Universität Regensburg   IMPRESSUM   DATENSCHUTZ
Fakultät für Mathematik Universität Regensburg
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Galois Categories and Étale Fundamental Groups
Semester
SoSe 2026

Lecturer
Moritz Kerz, Andrea Panontin, Yuenian Zhou

Type of course (Veranstaltungsart)
Seminar

German title
Galois-Kategorien und étale Fundamentalgruppen

Contents
This reading seminar is devoted to Grothendieck's formalism of Galois categories and étale
fundamental groups. Starting from the analogy between classical Galois theory, finite topological
covering spaces and finite étale covers of schemes, we will develop the abstract theory of
Galois categories and their fundamental groups, and then apply it to the construction and study of
the étale fundamental group of a scheme. The aim is to build a conceptual bridge between
algebra, topology, and algebraic geometry: after setting up the general Galois category formalism,
we will interpret the category of finite étale covers of a scheme as a Galois
category, identify its fundamental group with the étale fundamental group, and discuss its
basic properties such as homotopy exact sequences, the relation between geometric and arithmetic
fundamental groups, comparison with the topological fundamental group over complex field, and
specialization in families of schemes.

Literature
Galois Categories, Anna Cadoret

Recommended previous knowledge
1.Category theory: categories, functors, natural transformations, finite limits and colimits,
epi/mono, equivalence of categories. 2.Abstract algebra and Galois theory: finite and infinite
Galois theory, absolute Galois groups,Krull topology and profinite groups. 3.Basic algebraic
geometry: schemes, morphisms of finite type,fibre products and base change.

Time/Date
Mo, 16:00 - 18:00

Location
M 101

Additional question session
Time/Date: TBA
Location: TBA

Course homepage
https://elearning.uni-regensburg.de/course/view.php?id=73976
(Disclaimer: Dieser Link wurde automatisch erzeugt und ist evtl. extern)

Registration
  • Organisational meeting/distribution of topics: Jan 29, 2026 19:00-20:00 Online Join Zoom
    Meeting https://uni-regensburg.zoom-x.de/j/66091431893?pwd=BxbElj4MotigpLVIqR4ijhQwBobEcP.1 Meeting
    ID: 660 9143 1893 Passcode: 048159
  • Registration for course work/examination/ECTS: FlexNow
Course work (Studienleistungen)
  • Presentation: Giving a seminar talk of roughly 90 minutes
Examination (Prüfungsleistungen)
  • Detailed written report of the seminar talk
Modules
BSem, MV, MSem, BSem.2

ECTS
4,5