Haoyu Hu (胡昊宇)

I am an associate professor at Nanjing University. I obtained my PhD degree from Université Paris-Sud and Nankai University in September 2014, under the supervision of Ahmed Abbes and Lei Fu. From 2015 to 2017, I was a JSPS Postdoctoral fellow at Graduate School of Mathematical Sciences, the University of Tokyo, working with Takeshi Saito. Form August 2017 to July 2018, I was a Post-doc at Max-Planck Institute for Mathematics in Bonn. In September 2018, I joint the faculty of the School of Mathematics, Nanjing University.

Here is my CV.

Email Address: huhaoyu (at) nju.edu.cn & huhaoyu1987 (at) gmail.com

Research Area

Arithmetic Algebraic Geometry, especially ramification theory of l-adic sheaves and related topics.

Publications and Preprints

Ramification and nearby cycles for l-adic sheaves on relative curves. Tohoku Math. J. (2) 67 (2015), no. 2, 153–194. (Journal, Arxiv)
Refined characteristic class and conductor formula. Math. Z. 281 (2015), no. 1-2, 571–609. (Journal, Arxiv)
(With E. Yang) Semi-continuity for total dimension divisors of étale sheaves. Internat. J. Math. 28 (2017), no. 1, 1750001. (Journal, Arxiv)
(With E. Yang) Relative singular support and the semi-continuity of characteristic cycles for étale sheaves. Selecta Math. New Ser. Vol. 24, Issue 3, (2018), 2235–2273. (Journal, Arxiv)
Logarithmic ramifications of étale sheaves by restricting to curves. IMRN, Vol. 2019, Issue 19, (2019), 5914–5952. (Journal, Arxiv)
Purely inseparable extensions and ramification filtrations. Acta Mathematica Sinica, English Series, 37, (2021), 35-58. (Journal, Arxiv)
(With J.-B. Teyssier) Characteristic cycle and wild ramification of nearby cycles of l-adic sheaves, J. reine angew. Math. vol. 2021, no. 776, (2021), 27-62. (Journal, Arxiv)
Semi-continuity of conductors, and ramification bound of nearby cycles, J. reine angew. Math., vol. 2023, no. 804, (2023), 41-103. (Journal, Arxiv)
(With J.-B. Teyssier) Cohomological boundedness for flat bundles on surfaces and applications, Compositio Math. 160(12), (2024), 2775-2827. (Journal, Arxiv)
(With J.-B. Teyssier) Semi-continuity for conductor divisors of étale sheaves, Pre-print, (2025). (Arxiv)
(With J.-B. Teyssier) Bounding ramification with coherent sheaves, To appear at Tunisian Journal of Mathematics, (2025). (Arxiv)
(With J.-B. Teyssier) Estimates for Betti numbers and relative Hermite-Minkowski theorem for perverse sheaves, Pre-print, (2025). (Arxiv)
(With J.-B. Teyssier) Characteristic cycle and wild Lefschetz theorems, Pre-print, (2025). (Arxiv) (Leitfaden)

Other Writings

Ramification et cycles proches pour les faisceaux l-adiques sur un schéma au-dessus d'un trait. Thèse de doctorat. Université Paris-Sud, Sep. 2014.

It consists first two articles of the publications.

Semi-continuity of total dimension divisors for l-adic sheaves (research announcement). RIMS Kokyuroku Besstasu B72, Algebraic Number Theory and Related Topics 2015, (2018), 85-89,

It is a research announcement of the third article of the publications. Please click on here.

Teaching

Étale cohomology (2019 spring)

Calculus I, tier 2 (2019 fall, 2020 fall, 2021 fall, 2024 fall, 2025 fall)

Calculus II and linear algebra, tier 2 (2020 spring, 2021 spring, 2022 spring)

Calculus I, tier 1 (2022 fall, 2023 fall)

Linear algebra, tier 1 (2023 spring)

Calculus II, tier 1 (2024 spring)