Blog

Fun with DALL-E 2

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You may have heard about [DALL-E 2](https://openai.com/dall-e-2/). According to its authors, it "is a new AI system that can create realistic images and art from a description in natural language." In concrete words, it is a machine learning model that has been trained to

ANR Young researcher project “Structure and Homotopy of Configuration Spaces” (SHoCoS) selected!

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Some time ago, I submitted a "Young Researcher" (JCJC) grant proposal to the French National Research Agency (ANR). I was listed as the scientific coordinator ("PI"), and I wrote the project in collaboration with [Adrien Brochier](https://abrochier.org/), [Yves Guiraud](https://webusers.imj-prg.fr/~yves.guiraud/), and [Christine Vespa](https://irma-web1.math.unistra.fr/~vespa/). [![Logo of the

“Real Homotopy of Configuration Spaces” is out

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My lecture notes *Real Homotopy of Configuration Spaces: Peccot Lecture, Collège de France, March & May 2020* has now finished production and [is available for sale](https://link.springer.com/book/10.1007/978-3-031-04428-1). The publisher sent me several complimentary copies! ![A stack of books](/post/peccot-books.webp)

LaTeX shenanigans

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Just for fun, I wrote a small $\LaTeX$ loop to define font-related single-letter commands, such as `\cA = \mathcal{A}` and so on. It is based on [this answer by David Carlisle on TeX.SE](https://tex.stackexchange.com/a/359201/14965). Here it is! ```tex %%% Dark magic \makeatletter \def\font@loop#1{% define a

Using math software for teaching calculus

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I have been teaching for seven years now. Yet somehow, I started only recently using computer algebra software (CAS) to make live illustrations of mathematical concepts in class. And I have to say that it is quite useful! ## Previous attempts As you may

Peccot Lecture notes accepted in Lecture Notes in Mathematics (CEMPI subseries)

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In 2020, the Collège de France awarded me the [Peccot Lecture and Prize](https://www.college-de-france.fr/agenda/conferencier-invite/homotopie-reelle-des-espaces-de-configuration), which "[rewards] promising mathematicians under 30 who have distinguished themselves in theoretical and applied mathematics." As part of the award, I was given the opportunity to hold a [lecture at the

Naming news for 2022

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Happy new year everyone! I hope that 2022 will be better than 2020 and 2021. As of December 19th, my university has no name. The _Conseil d'État_ (supreme court for administrative justice) has partially voided the decree of creation of "Université de Paris". They

Email hell

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For a reason I will explain below, I decided to count how many institutional email addresses I have. The answer? I have a whopping **ten** email addresses, as a result of the [administrative mille-feuille](/post/next-stop-paris) that is French academia. Here are the domains of my

The ical-ufr project

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For the past couple of months, I have been working on a side project with several colleagues from my department. In short, it's a web interface to our university's timetable system, the (infamous) ADE. For various reasons, we, the staff, are forbidden from accessing

Boardman–Vogt resolutions and bar/cobar constructions of (co)operadic (co)bimodules accepted!

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The paper ["Boardman–Vogt resolutions and bar/cobar constructions of (co)operadic (co)bimodules"](/research/bar-cobar), that Ricardo Campos, Julien Ducoulombier, and I wrote, has been accepted for publication in the journal [_Higher Structures_](https://higher-structures.math.cas.cz/)! This technical part will serve as part of the foundation on which we are going to

Dark Mode

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I just implemented a dark mode for my website! I saw that it was quite easy to do with [TailwindCSS](https://tailwindcss.com/) so I took a shot at it. To see it, enable dark mode in your browser/OS settings. If you don't want to do that

Faculty in France over the past 20 years

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*(Update 2021)* With the switch to React, this chart doesn't work anymore; I will try to make it work with React but I cannot really give any ETA. Recently the French ministry for Higher Education and Research [released some data on demographics among lecturers

arXiv2BibLaTeX: Create a BibLaTeX entry from arXiv

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tl;dr: [/a2b](/a2b) to get a `.bib` from arXiv entries. *Update May 19th, 2021: New URL.* Have you ever wanted to create a `bib` entry from an arXiv preprint? There are a few tools available, including one provided by arXiv (click on "NASA ADS" in

