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Séverin Philip

Postdoctoral Researcher

Arithmetic Geometry and Number Theory

Stockholm University
Department of Mathematics
Albanovägen 28

SE-106 91 Stockholm, Sweden

Albano house 1, office : B1370



Research interests

My work deals mainly with monodromy Galois actions on geometric objects and their arithmetic invariants. In particular I am interested in the geometry of abelian varieties and their arithmetic reduction properties as semi-stability and the Faltings height and also in the moduli spaces of curves and their étale-homotopic Galois theory.

Articles and thesis
  • 7 - The local obstruction to semi-stable reduction for abelian varieties. 2025 (14p). [pdf,arxiv]  

  • 6 - The (p,t,a)-inertial groups as finite monodromy groups. 2025 (29p). [pdf,arxiv]  

  • 5 - Groupes de monodromie finie des variétés abéliennes. 2024 (33p). [pdf, arxiv]  

  • 4 - On Oda's problem and special loci. Joint work with B. Collas. Journal de l’Institut de Mathématiques de Jussieu. 2024. 37p. (available online at Journal de l’Institut de Mathématiques de Jussieu) [pdf, arxiv]  

  • 3 - On the semi-stability degree for abelian varieties. Bulletin of the London Mathematical Society. 2022. (available online at Bulletin of the London Mathematical Society) [pdf, arxiv]  

  • 2 - Variétés abéliennes CM et grosse monodromie finie sauvage. Journal of Number Theory. 240. 2022. p. 163-195 [pdf, arxiv]  

  • 1 - Fields of definition of abelian subvarieties. Journal de Théorie des Nombres de Bordeaux. 2022. (available online at Journal de Théorie des Nombres de Bordeaux) [pdf, arxiv]  

  • 0 - Thèse de doctorat  : Réduction semi-stable des variétés abéliennes, Université Grenoble Alpes, Institut Fourier. 2021 [pdf]
Curriculum vitae
Invited Talks at seminars and conferences since 2023
  • 2025 Nov. Arithmetic seminar, Université de Lille, L'obstruction a la réduction semi-stable pour les variétés abéliennes
  • 2025 Nov. Algebra and geometry seminar, Stockholm, The obstruction to semi-stable reduction for abelian varieties
  • 2025 Jun. Copenhagen seminar, Copenhagen, Semi-stable reduction of abelian varieties and (p,t,a)-inertial groups
  • 2025 Jun. Arithemetic and algebraic geometry seminar, Strasbourg, Problème de Oda, l-monodromie et lieux spéciaux
  • 2025 Apr. Spring seminar on Arithmetic Galois theory in Toyonaka , Osaka, On Oda's problem and special loci
  • 2025 Feb. Number theory seminar, Bordeaux, France, Groupes de monodromie finie et degré de semi-stabilité pour les variétés abéliennes
  • 2024 Nov. Number theory seminar, Besançon, Une caractérisation de la monodromie finie des variétés abéliennes
  • 2024 Sep. Rencontre de théorie des nombres EThéN, CIRM, Luminy, Le degré de semi-stabilité pour les variétés abéliennes.
  • 2024 Jul. Sendai-Hiroshima number theory conference, Sendai, The semi-stability degree for abelian varieties.
  • 2024 Jun. RIMS AG/NT seminar, RIMS, Kyoto universty, Finite monodromy groups of abelian varieties.
  • 2024 Jun. Hokkaido Algebra seminar, Sapporo universty, Semi-stable reduction and finite monodromy groups of abelian varieties.
  • 2024 Apr. Niigata Algebra seminar, Niigata universty, Oda's problem for cyclic special loci.
  • 2024 Mar. Anabelian Geometry in Tokyo, Tokyo Institute of Technology, Oda's problem for cyclic special loci.
  • 2024 Mar. The 20th Mathematics Conference for Young Researchers, Hokkaido University (online), The classical problem of Oda and an analogue for cyclic special loc.
  • 2024 Mar. Low dimensional topology and number theory XV, Kyushu University, The maximal degeneration method for special loci.
  • 2024 Jan. Aichi Number Theory seminar, Nagoya University, On Oda's problem and special loci.
  • 2023 Dec. Copenhagen Number Theory seminar, University of Copenhagen (online), A new construction for finite monodromy groups.
  • 2023 Sept. MFO-RIMS Tandem workshop 2023 - Arithmetic Homotopy and Galois Theory, RIMS, Oda's problem for cyclic special loci.
  • 2023 May Séminaire variétés rationelles, Ecole Polytechnique, Palaiseau, France, Degré de semi-stabilité des variétés abéliennes et monodromie finie.
  • 2023 May Number theory seminar, Bordeaux university, Bordeaux, France, Groupes de monodromie finie et variétés abéliennes CM.
  • 2023 Mar. Arithmetic and Homotopic Galois Theory, Hybrid, Paris-Kyoto
  • 2023 Jan. Arithmetic seminar, Université de Lille, Groupes de monodromie finie et variétés abéliennes CM
    • Atelier de Géométrie Arithmétique

    I am the main organizer of a Franco-Japanese workshop for young researchers named ''Atelier de Géométrie Arithmétique''. You can find below the webpages, programs and notes from the workshop below.

  • Spaces and perfectoids. [webpage, program, poster, notes]  

  • Around the Grothendieck-Teichmuller group. [webpage, program, poster, notes]  

  • Local-global principles and the patching method. [webpage, program, poster, notes]  

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