Guillaume Dalle
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gdalle.bsky.social
Guillaume Dalle
@gdalle.bsky.social
5.2K followers 1.9K following 600 posts
Researcher in machine learning and optimization. Open source enthusiast. Parody songwriter (aka PianoHamster). OCD survivor.
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gdalle.bsky.social
Note to self: create a second Spotify account to work on song covers. Maybe this will allow my end-of-year recap to not look like an obsessive French pop fever dream.
My top song on Spotify this year was by “Les Fatals Picards”, I listened to it 235 times
December 3, 2025 at 3:21 PM
gdalle.bsky.social
My baby #JuliaLang package got an award!
DifferentiationInterface.jl just received a national prize for open-source research software and I couldn't be prouder. We started this from a vague dream with @adrianhill.de, and reached 1000 dependents and 100k downloads last month.
Research != just papers.
A close up of the trophy for the "prix science ouverte du logiciel libre de recherche, édition 2025" (open science prize for free research software, 2025 edition)
December 2, 2025 at 9:55 AM
gdalle.bsky.social
JuliaCon Local Paris 2025 is a wrap! Thank you so much to all of our attendees and presenters, who made this conference a wonderful mix of software and science.

Next step: watch out for the talk recordings on YouTube... and see you next year in Germany!

www.youtube.com/playlist?lis...
Group photo at JuliaCon Local Paris 2025 Entrance to CNAM for JuliaCon Local Paris 2025 Keynote by Ivet Galabova at JuliaCon Local Paris 2025 Hackathon at JuliaCon Local Paris 2025
October 17, 2025 at 3:53 PM
gdalle.bsky.social
Periodic appreciation post for this gem of a review by Hannah Bast and coauthors. If you think you know how to compute shortest paths... trust me, you don't. I can give you one spoiler though: preprocessing the graph helps A LOT.
doi.org/10.1007/978-...
Screenshot of Figure 7 from "Route Planning in Transportation Networks" by Bast et al. (2016). It is a graph comparing various route-planning algorithms on the road network of Western Europe. The X axis is the preprocessing time of the graph, and the Y axis is the time taken by an individual path query after that. Both axes span several orders of magnitude along the Pareto frontier between fast queries and fast preprocessing.
October 13, 2025 at 3:40 PM
gdalle.bsky.social
JuliaCon Local Paris starts tomorrow 🤩 Which part of our amazing program are you most excited about?
#JuliaLang @juliacon.bsky.social @julialang.org
October 1, 2025 at 10:16 AM
gdalle.bsky.social
Is this the year we finally break up @neuripsconf.bsky.social?
Distracted boyfriend meme, featuring NeurIPS as the boyfriend. Angry girlfriend: “allow authors to present in Copenhagen” Girl passing by: “drop 400 accepted papers due to San Diego venue constraints”
September 19, 2025 at 8:09 AM
gdalle.bsky.social
Software enthusiasts of all fields and backgrounds, unite! Here's the exciting schedule we cooked up for #JuliaCon Local Paris 2025 (the one for #PyData is just as thrilling!).
Get your tickets while you can, and see you in a month ⌛
@julialang.org @juliacon.bsky.social @pydataparis.bsky.social
Schedule overview for JuliaCon Local Paris 2025. Full information available at https://pretalx.com/juliacon-local-paris-2025/schedule/
September 4, 2025 at 11:37 AM
gdalle.bsky.social
🚨 Breaking news 🚨
Two epic tutorials announced for #JuliaCon Local Paris 2025: one about Pluto notebooks and one about using JuMP for optimization. Be sure to get your tickets this week, otherwise the early bird pricing will be gone 🦜
@juliacon.bsky.social @julialang.org @pydataparis.bsky.social
A flashcard for a tutorial at JuliaCon Local Paris 2025. The speakers are Fons Van Der Plas (educational technology officer at TU Eindhoven) and Boshra Ariguib (master's student in CS at the University of Stuttgart). The title is "How to tell an interactive story with Pluto: lectures and dashboards". The conference takes place on October 2nd and 3rd, see the website at https://juliacon.org/local/paris2025/ A flashcard for a tutorial at JuliaCon Local Paris 2025. The speaker is Benoît Legat (assistant professor at UCLouvain). The title is "Optimization with JuMP". The conference takes place on October 2nd and 3rd, see the website at https://juliacon.org/local/paris2025/
August 22, 2025 at 3:28 PM
gdalle.bsky.social
Third keynote announced for #JuliaCon Local Paris 2025! Ivet Galabova will tell us about the #HiGHS linear programming solver, and how it combines excellence with open source.
Early bird deadline extended to Aug 31st, book your spot before they run out! And check out @pydataparis.bsky.social too!
A keynote flashcard for JuliaCon Local Paris 2025. It features Ivet Galabova (HiGHS development and integration manager at the University of Edinburgh), who will give a talk entitled "HiGHS: the story so far". The event takes place on October 2nd and 3rd in Paris, and you can book tickets at https://juliacon.org/local/paris2025/
August 18, 2025 at 3:01 PM
gdalle.bsky.social
Second keynote announcement for JuliaCon Local Paris 2025: Tim Besard will uncover the secrets of vendor-agnostic GPU programming in Julia 🤯
Don't forget to get your early bird tickets before the end of next week (see the @juliacon.bsky.social website), and to swing by @pydataparis.bsky.social too!
August 8, 2025 at 3:21 PM
gdalle.bsky.social
Want more open-source software and scientific computing in your life? Get your ticket for JuliaCon Local Paris 2025 before the end of the early bird pricing!
We have an impressive lineup of keynotes, starting with Professor Laura Grigori (EPFL) and not stopping there!
juliacon.org/local/paris2...
A presentation of our first plenary speaker at JuliaCon Local Paris 2025: Laura Grigori, Full Professor of Applied and Computational Mathematics at EPFL. She will be giving a keynote entitled "Randomization for solving high-dimensional problems: algorithms and software". The conference will take place on October 2nd and 3rd at Conservatoire national des arts et métiers, see the website https://juliacon.org/local/paris2025/ for more information!
August 6, 2025 at 5:33 PM
gdalle.bsky.social
Awesome initiative 🎉
This leaves me wondering though: how come authors attending #EurIPS still have to register for the main #NeurIPS (in the Americas) for their paper to be considered accepted?
You stopped so short of actually allowing ML researchers to fly less!
A meme where Gru explains his evil plan. 1. Organize NeurIPS event in Europe 2. Reduce carbon footprint and barriers to entry 3. Force accepted authors to present in the US
July 17, 2025 at 2:12 PM
gdalle.bsky.social
Meme of a bicycle rider enthusastic about a NeurIPS event in Europe, then self-sabotaging by forcing authors to present in the US too. At the end he’s fallen on the ground and keeps complaining that ML conferences are not eco-friendly
July 17, 2025 at 7:49 AM
gdalle.bsky.social
Sofar it doesn’t look good: neurips.cc/FAQ/AuthorRe...

