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    Other Link: https://arxiv.org/pdf/2602.07981v1

  • A generalized Legendre duality relation and Gaussian saturation Reviewed

    Shohei Nakamura, Hiroshi Tsuji

    Inventiones mathematicae   2025.10

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    Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    Abstract

    Motivated by the barycenter problem in optimal transportation theory, Kolesnikov–Werner recently extended the concept of the Legendre duality relation from two functions to multiple functions. We further generalize this duality relation and then establish the centered Gaussian saturation property for a Blaschke–Santaló-type inequality associated with it. Our approach to understanding this generalized Legendre duality relation is based on the observation that directly links Legendre duality with the inverse Brascamp–Lieb inequality. More precisely, for a large family of degenerate Brascamp–Lieb data, we prove that the centered Gaussian saturation property for the inverse Brascamp–Lieb inequality holds when inputs are restricted to even and log-concave functions. As an application to convex geometry, we establish a significant case of a conjecture by Kolesnikov–Werner concerning the Blaschke–Santaló inequality for multiple even functions and multiple symmetric convex bodies. Furthermore, in the context of information theory and optimal transportation theory, this provides an affirmative answer to another conjecture by Kolesnikov–Werner concerning a Talagrand-type inequality for multiple even probability measures involving the Wasserstein barycenter.

    DOI: 10.1007/s00222-025-01382-5

    arXiv

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    Other Link: https://link.springer.com/article/10.1007/s00222-025-01382-5/fulltext.html

  • The functional volume product under heat flow Reviewed

    Shohei Nakamura, Hiroshi Tsuji

    Journal of the European Mathematical Society   2025.9

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    Publishing type:Research paper (scientific journal)   Publisher:European Mathematical Society - EMS - Publishing House GmbH  

    We prove that the functional volume product for even functions is increasing along the Fokker–Planck heat flow. This in particular yields a new proof of the functional Blaschke–Santaló inequality by K. Ball and Artstein-Avidan–Klartag–Milman in the even case. This result is a consequence of a new understanding of the regularizing property of the Ornstein–Uhlenbeck semigroup. That is, we establish an improvement of Borell’s reverse hypercontractivity inequality for even functions and identify the sharp range of the admissible exponents. As another consequence of successfully identifying the sharp range for the inequality, we derive a sharp L^{p} - L^{q} inequality for the Laplace transform for even functions. The best constant of the inequality is attained by centered Gaussians, which provides an analogous result to Beckner’s sharp Hausdorff–Young inequality. Our technical novelty in the proof is the use of the Brascamp–Lieb inequality for log-concave measures and Cramér–Rao’s inequality in this context.

    DOI: 10.4171/jems/1720

    arXiv

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  • Regularity of the Capacity in Operator Scaling

    Neal Bez, Anthony Gauvan, Hiroshi Tsuji

    2025.8

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    Completely positive operators are fundamental objects in quantum information
    theory and the capacity of such operators plays a pivotal role in the operator
    scaling algorithm. Using this algorithm, Garg--Gurvits--Oliveira--Wigderson
    recently established a certain quantitative continuity result for the capacity
    map at rational points. We show by different means that operator capacity
    possesses significantly greater regularity. Our argument gives local H\"{o}lder
    continuity at all points and rests on a result of
    Bennett--Bez--Buschenhenke--Cowling--Flock on weighted sums of exponential
    functions.

    arXiv

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    Other Link: http://arxiv.org/pdf/2508.02118v1

  • Duality and Heat flow Reviewed

    D. Cordero-Erausquin, N. Gozlan, S. Nakamura, H. Tsuji

    Advances in Mathematics   467   110161 - 110161   2025.5

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    Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.aim.2025.110161

    arXiv

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  • The Gaussian correlation inequality for centered convex sets

    Shohei Nakamura, Hiroshi Tsuji

    2025.4

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    We prove that the Gaussian correlation inequality holds true for centered
    convex sets. The proof is based on Milman's observation that the Gaussian
    correlation inequality may be regarded as an example of the inverse
    Brascamp--Lieb inequality. We give further extensions of the Gaussian
    correlation inequality formulated by Szarek--Werner.

    arXiv

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    Other Link: http://arxiv.org/pdf/2504.04337v1

  • Hypercontractivity beyond Nelson's time and its applications to Blaschke--Santaló inequality and inverse Santaló inequality Reviewed

    Shohei Nakamura, Hiroshi Tsuji

    to appear in Amer. J. Math.   2025

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    We explore an interplay between an analysis of diffusion flows such as
    Ornstein--Uhlenbeck flow and Fokker--Planck flow and inequalities from convex
    geometry regarding the volume product. More precisely, we introduce new types
    of hypercontractivity for the Ornstein--Uhlenbeck flow and clarify how these
    imply the Blaschke--Santal\'{o} inequality and the inverse Santal\'{o}
    inequality, also known as Mahler's conjecture. Motivated the link, we establish
    two types of new hypercontractivity in this paper. The first one is an
    improvement of Borell's reverse hypercontractivity inequality in terms of
    Nelson's time relation under the restriction that the inputs have an
    appropriate symmetry. We then prove that it implies the Blaschke--Santal\'{o}
    inequality. At the same time, it also provides an example of the inverse
    Brascamp--Lieb inequality due to Barthe--Wolff beyond their non-degenerate
    condition. The second one is Nelson's forward hypercontractivity inequality
    with exponents below 1 for the inputs which are log-convex and
    semi-log-concave. This yields new lower bounds of the volume product for convex
    bodies whose boundaries are well curved. This consequence provides a
    quantitative result of works by Stancu and Reisner--Sch\"{u}tt--Werner where
    they observed that a convex body with well curved boundary is not a local
    minimum of the volume product.

    arXiv

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    Other Link: http://arxiv.org/pdf/2212.02866v1

  • A note on ubiquity of geometric Brascamp–Lieb data Reviewed

    Neal Bez, Anthony Gauvan, Hiroshi Tsuji

    Bulletin of the London Mathematical Society   57 ( 1 )   302 - 314   2024.12

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    Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    Abstract

    Relying substantially on work of Garg, Gurvits, Oliveira and Wigderson, it is shown that geometric Brascamp–Lieb data are, in a certain sense, dense in the space of feasible Brascamp–Lieb data. This addresses a question raised by Bennett and Tao in their recent work on the adjoint Brascamp–Lieb inequality.

