Contact details

Email address guilhem.gamard at
Office address Bureau GNI 315 Sud,
46 allée d’Italie, 69364 Lyon, France
Office time Wed-Fri, 13:00–17:00
Mobile phone +33 6 03 51 23 52

Current and past positions

I am currently (2018/2019) ATER at Ens Lyon, doing research in the MC2 group of the LIP laboratory.
I also teach at the Département d’informatique.

In 2018/2017, I was a postdoc at the Higher School of Economics, doing research in the Laboratory of Theoretical Computer Science.

Between 2014 and 2017, I prepared my PhD thesis under the supervision of Gwenaël Richomme in the ESCAPE group of the Lirmm laboratory.
I defended on 2017-06-30; here is my manuscript and here are my slides.
I also taught at the Faculté des sciences de Montpellier.

Link to my CV in French and my CV in English.


Keywords: cellular automata, combinatorics on blocks, combinatorics on words, subshifts, substitutions, tiling

I am interested in infinite words and all the phenomena you can model with them: dynamical systems, discretized curves, sampled signals, to name a few. I like to think of infinite words as streams of information with no foreseeable end, rather than infinite collections of symbols. I worked on quasiperiodicity and topological entropy, two concepts used to quantify how “symmetric” (or “predictable”) a stream is.

I am also interested in two-dimensional infinite words. Think of them as infinite grids with a given “color” (that’s our “letters”) in each cell. These objects are great to model tilings of the plane, also called tesselations. They pop up in geometry, dynamical systems, statistical physics, and are also a great playground for cellular automata. I mostly worked on quasiperiodicity (again!), and also on properties and on generalizations of the Kari-Culik tilings.

Illustration of a coverable tiling

Why not generalizing again? But going to three dimensions (and more) doesn’t bring much more than two; we’ll get richer insights by exploring completely different shapes. An hexagonal grid, for instance, might allow interesting structures in its tilings, that would be impossible in a square grid. Generally speaking, I’d like to understand which phenomena can be encoded in tilings of which “grid”, for an abstract concept of “grid”.

In particular, I’m interested in encoding computations—i.e., computers—in tilings of diversely-shaped grids. In this case, the previous question becomes: which kind of computers can be run in which kind of grids? Or, to say it in a more striking (but less accurate) way: if the shape of our universe were different, what kind of computers could we build in there?

This looks like a very nice philosophical question, but I’m also keen on getting results that practically help others. Fortunately, the road to tilings is paved with useful theorems! Indeed, tilings of grids can model many phenomena (in particular many “growth” phenomena, such as crystalization, self-assembly of DNA structures, etc.), and my results will help to quantify how hard those phenomena would be to simulate on computers, among other things.

Speaking of practical results, I also contributed to a couple of image restoration algorithms.

If you speak French, you can download my activity report (FR) and my research statement (FR).

Publications and talks

See this separate page.


See my teaching page (in French).

If you are a student interested in combinatorics on words, tilings, or subshifts, feel free to contact me—we might organize an internship in cosupervision with a permanent researcher of the lab.

Collective tasks

I volunteered for various things, listed below.


A few friends

(Don’t be offended, the list is non-exhaustive.)

Florian BarberoJulien BasteBruno BauwensJessie CarbonnelJulien DestombesFrançois DrossIlya GalanovSilvère GangloffAnaël GrandjeanMateusz Skomra

Web design credits

Design inpired by this and that.
Icons in the “contact details” section by Dannya at Open Clipart.

This page was generated with Jekyll and Kramdown, as well as jekyll-scholar for the bibliography (see Pascal Poizat’s setup). Mathematical formulae (if any) are rendered to MathML, which is then rendered by MathJax if your browser does not understand MathML.


A few quick-access links if you’re preparing a VFR flight in (mainland) France.


French language

Je ne prétends nullement écrire le français sans faute. Voici toutefois une liste de ressources très utiles, soit en cas de doute sur la langue, soit en cas de panne d’inspiration (pour trouver un synonyme par exemple).

Le bon usageCNRTLLanguagetoolVerbisteWiktionaire

Programming languages

Here’s a list of programming languages that really differ from the usual C, C++, Java, Python, etc. If you believe that “all programming languages are the same”, this might be your cure. However, try to avoid the “FORTRAN in any language” syndrome: please make an effort to really dive into your language of choice, including its environment and its culture. For instance, if you are really into Python, you should know about generators and decorators; if you are into Common Lisp, you should know how and when to write macros.


Common Lisp

Common Lisp is my favourite programming language. This doesn’t mean that CL is perfect, nor that other languages are bad. Here are a few links—some for my own usage (quick-access), some for the curious reader who might have stumbled on this page.

Software: SBCLSLIMEQuicklispQuickdocsA road to LispProjects

Books for beginners: Practical Common LispLand of LispANSI Common LispSuccessful Lisp

Books for non-beginners: On LispLet Over LambdaPAIPAMOP