“At least one author of each accepted paper must register for the main conference. A ‘Virtual Only Pass’ is not sufficient.”
A meme where Anakin and Padme discuss the logics of allowing a NeurIPS event in Europe while forcing authors to also present in the US for publication
July 17, 2025 at 7:32 AM
gdalle.bsky.social
A meme featuring Gru who wonders about NeurIPS’s plan to allow a satellite event in Europe but also force presentation in the US
July 17, 2025 at 7:29 AM
gdalle.bsky.social
There are days when math feels scary and confusing.
There are other days when it brings order and peace to a grateful universe.
July 3, 2025 at 7:33 AM
gdalle.bsky.social
Move it up down, left right oh
Switch it up like Nintendo 🎶
A screeshot from a scientific paper describing an input file format, with the following sentence highlighted: "The plan format is an ASCII string that specifies the movements of agents at each timestep, e.g., the string ”udlrw” represents a agent moving up, down, left, and right respectively, while w represents waiting at its current location." Paper reference: Shen, Bojie, Zhe Chen, Muhammad Aamir Cheema, Daniel D. Harabor, and Peter J. Stuckey. 2023. “Tracking Progress in Multi-Agent Path Finding.” arXiv. https://doi.org/10.48550/arXiv.2305.08446. Song reference: "Expresso", Sabrina Carpenter
May 22, 2025 at 11:17 AM
gdalle.bsky.social
The feeling when you have to justify to everyone why you chose to work on the Frank-Wolfe algorithm.

@matbesancon.bsky.social, tell us, how does that feel?
A screenshot from an article with the following text (FW stands for the Frank-Wolfe algorithm): "Hence, despite its wide usage in practice, the poor rate of convergence of the FW method has led methods-oriented researchers to consider FW a “dead method.” But as will be seen in the current paper, the FW method is not quite dead yet: the stiff is in fact moving! FW has further been a yardstick against which to measure new improved algorithms. Wouldn’t it be fair if FW was given the chance to shape up and fight back?"
May 19, 2025 at 6:42 AM
gdalle.bsky.social
The week of September 29th, Paris will become the epicenter of #opensource scientific computing, with a great series of events. This rare alignment creates the perfect opportunity to visit and join a vibrant community of developers, maintainers, and users!
Check this out (links in thread) ⬇️
Logos of PyData Paris, JuliaCon Local Paris and Apache Arrow Summit, all happening in September-October 2025
May 16, 2025 at 2:00 PM
gdalle.bsky.social
Sometimes I do science for the prestige.
Sometimes I do science for the money.
And sometimes I do science for the pretty pictures.