Select-Exams.ps1: a script to extract exams from a multi-page PDF

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With online teaching, I have to find ways to make many processes go faster, as otherwise teaching takes an inordinate amount of time compared to traditional teaching (and my salary doesn't change...). [I have already written about automating exam production](/post/exam-template) I've now taken to

Notes for my Peccot lecture, "Real Homotopy of Configuration Spaces"

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I have finished translation my notes for my [Peccot Lecture](/class/peccot) to English. They have also been expanded, with a lot more new content. For the time being, you can [find the notes here](/research/peccot). They have been submitted for publication. I would like to thank

Exam Template for Pandoc

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Like many people, I have been teaching online for some time now. In order to help students get an idea of how well they understand the material, I have been giving them and grading weekly homework (keep in mind that it is not common

The action of the orthogonal group on the sphere is not formal

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In this post, I record a simple and probably well-known fact; but since I have to remake the computation again and again (because I forget it...) I thought it would be nice to have it in an accessible place. The fact is that for

Template for letters in LaTeX

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Several people have asked me for my LaTeX template to write letters, so I guess I might as well put it up on my webpage. It uses the [`scrlttr2`](https://www.ctan.org/pkg/scrlttr2) package. I think the markup is relatively self-explanatory. The template expects a copy of your

Peccot lecture & COVID-19

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**Update**: The videos are now available on the Collège de France's website! Please [go there for the third lecture](https://www.college-de-france.fr/agenda/conferencier-invite/homotopie-reelle-des-espaces-de-configuration/homotopie-reelle-des-espaces-de-configuration-3) and [there for the fourth lecture](https://www.college-de-france.fr/agenda/conferencier-invite/homotopie-reelle-des-espaces-de-configuration/homotopie-reelle-des-espaces-de-configuration-4). As some of you may know I was one of the people chosen this year to give a [Peccot

Braid video

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Thursday I'm giving a talk at the online [Toric Topology research seminar](http://www.fields.utoronto.ca/activities/19-20/research-seminar). I was supposed to go there in person, but as you can guess, the current pandemic made that impossible. So I took the opportunity to prepare a little illustration to explain the

First Peccot lecture

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Yesterday was my first [Peccot lecture](/class/peccot)! I think it went okay. The video is going to be available soon [on this webpage](https://www.college-de-france.fr/agenda/conferencier-invite/homotopie-reelle-des-espaces-de-configuration/homotopie-reelle-des-espaces-de-configuration-1). I mainly talked about the background for my course: what are configuration spaces, why do we care about them, what do we

Animated illustration of the Fulton-MacPherson operad

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I am finishing to prepare my [Peccot Lectures](/class/peccot) that start next week. I have prepared a small animation to illustrate the Fulton--MacPherson compactification using Blender, and I think it's relatively neat! I am not a 3D artist, obviously, but (with oral explanations) I think

Peccot Lecture

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Yesterday I received a letter from the Collège de France. I have been selected to give this year a [Peccot Lecture](https://www.college-de-france.fr/prix/cours-et-prix-claude-antoine-peccot), which "rewards each year young mathematicians under 30 who have been noticed in theoretical or applied mathematics" 😃. This is of course a

Lecture Notes for the course "Homotopy Theory"

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This summer I've started to compile lecture notes for my [class](/class/19-20-homotopie) on homotopy theory in January/February. They are heavily inspired by [Grégory Ginot's lecture notes](https://www.math.univ-paris13.fr/%7Eginot/Homotopie/Ginot-homotopie2019.pdf) from last year on the same subject, although I've reorganized them a bit; in particular I swapped the last

New University of Paris

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It's official: the new University of Paris is born! For the moment, Paris Diderot University still exists, but it will merge with Paris Descartes and the new university on January 1<sup>st</sup>, 2020; the IPGP will remain a legally separate entity. (Yes, it's complicated.) We

