Algebra Days in Caen 2024: Algebraic aspects of configuration spaces and moduli spaces

March 18–20 2024

This issue of the series Algebra Days in Caen is devoted to configuration spaces and moduli spaces, which will be considered from various algebraic and topological perspectives. A particular focus will be made on dialogue between different communities working on the subject.

You will find the conference poster here.


  • Cristina Anghel (Leeds)
  • Andrea Bianchi (Bonn)
  • Rachael Boyd (Glasgow)
  • Tara Brendle (Glasgow)
  • John Guaschi (Caen)
  • Najib Idrissi (Paris)
  • Erik Lindell (Paris)

Practical information

To register, please follow this link before February 20.

If you have any questions, please contact the organisers, Arthur Soulié and Victoria Lebed.

We can provide financial support to junior participants. Please contact the organisers if you are interested.

Some hotels in Caen: Hôtel du Château, Hôtel des Quatrans, Hôtel la Fontaine.

Conference venue: Université de Caen Normandie, Campus 2, building Sciences 3, Lecture Hall S3 057 on Monday and Tuesday, and Amphi 500 on Wednesday. To get there, you may follow these instructions.

The list of participants is available here.

The conference dinner will take place on Tuesday, March 19 at the restaurant L'Aromate, 9 Rue Gemare, Caen.

Polaris, a sculpture in Caen. Image credit: Quentin Riel.


Monday, March 18
Location: S3-057

14:00-14:30 Welcome and registration
14:30-15:30 Najib Idrissi (mini-course)
15:30-16:00 Coffee break
16:00-17:00 A talk

Tuesday, March 19
Location: S3-057

9:30-10:30 Najib Idrissi (mini-course)
10:30-11:00 Coffee break
11:00-12:00 A talk
12:00-14:00 Lunch
14:00-15:00 A talk
15:00-15:30 Coffee break
15:30-16:30 A talk
16:45-17:45 A talk

Wednesday, March 20
Location: amphi 500

09:00-10:00 Najib Idrissi (mini-course)
10:00-11:00 A talk
11:00-11:30 Coffee break

Titles and abstracts

Cristina Anghel:

Andrea Bianchi: String topology and graph cobordisms

Rachael Boyd: Diffeomorphisms of reducible 3-manifolds

I will talk about joint work with Corey Bregman and Jan Steinebrunner, in which we study the moduli space BDiff(M), for M a compact, connected, reducible 3-manifold. We prove that when M has non-empty boundary, BDiff(M rel ∂M) has the homotopy type of a finite CW-complex. This was conjectured by Kontsevich and previously proved in the case where M is irreducible by Hatcher and McCullough.

Tara Brendle:

John Guaschi: Finite subgroups of surface braid groups

Najib Idrissi: Operadic structures of configuration spaces (mini-course)

Erik Lindell: The Torelli group and tautological cohomology classes with twisted coefficients

In the late 90's, Faber made a series of conjectures about the tautological subring of the Chow ring of Mg, the moduli space of algebraic curves, and certain variants of this moduli space. One of the conjectures states that the tautological ring should be a Gorenstein ring (i.e. satisfy Poincaré duality). This conjecture is no longer generally believed to hold and counterexamples have been found for some variants of Mg. In a previous (failed) project of mine I attempted to disprove the conjecture for a certain variant Mg, through an approach using homology of the Torelli group, an interesting subgroup of the mapping class group of a surface. In this talk, I will discuss the background of the problem in more detail, explain the intended approach and why it failed and if time permits, talk about the results this project led to instead.

Financial support:

Laboratoire de Mathématiques Nicolas Oresme, Université de Caen Normandie, CNRS