Preprint at arxiv.org/abs/2505.07308
Explanations in thread ⬇️
A scientific figure describing different sparse matrix colorings, along with the corresponding graphs. A symmetric matrix is represented by its adjacency graph, while an asymmetric matrix is represented by its bipartite graph. Star and acyclic bicolorings are two ways to color the vertices of that graph in order to compress the matrix. A screenshot from a paper showing different colorings of a matrix with a rectangular sparsity pattern. Unidirectional row and column colorings use a lot of colors, while bidirectional coloring uses only 4.
May 15, 2025 at 4:13 PM
gdalle.bsky.social
How to make #autodiff user-friendly? What lies beyond the safety of Python-world? Why does it matter for scientific machine learning?
All this, and more, in our latest preprint with @adrhill.bsky.social! Spoiler alert: it describes the most useful software I ever wrote.
arxiv.org/abs/2505.05542
A comparison of automatic differentiation paradigms between Python and Julia: - In Python, one chooses the autodiff framework first (PyTorch / JAX), then the appropriate scientific library - In Julia, one writes the scientific library first, then one tries to make it compatible with several autodiff frameworks (Enzyme, Zygote, etc)
May 12, 2025 at 6:59 PM
gdalle.bsky.social
Wanna learn about autodiff and sparsity? Check out our #ICLR2025 blog post with @adrhill.bsky.social and Alexis Montoison. It has everything you need: matrices with lots of zeros, weird compiler tricks, graph coloring techniques, and a bunch of pretty pics!
iclr-blogposts.github.io/2025/blog/sp...
A visualization of compressed column evaluation in sparse autodiff. Here, columns 1, 2 and 5 of the matrix (in yellow) have no overlap in their sparsity patterns. Thus, they can be evaluated together by multiplication with a sum of basis vectors (in purple).
April 28, 2025 at 5:07 PM
gdalle.bsky.social
I’m much better now, but I’m still not 100% okay. And like the firefighter, I wonder about my alternative life, the one without OCD in it. What kind of strange and wonderful things I could have achieved if I hadn’t gotten sick. Of if I had reacted quicker instead of letting it worsen.
Mr. Reen had long had a bedrock conviction that apart from his mental disorder, he was a good man. But today he feels mostly shame, for all the time he devoted to his compulsions instead of to his family. “I wasted a good life,” he reflected, his voice thick with disgust. “I’ve destroyed and ruined a life with this stuff.”
April 17, 2025 at 9:10 PM
gdalle.bsky.social
And even then, therapy doesn’t work for everyone. When it fails, you’re left with the shame of your irrational behaviors, which you can’t do anything about. You hide your compulsions with lame excuses so that your colleagues won’t find out. You try your best to shield your loved ones, and fail.
Mr. Reen’s children were aware of their father’s issues. The way he wouldn’t walk down certain blocks, the way he always changed his clothes outside, the way he never let them play with his uniform, unlike other firefighter fathers. And the constant sound of water running through the pipes, as he took his interminable showers. Everything depended on his decontaminating before he returned home, or his entire house would be contaminated. The drive home from the Brooklyn firehouse posed its own problem. It meant that not only was he contaminated, but his car was, too. So after each shift, when he stopped in a parking lot by the ocean to shake out his clothes, he needed to air out his car and run a lint roller over every inch of the interior. “A hideous process,” he recalled. Yet the more he cleaned, he said, the more he loathed himself. He should be with his family, not in an empty parking lot. “I know that it’s all nonsense,” he said, referring to his decontamination rituals. “And yet here I am.” He contrived half-convincing ways to hide his anxieties. Communal meals are an important part of firehouse culture, but he couldn’t bear to watch anyone handle food that he would eat. So on a spaghetti day, for example, he made sure he was the guy rolling the meatballs. “Go watch the game,” he’d tell the other guys. “Let me take care of this. It’s a guilty pleasure of mine.” Most firefighters were happy to go along. “I just thought he was meticulous to a fault,” Mr. Dunigan, the retired colleague, said. “I had no idea.”
April 17, 2025 at 9:10 PM
gdalle.bsky.social
Unfortunately, the only remedy against irrational fear is learning to accept it. That’s why OCD is so hard to heal from: exposure therapy demands that you face the thing that scares you most in the whole wide world, again and again, until it scares you a little less than before. It takes a toll.
Mr. Reen first saw a therapist at 13, and he has tried various medications and long bouts of exposure therapy, which forces patients to confront their triggers and resist their compulsions. But for some people, the success of these interventions can be limited. As part of his therapy, Mr. Reen has tried on a few occasions to go home and delay his usual decontamination rituals. But after a few hours, when he finally could tolerate it no longer, he found himself overwhelmed: He needed to do a deep clean of every room he had been in. “Because I tried to be tough, now I’ve got to spend 15 hours, not eating or drinking, just washing everything,” he recalled. Over the years, he stopped trying to resist.
April 17, 2025 at 9:10 PM