Digging

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I dug up the tiny program I wrote to find [minimal surfaces](https://en.wikipedia.org/wiki/Minimal_surface) with fixed boundary in 2011 for the "grandes écoles" entrance exams. Ah, the memories... It's [available here](/post/digging/minimale.zip), along with some pictures. It's written in OCaml, of course! To compile it, install OCaml,

Grant: PEPS JCJC

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I applied in January to a call by the math institute (Insmi) of the CNRS, entitled *Projet Exploratoire Premier Soutien « Jeune chercheuse, jeune chercheur »* (PEPS JCJC, roughly *Exploratory Project, First Support: Young Researcher*). These are small grants (3000--6000 €) for young researchers,

Higher Structures at the CIRM

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This week I am at the _Centre international de rencontres mathématiques_ (CIRM) in Luminy. I am attending and speaking at the ["Higher Structures" conference](https://conferences.cirm-math.fr/1959.html). The whole event is wonderful! I hope I am not too out of place among the big names in the

Paper accepted in Inventiones!

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My second paper, [The Lambrechts--Stanley Model of Configuration Space](/research/ls-model), has been accepted for publication in _Inventiones Mathematicae_! This is a great honor and I am very happy. The refeereing process was a bit above average (14 months for the first report, 7 for the

Life in Paris

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I've been in Paris for almost a month now. It's been great! People at the math department and the math institute[^1] have all been welcoming and have helped me a lot in getting settled. There have been a lot of administrative procedures to complete

Why is it called “Paris 7”?

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One question people often ask is why the university is called "Paris 7", followed by the realization that there are (were!) thirteen universities in Paris, numbered from "Paris 1" to "Paris 13". Here's an attempt at explaining it (though I'm sure I can't cover

Next Stop: Paris!

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I finally got the confirmation from the ministry: I definitively got the job and I will be appointed in Paris-VII! A new life is about to begin... I've been at the Fields Institute (in Toronto) for a week now, to participate in the summer

An Eventful Week

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Last week was life-changing, to say the least. I was interviewed for two _maître de conférences_<sup>1</sup> positions, one in [Université Paris Diderot](https://www.univ-paris-diderot.fr/), the other in [Université Paris-Sud](http://www.u-psud.fr/fr/index.html). And... I got ranked first for both jobs! So by all accounts I should have a permanent

Kafka in the stars

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This is a cautionary tale, with the hope that this post could help future applicants for permanent academic positions in France. This past month, I've had the pleasure of applying for *maître de conférences* jobs -- roughly equivalent to something between assistant/associate professor. It

Defense, postdoc, new paper

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Many changes have happened in my life recently! I defended [my doctorate](/research/thesis) on November 17th. I guess I'm a doctor now! There are too many people to thank for that, so please see the "Thanks" section of my thesis. I am now entering the

New design

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Hi! You may have noticed the new URL and the new design. Now everything (my home page + my blog) is in one place, powered by [Hugo](https://gohugo.io/) and its [Academic theme](https://github.com/gcushen/hugo-academic). I was a bit fed up with Jekyll and its long building times,

A Model for Configuration Spaces of Closed Manifolds

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Last week I was at the [Max Planck Institute](https://www.mpim-bonn.mpg.de/) for the [Conference for Young researchers in homotopy theory and categorical structures](https://www.mpim-bonn.mpg.de/node/6791) (which was, by the way, a great conference -- thanks to the organizers), and I gave yet another talk about [the Lambrechts--Stanley model

First Article Accepted!