    DOI: 10.1112/blms.13198

    arXiv

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  • Analytic aspects of the dilation inequality for symmetric convex sets in Euclidean spaces Reviewed

    Hiroshi Tsuji

    Electronic Journal of Probability   29 ( none )   2024.1

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    Publishing type:Research paper (scientific journal)   Publisher:Institute of Mathematical Statistics  

    DOI: 10.1214/24-ejp1122

    arXiv

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  • Stability of hypercontractivity, the logarithmic Sobolev inequality, and Talagrand's cost inequality Reviewed

    Neal Bez, Shohei Nakamura, Hiroshi Tsuji

    Journal of Functional Analysis   285 ( 10 )   110121 - 110121   2023.11

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    Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jfa.2023.110121

    arXiv

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  • SYMMETRIZED TALAGRAND INEQUALITIES ON EUCLIDEAN SPACES Reviewed

    Hiroshi TSUJI

    Kyushu Journal of Mathematics   76 ( 1 )   119 - 142   2022

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    Publishing type:Research paper (scientific journal)   Publisher:Faculty of Mathematics, Kyushu University  

    DOI: 10.2206/kyushujm.76.119

    arXiv

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  • Dilation Type Inequalities for Strongly-Convex Sets in Weighted Riemannian Manifolds Reviewed

    Hiroshi Tsuji

    Analysis and Geometry in Metric Spaces   9 ( 1 )   219 - 253   2021.1

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    Publishing type:Research paper (scientific journal)   Publisher:Walter de Gruyter GmbH  

    Abstract

    In this paper, we consider a dilation type inequality on a weighted Riemannian manifold, which is classically known as Borell’s lemma in high-dimensional convex geometry. We investigate the dilation type inequality as an isoperimetric type inequality by introducing the dilation profile and estimate it by the one for the corresponding model space under lower weighted Ricci curvature bounds. We also explore functional inequalities derived from the comparison of the dilation profiles under the nonnegative weighted Ricci curvature. In particular, we show several functional inequalities related to various entropies.

    DOI: 10.1515/agms-2020-0128

    arXiv

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    Other Link: https://www.degruyter.com/document/doi/10.1515/agms-2020-0128/pdf

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Awards

  • MSJ Takebe Katahiro Prize for Encouragement of Young Researchers

    2024.9   Geometric and analytic inequalities in convex geometry

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Research Projects

  • 解析的手法による凸幾何学的問題への展開

    Grant number:24KJ0030  2024.4 - 2027.3

    日本学術振興会  科学研究費助成事業  特別研究員奨励費

    辻 寛

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    Grant amount:\3900000 ( Direct Cost: \3000000 、 Indirect Cost:\900000 )

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  • 非負の重みつきリッチ曲率をもつ空間上での幾何解析

    Grant number:22KJ2110  2023.3 - 2024.3

    日本学術振興会  科学研究費助成事業  特別研究員奨励費

    辻 寛

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    Grant amount:\1600000 ( Direct Cost: \1600000 )

    本年度の研究では、大きく分けて次の二つの問題に取り組んだ。一つはdilation不等式と同等と考えられる関数不等式の構成であり、もう一つはMahler体積と呼ばれる凸幾何学的量に対する新しい解析的な理解と定量的下界を与えたことである.
    一つ目について、dilation 不等式とは、集合を適当な意味で相似拡大した場合の体積の変化を記述する不等式であり、もともとは凸幾何学の文脈で利用されてきた。近年、この不等式は最適な形で曲がった空間(重みつきリッチ曲率の下界を伴ったリーマン多様体)上でも定式化された。本年度の研究では、dilation不等式を解析的な側面から理解することに重きを置いた。とくに、無限次元的なdilation不等式と同等であると考えられる関数不等式の構成を行った。この成果は今後論文にまとめる予定である。
    二つ目について、Mahler体積と呼ばれる幾何的量の評価に取り組んだ。Mahler体積とは、凸体とその偏極体の体積の積のことを指す。Mahler体積の最適な上界はBlaschke-Santalo不等式として知られている。一方で、最適な下界はMahler予想という名の未解決問題として知られている。本年度の研究では、Blaschke-Santalo不等式とMahler予想の両者に対する熱流による解析的な新しい理解を提示することに成功し、その応用としてMahler体積の新しい下界を与えることができた。とくに凸体の表面が十分に曲がっていれば、その凸体に対してMahler予想は正しいことを確認できた。

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  • 量子論基礎にかかる高次元バナッハ空間の幾何学的研究

    2020 - 2022

    科学技術振興機構  戦略的な研究開発の推進 戦略的創造研究推進事業 ACT-X 

    辻 寛

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    Authorship:Principal investigator 

    量子論の基礎研究の方法の一つとして“漸近的幾何解析”(AGA) を用いる方法があります。AGA とは、高次元空間内の凸体の幾何的性質を調べる分野です。特に、近年では凸体よりも広いクラスである対数凹な確率測度が重要な研究対象です。本研究では、最適輸送理論と情報理論の導入により、対数凹な確率測度の幾何的側面を発展させることを目指します。これは将来的に量子論の基礎研究に応用されることが期待されます。

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