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My paper [Swiss-Cheese operad and Drinfeld center](/research/swiss-cheese) has finally been accepted! It is going to appear in the [Israel Journal of Mathematics](http://www.ma.huji.ac.il/~ijmath/). I've made the few corrections suggested by the referee (the new version is [available on the arXiv](https://arXiv.org/pdf/1507.06844)), and I'm now waiting for

Configuration Spaces Woes

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I've been neglecting this blog a lot. Juggling research, teaching, organizing a seminar, and a personal life leaves little time for writing articles! (Wait, isn't that the same complaint as last time?) Most prominently I've been spending a lot of time working on my

The Voronov Product of Operads

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My first real post in a while! It turns out that writing an actual paper (cf. previous blog post) takes a lot of time and effort. Who knew? The Voronov product of operads is an operation introduced by Voronov in his paper _The Swiss-cheese

Paper: The Lambrechts–Stanley Model of Configuration Spaces

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I have uploaded a new preprint, [_The Lambrechts--Stanley Model of Configuration Spaces_](/research/ls-model), which you can find on [arXiv](https://arXiv.org/abs/1608.08054). Here is the abstract: > We prove the validity over ℝ of a CDGA model of configuration spaces for simply connected manifolds with vanishing Euler characteristic,

Young Topologists Meeting 2016

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This week I was at the [Young Topologists Meeting](https://www.math.ku.dk/english/research/conferences/2016/ytm2016/)! It's gotten even bigger than two years ago, as there were more than 180 participants this year. The conference was quite interesting, and Copenhagen is a really nice city! The main theme was homological stability,

Talk at ETH Zürich

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Last week I was invited by [Thomas Willwacher](http://user.math.uzh.ch/willwacher/) to ETH Zürich for a few days, during which I also had the opportunity to give a talk at the "Talks in Mathematical Physics" seminar. It was a very interesting few days, and I'm very grateful

Oberwolfach

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I just came back from the [Mathematisches Forschungsinstitut Oberwolfach](https://www.mfo.de/)! ![The library](/post/mfo/mfo.webp) I was there for the "[Factorization Algebras and Functorial Field Theories](https://www.mfo.de/occasion/1619/www_view)" workshop. It was an incredible experience. The talks were all, of course, very interesting, and I learned a lot about QFT. But

Infinity-Operads Demystified

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The purpose of this post is to record the definition of ∞-operads and explain why it works like that. For this I'm using Lurie's definition of ∞-operads; there is also a definition by Cisinski--Moerdijk--Weiss using dendroidal sets, about which I might talk later. Indeed,

Talk in Paris!

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Today I'm in Paris! I'm giving a talk at the [Séminaire de Topologie](https://www.imj-prg.fr/spip.php?article67) of the Institut de Mathématiques de Jussieu--Paris Rive Gauche, about my preprint [Swiss-Cheese operad and Drinfeld center](/research/swiss-cheese). Here is the abstract of the talk (in French): > Il est possible de

The Milnor–Moore Theorem

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This post is about the Milnor--Moore theorem, a powerful tool describing the structure of (co)commutative Hopf algebras. Like the [Eckmann--Hilton argument](/post/eckmann-hilton), it shows that having multiple compatible operations on the same object can lead to unexpected results about the object. Briefly, the theorem says

Paper Accepted!

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My first article has been accepted for publication with minor revisions! Entitled "Opérades et structures commutatives à homotopie près" (yes, it's in French), it will appear in the *Graduate Student Mathematical Diary*, edited by the [Mediterranean Institute For The Mathematical Sciences](http://www.mims.tn/). The article is

Acyclic Models

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The theorem(s) of acyclic models are a rather powerful technique for proving that some functors defined on truncated chain complexes can be extended in higher dimensions, and that two such functors are homotopic, by proving it on a small class of "model" objects. For

About Abelian Bimodules

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This post is about something somewhat weird I noticed about infinitesimal bimodules over operads and their relationships with some $E_n$ operads. I don't know if it's something significant, and I'd definitely be interested to hear more about it. ## Context: abelian bimodules As I

The Eckmann–Hilton Argument

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As promised, this post is about the famous [Eckmann--Hilton argument](https://en.wikipedia.org/wiki/Eckmann%E2%80%93Hilton_argument). This argument, on the surface, looks like a simple algebraic trick; but it has deep consequences, which I will now try to explain. This post is an expanded version of a [math.SE answer](https://math.stackexchange.com/a/1203969/10014) I